The Phenotypic Variability Associated with Hepatocyte Nuclear Factor 1B Genetic Defects Poses Challenges in Both Diagnosis and Therapy

The evolving landscape of clinical genetics is becoming increasingly relevant in the field of nephrology. HNF1B-associated renal disease presents with a diverse array of renal and extrarenal manifestations, prominently featuring cystic kidney disease and diabetes mellitus. For the genetic analyses, whole exome sequencing (WES) and multiplex ligation-dependent probe amplification (MLPA) were performed. Bioinformatics analysis was performed with Ingenuity Clinical Insights software (Qiagen). The patient's electronic record was utilized after receiving informed consent. In this report, we present seven cases of HNF1B-associated kidney disease, each featuring distinct genetic abnormalities and displaying diverse extrarenal manifestations. Over 12 years, the mean decline in eGFR averaged -2.22 ± 0.7 mL/min/1.73 m2. Diabetes mellitus was present in five patients, kidney dysplastic lesions in six patients, pancreatic dysplasia, hypomagnesemia and abnormal liver function tests in three patients each. This case series emphasizes the phenotypic variability and the fast decline in kidney function associated with HNF-1B-related disease. Additionally, it underscores that complex clinical presentations may have a retrospectively straightforward explanation through the use of diverse genetic analytical tools.

HNF1A gene mutations and premature ovarian failure (POF): evidence from a clinical paradigm combining MODY 3 and POF

Premature ovarian failure (POF) defines the occurrence of ovarian failure prior to the age of 40. It occurs in one out of 100 women but is very rare before age 20 (1:10,000). Maturity-onset diabetes of the young (MODY), caused by mutations in the HNF1A gene, is also a rare disorder; all types of MODY account for 1-2% of adult diabetic cases. These two rare nosologic entities coexisted in an adolescent girl evaluated for delayed puberty. Although this combination could represent a chance association, an interrelation might exist. We examined HNF1A expression in human fetal and adult ovaries by immunohistochemistry using a polyclonal HNF1A antibody. HNF1A protein was expressed in both the fetal and adult human ovaries. Based on these findings, we hypothesize that HNF1A participates in ovarian organogenesis and/or function and that mutations in the HNF1A gene might represent another molecular defect causing POF, possibly in combination with other genetic factors. The study underlines the importance of rare clinical paradigms in leading the way to elucidation of the pathogenetic mechanisms of rare diseases.

A mild and transient form of autosomal recessive Pseudohypoaldosteronism type 1 (PHA1) caused by a novel mutation in the SCNN1A gene

OBJECTIVE

To investigate the genetic etiology in a cohort of patients with a clinical, biochemical, and hormonal profile suggestive of a mild and transient form of PHA1. Patients - Methods: Twelve PHA1 patients with clinical and biochemical data were analyzed. The coding regions of NR3C2 and SCNN1A genes were sequenced. Human αENaC wt, αF226C and αF226S ENaC variants, were expressed in Xenopus laevis oocytes. to evaluate ENaC activity. The protein expression of α ENaC wt and mutants was determined by Western blot.

RESULTS

All patients were homozygotes for the p.Phe226Cys of the a subunit of ENaC, resulting in significantly reduced ENaC activity (83% reduction). Quantitative western blot analysis was consistent with a reduced ENaC protein expression for the αF226C compared to wt.

CONCLUSIONS

We present 12 patients from 4 different families with a mild and transient autosomal recessive PHA1 due to a novel homozygous missense mutation in the SCNN1A gene. Functional studies showed that the p.Phe226Cys substitution mutation in ENaC leads to a partial loss of function resulting mainly from both a decrease in the intrinsic ENaC activity, and a reduction in channel expression at the protein level. The partial loss of ENaC function could explain the mild phenotype, variable expressivity, and the transient course of the disorder in these patients.

Addison's disease without hyperpigmentation in pediatrics: pointing towards specific causes

INTRODUCTION

Hyperpigmentation of skin and mucous membranes comprises a hallmark of the clinical diagnosis of Addison's disease. However, there have been reports of patients with adrenal insufficiency from diverse causes who did not develop hyperpigmentation. The pathophysiology responsible for the absence of increased pigmentation is not clearly defined in many cases.

CASE PRESENTATION

We present a patient with isolated glucocorticoid deficiency due to two novel heterozygous variants in the sphingosine-1-phosphate lyase 1 (SPGL1) gene that did not develop any hyperpigmentation.

DISCUSSION

We elaborate on the presumed mechanism of the absence of hyperpigmentation in adrenal insufficiency due to SPGL1 deficiency and discuss the other reported cases of Addison's disease without hyperpigmentation and the possible mechanism accounted for.

CONCLUSION

Absence of hyperpigmentation, a basic component of the clinical diagnosis of Addison's disease, may lead to delay of a critical diagnosis, while causes that result in adrenal insufficiency without hyperpigmentation should explicitly be considered in pediatric cases where adrenal failure is documented by clinical symptomatology and biochemistry.

Genetic screening of hypertensive patients with aldosterone hypersecretion under conditions of stress

PURPOSE

Although ACTH is considered a secondary regulator of aldosterone production, patients with apparent essential hypertension have been treated with mineralocorticoid receptor antagonists (MRAs). In this study, we aimed to identify potentially damaging variants that might be implicated in the phenotype of a well-characterized cohort of 21 hypertensive patients without PA but with stress-induced aldosterone hypersecretion. The patients' blood pressure was normalized though MRA administration.

METHODS

Genetic screening was performed through whole-exome sequencing (WES), and variants in PA-associated or in ion-channels of aldosterone-regulating genes were prioritized. Variants with population frequency < 0.01, predicted to alter protein structure and classified as likely pathogenic by in silico tools, were retained.

RESULTS

Qualifying variants were identified in nine of the 21 patients screened. Seven patients were carriers of six potentially damaging variants in six genes associated with PA (KCNK9, KCNK5, ATP13A3, SLC26A2, CACNA1H, and CACNA1D). A novel variant in the KCNK9 gene (p.V221M) is reported. Our analysis revealed two variants in two novel susceptibility genes for aldosterone hypersecretion, namely, KCNK16 (p.P255H) and CACNA2D3 (p.V557I).

CONCLUSION

WES revealed potentially damaging germline variants in genes participating in aldosterone synthesis/regulating pathways in 9/21 patients of our cohort. The variants identified might play a role in aldosterone hypersecretion under conditions of stress. The potential pathogenicity of these variants should be examined in future functional studies.

A human paradigm of LHX4 and NR5A1 developmental gene interaction in the pituitary gland and ovary?

The pituitary gland, as a nodal component of the endocrine system, is responsible for the regulation of growth, reproduction, metabolism, and homeostasis. Although pituitary formation though the hierarchical action of different transcription factors is well studied in mouse models, there is little evidence of the analogous developmental processes in humans. Herein, we present a female patient with a phenotype that includes blepharoptosis-ptosis-epicanthus syndrome and premature ovarian failure. Clinical exome sequencing revealed two heterozygous variants in two genes, LHX4 (pathogenic) and NR5A1 (VUS) genes and no mutation in FOXL2 gene. We propose a model of genetic interaction between LHX4 and NR5A1 during pituitary and ovarian development that may lead to a similar phenotype mediated by reduced FOXL2 expression.

Whole Exome Sequencing Points towards a Multi-Gene Synergistic Action in the Pathogenesis of Congenital Combined Pituitary Hormone Deficiency

Combined pituitary hormone deficiency (CPHD) is characterized by deficiency of growth hormone and at least one other pituitary hormone. Pathogenic variants in more than 30 genes expressed during the development of the head, hypothalamus, and/or pituitary have been identified so far to cause genetic forms of CPHD. However, the etiology of around 85% of the cases remains unknown. The aim of this study was to unveil the genetic etiology of CPHD due to congenital hypopituitarism employing whole exome sequencing (WES) in two newborn patients, initially tested and found to be negative for PROP1, LHX3, LHX4 and HESX1 pathogenic variants by Sanger sequencing and for copy number variations by MLPA. In this study, the application of WES in these CPHD newborns revealed the presence of three different heterozygous gene variants in each patient. Specifically in patient 1, the variants BMP4; p.Ala42Pro, GNRH1; p.Arg73Ter and SRA1; p.Gln32Glu, and in patient 2, the SOX9; p.Val95Ile, HS6ST1; p.Arg306Gln, and IL17RD; p.Pro566Ser were identified as candidate gene variants. These findings further support the hypothesis that CPHD constitutes an oligogenic rather than a monogenic disease and that there is a genetic overlap between CPHD and congenital hypogonadotropic hypogonadism.

Congenital adrenal hyperplasia caused by compound heterozygosity of two novel CYP11B1 gene variants

BACKGROUND

Congenital adrenal hyperplasia (CAH) is an autosomal recessive disorder caused by pathogenic variants in seven genes involved in the cortisol and aldosterone biosynthetic pathway. The second most common cause, 11β-hydroxylase deficiency (11βOHD), is attributed to pathogenic variants in the CYP11B1 gene encoding for the enzyme 11β-hydroxylase (11βOH).

CASE PRESENTATION

A 13-year-old girl was referred to the pediatric endocrinologist due to a syncopal episode. She is the third child of non-consanguineous parents. She presented with premature adrenarche at the age of 6 years and menarche at the age of 12 years. On physical examination, her height was 154.5 cm and weight 50 kg, while she presented with acne, hirsutism, clitoromegaly, and normal blood pressure. Laboratory investigation revealed increased androgen levels and poor cortisol response to the ACTH stimulation test. From the family history, the mother was diagnosed with CAH at the age of 10 years and was under treatment with methylprednisolone. Previous molecular investigation of the CYP21A2 gene was negative. Due to the increased androstenedione levels in the index patient, the suspicion of 11βOH was raised, and she was investigated for 11-deoxycortisol, 11-deoxycorticosterone, and CYP11B1 gene pathogenic variants. The patient and her mother were found to be compound heterozygous for two novel variants of the CYP11B1 gene.

CONCLUSION

We present a case of CAH due to compound heterozygosity of two novel pathogenic variants of the CYP11B1 gene, emphasizing the importance of molecular investigation in order to confirm clinical diagnosis and allow proper genetic counseling of the family.

lncRNA NORAD is consistently detected in breastmilk exosomes and its expression is downregulated in mothers of preterm infants

Breast milk is the ideal food for infants and undoubtedly has immediate and long-term benefits. Breast milk contains extracellular vesicles (EVs) i.e., exosomes secreted by maternal breast cells. Exosomes carry genetic material, such as long non-coding RNAs (lncRNAs), which possibly participate in cell-to-cell communications, as they are known to regulate critical gene pathways. The aim of the present study was to screen human breastmilk exosomes for their lncRNA cargo and to examine exosomal lncRNA levels associated with milk obtained from mothers that gave birth at term or prematurely (<37 weeks of gestation). Samples were collected at 3 weeks postpartum from 20 healthy, breastfeeding mothers; 10 mothers had given birth at full-term and 10 mothers preterm. Exosomal RNA was extracted from all samples and the expression of 88 distinct lncRNAs was determined using reverse transcription-quantitative PCR. A total of 13 lncRNAs were detected in ≥85% of the samples, while 31 were detected in ≥50% of the samples. Differential expression analysis of the lncRNAs between the two groups revealed ≥2-fold differences, with generally higher lncRNA concentrations found in the milk of the mothers that gave birth at term compared with those that gave birth preterm. Among these, the non-coding RNA activated at DNA damage (NORAD) was prominently detected in both groups, and its expression was significantly downregulated in the breast milk exosomes of mothers who delivered preterm. On the whole, the present study demonstrates that breast milk lncRNAs may be important factors of normal early human development. Collectively, the presence of lncRNAs in human breast milk may explain the consistent inability of researchers to fully 'humanize' animal milk.

A case of digenic maturity onset diabetes of the young with heterozygous variants in both HNF1Α and HNF1Β genes

BACKGROUND

Maturity onset diabetes of the young (MODY) is the most commonly reported form of monogenic diabetes in the pediatric population. Only a few cases of digenic MODY have been reported up to now.

CASE REPORT

A female patient was diagnosed with diabetes at the age of 7 years and was treated with insulin. A strong family history of diabetes was present in the maternal side of the family. The patient also presented hypomagnesemia, glomerulocystic kidney disease and a bicornuate uterus. Genetic testing of the patient revealed that she was a double heterozygous carrier of HNF1A gene variant c.685C > T; (p.Arg229Ter) and a whole gene deletion of the HNF1B gene. Her mother was a carrier of the same HNF1A variant.

CONCLUSION

Digenic inheritance of MODY pathogenic variants is probably more common than currently reported in literature. The use of Next Generation Sequencing panels in testing strategies for MODY could unmask such cases that would otherwise remain undiagnosed.

Glucocorticoid Signaling and Epigenetic Alterations in Stress-Related Disorders

Stress is defined as a state of threatened or perceived as threatened homeostasis. The well-tuned coordination of the stress response system is necessary for an organism to respond to external or internal stressors and re-establish homeostasis. Glucocorticoid hormones are the main effectors of stress response and aberrant glucocorticoid signaling has been associated with an increased risk for psychiatric and mood disorders, including schizophrenia, post-traumatic stress disorder and depression. Emerging evidence suggests that life-stress experiences can alter the epigenetic landscape and impact the function of genes involved in the regulation of stress response. More importantly, epigenetic changes induced by stressors persist over time, leading to increased susceptibility for a number of stress-related disorders. In this review, we discuss the role of glucocorticoids in the regulation of stress response, the mechanism through which stressful experiences can become biologically embedded through epigenetic alterations, and we underline potential associations between epigenetic changes and the development of stress-related disorders.

Unravelling the Genetic Basis of ACTH-Mediated Aldosterone Hypersecretion in Hypertensive Patients Without Primary Aldosteronism

Introduction: Primary aldosteronism (PA), a condition characterized by autonomous aldosterone hypersecretion, constitutes the most common cause of secondary hypertension. PA includes both sporadic and familial forms, inherited in an autosomal dominant manner. Recent evidence suggests a higher prevalence of aldosterone excess among hypertensive patients than previously thought, while chronic stress-related ACTH-mediated aldosterone hypersecretion has also been implicated in the pathogenesis of essential hypertension. Objective: To determine whether genetic variations of aldosterone regulating genes could be implicated in the ACTH-mediated aldosterone hypersecretion in hypertensive patients without PA. Methods: Twenty-one hypertensive patients without PA, who exhibited ACTH-mediated aldosterone hypersecretion, underwent Whole Exome Sequencing (WES) on Novaseq 6000 platform (Illumina). As hyper-responders were defined patients whose aldosterone (ALD) and aldosterone-to-renin ratio (ARR) response to ultra-low ACTH stimulation test was above the 97.5th percentile values of controls. The cutoff levels for ALD and ARR were 1300 pmol/L and 77 pmol/mIU, respectively. Variant calling was performed according to GATK best practices and VCF files were filtered for variants in 25 genes associated with PA. To identify new susceptibility genes for PA, VCF files were also intersected for variants in ion channels encoding genes involved in pathways responsible for PA. The analysis was restricted to rare variants with gnomAD frequency &lt; 1%. Qualifying variants and pathogenicity were established by employing in silico tools. Copy Number Variant analysis was performed using ExomeDepth algorithm. Results: Eight out of twenty-one patients were heterozygous for rare variants in genes associated with PA, while two patients carried potentially damaging variants in genes encoding ion channels. Specifically, one patient was heterozygous for p.V259M in KCNK5 and one patient was heterozygous for the novel variant p.V221M in KCNK9. Two additional patients carried a predicted pathogenic variant p.R492W in SLC26A2, a gene that has been associated with PA through GWAS. Germline variants in calcium channel genes were also detected in three patients: p.V249I in CACNA1H, p.R462Q in CACNA1D and p.L1801M in CACNA1I, while one patient carried an ultra-rare variant (p.R26L) in ATP13A3. Finally, in two patients we identified rare, likely pathogenic variants in two new susceptibility genes for PA: KCNK16 (p.P255H) and CACNA2D3 (p.V55I). Conclusion: These findings support the notion that mutations in aldosterone synthesis/secretion regulating genes may sensitize zone glomerulosa cells to ACTH stimulation, leading to aldosterone hypersecretion under conditions of stress. We also report two novel candidate susceptibility genes for PA, KCNK16 and CACNA2D3, and one novel variant in KCNK9.

Detection of hepatocyte nuclear factor 4A(HNF4A) gene variant as the cause for congenital hyperinsulinism leads to revision of the diagnosis of the mother

OBJECTIVES

Congenital Hyperinsulinism (CHI) is the most common cause of persistent hypoketotic hypoglycaemia in neonates and infants. It is a genetic disorder with both familial and sporadic forms.

CASE PRESENTATION

In this study, we examined two unrelated infants of diabetic mothers (IDMs) presented with HH. DNA sequencing (Sanger and NGS panel) identified pathogenic variants of the Hepatocyte Nuclear Factor 4A (HNF4A) gene in both families. Pathogenic variants of HNF4A gene are reported to cause HH in the newborn period and Maturity Onset Diabetes of the Young (MODY) later in life. The diagnosis of MODY was made in retrospect for the two mothers, thus improving the management of their diabetes.

CONCLUSION

Genetic testing for CHI is strongly recommended if neonatal hypoglycemia persists. A family history of MODY or presumed type II diabetes can support that the affected gene is HNF4A.

Molecular Analysis of the CYP11B2 Gene in 62 Patients with Hypoaldosteronism Due to Aldosterone Synthase Deficiency

CONTEXT

Isolated congenital hypoaldosteronism presents in early infancy with symptoms including vomiting, severe dehydration, salt wasting, and failure to thrive. The main causes of this rare autosomal recessive disorder is pathogenic variants of the CYP11B2 gene leading to aldosterone synthase deficiency.

OBJECTIVE

To investigate the presence of CYP11B2 pathogenic variants in a cohort of patients with a clinical, biochemical, and hormonal profile suggestive of aldosterone synthase deficiency.

DESIGN

Clinical and molecular study.

SETTING

Tertiary academic Children's Hospital, Center for Rare Pediatric Endocrine Diseases.

PATIENTS AND METHODS

Sixty-two patients (56 unrelated patients and 6 siblings), with hypoaldosteronism and their parents, underwent CYP11B2 gene sequencing after its selective amplification against the highly homologous CYP11B1 gene. In silico analysis of the identified novel variants was carried out to evaluate protein stability and potential pathogenicity.

RESULTS

CYP11B2 gene sequencing revealed that 62 patients carried a total of 12 different pathogenic CYP11B2 gene variants, 6 of which are novel. Importantly, 96% of the 56 patients carried the previously reported p.T185I variant either in homozygosity or in compound heterozygosity with another variant. The 6 novel variants detected were: p.M1I, p.V129M, p.R141Q, p.A165T, p.R448C, and the donor splice site variant of intron 8, c.1398 + 1G > A.

CONCLUSION

Molecular diagnosis was achieved in 62 patients with aldosterone synthase deficiency, the largest cohort thus far reported. Six novel genetic variants were identified as possibly pathogenic, extending the spectrum of reported molecular defects of the CYP11B2 gene.

Emerging technologies in pediatrics: the paradigm of neonatal diabetes mellitus

In the era of precision medicine, the tremendous progress in next-generation sequencing technologies has allowed the identification of an ever-increasing number of genes associated with known Mendelian disorders. Neonatal diabetes mellitus is a rare, genetically heterogeneous endocrine disorder diagnosed before 6 months of age. It may occur alone or in the context of genetic syndromes. Neonatal diabetes mellitus has been linked with genetic defects in at least 26 genes to date. Novel mutations in these disease-causing genes are being reported, giving us a better knowledge of the molecular events that occur upon insulin biosynthesis and secretion from the pancreatic β-cell. Of great importance, some of the identified genes encode proteins that can be therapeutically targeted by drugs per os, leading to transitioning from insulin to sulfonylureas. In this review, we provide an overview of pancreatic β-cell physiology, present the clinical manifestations and the genetic causes of the different forms of neonatal diabetes, and discuss the application of next-generation sequencing methods in the diagnosis and therapeutic management of neonatal diabetes and on research in this area.

Next generation sequencing targeted gene panel in Greek MODY patients increases diagnostic accuracy

BACKGROUND

Maturity Onset Diabetes of the Young (MODY) constitutes a genetically and clinically heterogeneous type of monogenic diabetes. It is characterized by early onset, autosomal dominant inheritance and a defect in pancreatic β-cell insulin secretion. To date, various MODY subtypes have been reported, each one of a distinct genetic etiology.

OBJECTIVE

The aim of this study was to identify the molecular defects of 50 patients with MODY employing the methodology of next generation sequencing (NGS) targeted gene panel.

METHODS

A panel of seven MODY genes was designed and employed to screen 50 patients fulfilling the MODY diagnostic criteria. Patients with no pathogenic, likely pathogenic or uncertain significance variants detected, were further tested by multiplex ligation-dependent probe amplification (MLPA) for copy number variations (CNVs).

RESULTS

Eight different pathogenic or likely pathogenic variants were identified in eight MODY patients (diagnostic rate 16%). Five variants of uncertain significance were also detected in seven MODY patients. Five novel pathogenic and likely pathogenic variants were detected in the genes GCK; p.Cys371X, HNF1A; p.Asn402Tyr, HNF4A; p.Glu285Lys, and ABCC8; p.Met1514Thr and p.Ser1386Phe. Two de novo heterozygous deletions of the entire HNF1B gene were detected in two patients, raising the diagnostic rate to 20%.

CONCLUSIONS

Although many MODY patients still remain without exact MODY type identification, the application of NGS methodology provided rapid results, increased diagnostic accuracy, and was cost-effective compared to Sanger sequencing. Accurate genetic diagnosis of the MODY subtype is important for treatment selection, disease prognosis, and family counseling.

Transcriptomics in tissue glucocorticoid sensitivity

BACKGROUND

Synthetic glucocorticoids are widely used in the treatment of several inflammatory, autoimmune and lymphoproliferative disorders. However, considerable variation in response to therapeutic doses of glucocorticoids has been documented among individuals. The aim of our study was to identify novel glucocorticoid sensitivity-determining genes using genome-wide expression profiling in healthy subjects.

METHODS

One hundred one healthy subjects [mean age ± standard error of the mean (SEM); 26.52 ± 0.50 years] were given 0.25 mg dexamethasone at midnight, and serum cortisol concentrations were determined at 08:00 hours the following morning. Subjects were stratified into the 10% most glucocorticoid-sensitive and 10% most glucocorticoid-resistant according to the serum cortisol concentrations. Genomic DNA, RNA and plasma samples were obtained in the 22 subjects one month later.

RESULTS

Transcriptomic analysis showed variability between glucocorticoid-resistant and glucocorticoid-sensitive subjects. One hundred thirty-three genes were upregulated and 49 downregulated in the glucocorticoid-resistant compared to the glucocorticoid-sensitive group. Further analysis revealed differences between 3 glucocorticoid-resistant and 3 glucocorticoid-sensitive subjects. The majority of the 1058 upregulated genes and 1139 downregulated genes were found to participate in telomere maintenance, systemic lupus erythematosus and Alzheimer's disease. Interestingly, Synuclein A, a key molecule in Parkinson's disease, was upregulated in the subgroup of glucocorticoid-sensitive subjects.

CONCLUSIONS

We have identified differences in tissue sensitivity to glucocorticoids among healthy subjects at the transcriptomic level. These differences are associated with differential expression of genes related to autoimmune and neurological disorders.

SUN-272 Persistent Hyperinsulinemic Hypoglycemia Due to Mutation in Hepatocyte Nuclear Factor 4A

Background: Congenital hyperinsulinism (HI) is the most common cause of hypoglycemia in children. Delay in diagnosis and or inadequate management can lead to brain damage. Persistent hyperinsulinemic hypoglycemia of infancy is a genetic disorder with both familial and sporadic form. Aim: To present the case of an infant with persistent hyperinsulinenic hypoglycemia due to HNF4A gene mutation, inherited by his mother who was perceived to have Diabetes Mellitus Type 2. Clinical presentation: A premature boy born at 35 weeks gestation by caesarian section due to mother’s hypertension, proteinuria and peripheral edema with birth weight of 2565gr and 44.5cm length. He was the first child of family and mother is referred to suffer from diabetes mellitus type 2 since 17 years of age treated with oral antidiabetic drugs. During pregnancy, optimal glycemic control was achieved after initiation of insulin therapy. After birth, at first 2 hours of life, blood glucose was 23mg/dl. Asymptomatic hypoglycemia persisted. During hypoglycemia arterial pH, lactic acid and cortisol were within reference range and insulin as ell c-peptide levels were elevated. Synachten test was normal. 30 minutes after glucagon administration, glucose level was increased by 48mg/dl and after 60 minutes glucose level was increased by 34 mg/dl. Five hours after feeding, glucose was 47mg/dl and diazoxide treatment was started (7.5 mg/kg/day). He responded well to diazoxide and daily dosage was decreased to 1mg/kg/day. Genetic testing was performed. Heterozygous mutation in c.998G>C, pR333P of HNF4A gene was identified to infant and his mother. The infant is now 8 months old and he continuous on diazoxide therapy growing well. The identification of the mutation clarified that the mother suffers from maturity- onset diabetes of the young (MODY) and not Diabetes Mellitus type 2. Conclusion: Early detection of HI is very important in order to prevent permanent sequelae. Genetic mutation testing should be performed in order to define best treatment approach. Family history of diabetes can elucidate that the affected gene is HNF4A or HNF1a. HI due to HNF4A mutations may be transient or persistent into childhood and is usually responsive to diazoxide therapy. MODY can develop during the second or third decade of life that is usually responsive to sulfonylurias. Reference: Stanley CA Perspective on the genetics and diagnosis of congenital hyperinsulinism disorders JCEM 2016; 101: 815-26

Adrenal steroids in female hypothyroid neonates: Unraveling an association between thyroid hormones & adrenal remodeling

CONTEXT

The adrenal gland undergoes significant remodeling during the neonatal period, an essential developmental process that still remains incompletely understood. With respect to control over the remodeling process and, specifically, the role of thyroid hormones (TH), no human studies have been published. The effect of both hypo- and hyper-thyroidism has only been evaluated in adults, focusing on the mature adrenal. Recently, Huang et al identified expression of the TH receptor β1 in the mouse adrenal X-zone and demonstrated that TH administration could alter the postnatal adrenal remodeling process.

OBJECTIVE

To address whether TH influence adrenal steroid profiles and adrenal remodeling during the neonatal period.

METHODS

We compared the adrenal steroid profile of a naturally occurring prototype, female neonates with severe congenital hypothyroidism (CH, n=22, upon diagnosis of CH), with that of euthyroid neonates (n=20).

RESULTS

Significantly higher levels of adrenal steroids (17-OH-progesterone, DHEAS, Δ4- androstenedione and testosterone) were measured in neonates with severe CH compared to euthyroid neonates, returning within normal range after euthyroid state had been established on L-thyroxine replacement therapy whereas cortisol levels did not differ. TSH values in the CH group were positively, while FT4 levels were negatively correlated with circulating adrenal steroids.

CONCLUSIONS

The hormonal profile of female neonates with severe CH suggests a more active adrenal fetal zone than controls. These data indirectly associate TH with the adrenal remodeling and maturation process in humans. Based on our results we suggest that severe hypothyroidism decelerates the involution of the adrenal fetal zone that normally occurs postnatally.

The Role of S-Palmitoylation of the Human Glucocorticoid Receptor (hGR) in Mediating the Nongenomic Glucocorticoid Actions

BACKGROUND

Many rapid nongenomic glucocorticoid actions are mediated by membrane-bound glucocorticoid receptors (GRs). S-palmitoylation is a lipid post-translational modification that mediates the membrane localization of some steroid receptors. A highly homologous amino acid sequence (663YLCM KTLLL671) is present in the ligand-binding domain of hGRα, suggesting that hGRα might also undergo S-palmitoylation.

AIM

To investigate the role of the motif 663YLCMKTLLL671 in membrane localization of the hGRα and in mediating rapid nongenomic glucocorticoid signaling.

METHODS AND RESULTS

We showed that the mutant receptors hGRαY663A, hGRαC665A and hGRαLL670/671AA, and the addition of the palmitoylation inhibitor 2-bromopalmitate did not prevent membrane localization of hGRα and co-localization with caveolin-1, and did not influence the biphasic activation of mitogen-activated protein kinase (MAPK) signaling pathway in the early time points. Finally, the hGRα was not shown to undergo S-palmitoylation.

CONCLUSIONS

The motif 663YLCMKTLLL671 does not play a role in membrane localization of hGRα and does not mediate the nongenomic glucocorticoid actions.

Increased glucocorticoid receptor expression in sepsis is related to heat shock proteins, cytokines, and cortisol and is associated with increased mortality

Background

The purposes of this study are to examine if the human glucocorticoid receptor (hGR) isoform-α mRNA and hGR protein expressions are deficient in the acute phase of sepsis (S) compared to systemic inflammatory response syndrome (SIRS) and healthy subjects (H) and to evaluate if the hGRα and hGR alterations are associated with cortisol changes and if they are related to (1) extracellular and intracellular heat shock proteins (HSP) 72 and 90α; (2) ACTH, prolactin, and interleukins (ILs); and (3) outcome.

Methods

Patients consecutively admitted to a university hospital intensive care unit (ICU) with S (n = 48) or SIRS (n = 40) were enrolled in the study. Thirty-five H were also included. Total mRNA was isolated from peripheral blood samples and cDNA was prepared. RT-PCR was performed. Intracellular hGR and HSP expression in monocytes and/or neutrophils was evaluated using four-colour flow cytometry. Serum prolactin, ACTH, and cortisol concentrations were also measured. ELISA was used to evaluate serum ILs and extracellular (e) HSPs (eHSP72, eHSP90α).

Results

hGR protein was higher in S compared to H and SIRS; hGRα mRNA was higher in S compared to H (p < 0.05). In sepsis, hGR protein and eHSP72 were higher among non-survivors compared to survivors (p < 0.05). The hGR MFI and hGRα mRNA fold changes were significantly related to each other (r_s = 0.64, p < 0.001). Monocyte hGR protein expression was positively correlated with extracellular and intracellular HSPs, cortisol, and ILs and negatively to organ dysfunction (p < 0.05). HSPs, hGR, and cortisol were able to discriminate sepsis from SIRS (AUROC > 0.85, p < 0.05). In sepsis, monocyte-hGR protein and eHSP72 were strong predictors of mortality (AUROC > 0.95, p < 0.04).

Conclusions

Acute-phase sepsis is associated with increased hGR expression and cortisol concentrations, possibly implying no need for exogenous steroids. At this stage, hGR is able to predict sepsis and outcome and is related to stress-activated bio-molecules and organ dysfunction.

Functional characterization of two novel germline mutations of the KCNJ5 gene in hypertensive patients without primary aldosteronism but with ACTH-dependent aldosterone hypersecretion

BACKGROUND

Germline mutations of the KCNJ5 gene encoding Kir3·4, a member of the inwardly rectifying K⁺ channel, have been identified in 'normal' adrenal glands, patients with familial hyperaldosteronism (FH) type III, aldosterone-producing adenomas (APAs) and sporadic cases of primary aldosteronism (PA).

OBJECTIVE

To present two novel KCNJ5 gene mutations in hypertensive patients without PA, but with Adrenocorticotropic hormone (ACTH)-dependent aldosterone hypersecretion.

DESIGN AND PATIENTS

Two hypertensive patients without PA, who exhibited enhanced ACTH-dependent response of aldosterone secretion, underwent genetic testing for the presence of the CYP11B1/CYP11B2 chimeric gene and KCNJ5 gene mutations. Genomic DNA was isolated from peripheral white blood cells, and the exons of the entire coding regions of the above genes were amplified and sequenced. Electrophysiological studies were performed to determine the effect of identified mutation(s) on the membrane reversal potentials. Structural biology studies were also carried out.

RESULTS

Two novel germline heterozygous KCNJ5 mutations, p.V259M and p.Y348N, were detected in the two subjects. Electrophysiological studies showed that the Y348N mutation resulted in significantly less negative reversal potentials, suggesting loss of ion selectivity, while the V259M mutation did not affect the Kir3.4 current. In the mutated structural biology model, the N348 mutant resulted in significant loss of the ability for hydrogen bonding, while the M259 mutant was capable of establishing weaker interactions. The CYP11B1/CYP11B2 chimeric gene was not detected.

CONCLUSIONS

These findings expand on the clinical spectrum of phenotypes associated with KCNJ5 mutations and implicate these mutations in the pathogenesis of hypertension associated with increased aldosterone response to ACTH stimulation.

Sequencing analysis of the human glucocorticoid receptor (NR3C1) gene in multiple sclerosis patients

Various specific human glucocorticoid receptor (NR3C1) gene polymorphisms have been described in multiple sclerosis (MS) patients and correlated with disease progression, susceptibility and aggressiveness. Herein, we investigated the presence of gene alterations in the entire coding region of the NR3C1 in MS patients of variable clinical status (CIS, RRMS and SPMS) and the association(s) of these alterations with severity of disease (EDSS), response to glucocorticoid (GC) treatment and clinical improvement. Sixty Caucasian Greek MS patients were included. Sequencing the coding sequences and intron-exon boundaries of the NR3C1 did not reveal the presence of mutation(s) in any of the MS patients. Three previously described polymorphisms were detected: p.N363S (rs6195), p.N766N (rs6196) and c.1469-16G>T (rs6188). None of the identified alleles/genotypes were found to be associated with the severity of disease, response to glucocorticoids and disease subtypes. Known polymorphism, such as ER22/23EK that has been previously detected in MS patients, was not detected. There is a considerable ethnicity-related variation in the frequency of the NR3C1 polymorphisms. Although a genetic basis of the glucocorticoid sensitivity exists in healthy population, in the presence of chronic inflammation and abundance of cytokines--such in MS patients--other factors appear to play a more important role in GC sensitivity.

Functional characterization of the hGRαT556I causing Chrousos syndrome

BACKGROUND

Chrousos syndrome is a rare pathologic condition characterized by generalized, partial resistance of target tissues to glucocorticoids and caused by inactivating mutations of the human glucocorticoid receptor (hGR) gene. A novel case of Chrousos syndrome has been reported in a patient with adrenal incidentaloma, who harboured a heterozygous point mutation in the hGR gene, which resulted in threonine (T) to isoleucine (I) substitution at amino acid position 556 in the ligand-binding domain of the receptor.

OBJECTIVE

To delineate the molecular mechanisms through which the mutant receptor hGRαT556I causes Chrousos syndrome.

DESIGN AND RESULTS

Compared with the wild-type receptor, the mutant receptor hGRαT556I demonstrated 50% reduction in its ability to transactivate glucocorticoid-responsive genes and in the affinity for the ligand, 30% increase in the ability to transrepress the nuclear factor-κB-target genes and a 3,4-fold delay in the cytoplasmic-to-nuclear translocation. The mutant receptor hGRαT556I did not exert a dominant negative effect upon the hGRα-mediated transcriptional activity; it preserved its ability to bind to DNA and interacted with the glucocorticoid receptor-interacting protein 1 coactivator mostly through its activation function-1 domain. Structural biology studies revealed that the T556I mutation caused disruption of the hydrogen bond formed by the T556 with the =O group of P637 backbone, which resulted in a significant relocation of the P637-bearing loop. This conformational alteration affected the local 3D arrangement of the receptor and hence the electrostatic surface of the region.

CONCLUSIONS

The hGRαT556I causes Chrousos syndrome by impairing multiple steps of the glucocorticoid signal transduction pathway.

Recent advances in the molecular mechanisms causing primary generalized glucocorticoid resistance

Primary Generalized Glucocorticoid Resistance is a rare condition characterized by generalized, partial, target tissue insensitivity to glucocorticoids owing to inactivating mutations, insertions or deletions in the human glucocorticoid receptor (hGR) gene (NR3C1). Recent advances in molecular and structural biology have enabled us to elucidate the molecular mechanisms of action of the mutant receptors and to understand how certain conformational alterations of the defective hGRs result in generalized glucocorticoid resistance. Furthermore, our ever-increasing understanding of the molecular mechanisms of glucocorticoid action indicates that the glucocorticoid signaling pathway is a stochastic system that plays a fundamental role in maintaining both basal and stress-related homeostasis. In this review, we summarize the clinical manifestations and molecular pathogenesis of Primary Generalized Glucocorticoid Resistance, we present our recent findings from the functional characterization of three novel heterozygous point mutations in the NR3C1 gene, and we discuss the diagnostic approach and therapeutic management of the condition. When the condition is suspected, we recommend sequencing analysis of the NR3C1 gene as well as of other genes encoding proteins involved in the glucocorticoid signal transduction. The tremendous progress of next-generation sequencing will undoubtedly uncover novel hGR partners or cofactors.

Transient generalized glucocorticoid hypersensitivity

BACKGROUND

Transient generalized glucocorticoid hypersensitivity is a rare disorder characterized by increased tissue sensitivity to glucocorticoids and compensatory hypo-activation of the hypothalamic-pituitary-adrenal axis. The condition itself and the underlying molecular mechanisms have not been elucidated.

OBJECTIVE

To present the clinical manifestations, endocrinologic evaluation and transcriptomic profile in a patient with transient generalized glucocorticoid hypersensitivity.

DESIGN AND RESULTS

A 9-year-old girl presented with an 8-month history of clinical manifestations suggestive of Cushing syndrome. Endocrinologic evaluation revealed undetectable 08:00 h ACTH (<1 pg/mL) and cortisol (0·025 μg/dL) concentrations, which remained decreased throughout the 24-h period and did not respond to stimulation with ovine CRH. The disease gradually resolved spontaneously over the ensuing 3 months. Sequencing of the human glucocorticoid receptor gene revealed no mutations or polymorphisms. Western blot analysis in peripheral blood mononuclear cells revealed equal protein expression of hGRα of the patient in the disease and postresolution phases compared with a control subject. Transcriptomic analysis in peripheral blood mononuclear cells in the disease and postresolution phases identified 903 differentially expressed genes. Of these, 106 genes were up-regulated and 797 were down-regulated in the disease compared with the resolution phase. Bioinformatics analysis on the differentially expressed gene networks revealed Nuclear Factor-κB as the predominant transcription factor influencing the expression of the majority of differentially expressed genes.

CONCLUSIONS

Our findings indicate that a transient postreceptor defect, or a virus- or bacterium-encoded molecule, may have enhanced glucocorticoid signal transduction, leading to transient generalized glucocorticoid hypersensitivity and hypo-activation of the HPA axis.

A novel mutation of the hGR gene causing Chrousos syndrome

BACKGROUND

Natural mutations in the human glucocorticoid receptor (hGR, NR3C1) gene cause Chrousos syndrome, a rare condition characterized by generalized, partial, target-tissue insensitivity to glucocorticoids.

OBJECTIVE

To present a new case of Chrousos syndrome caused by a novel mutation in the hGR gene, and to elucidate the molecular mechanisms through which the natural mutant receptor affects glucocorticoid signal transduction.

DESIGN AND RESULTS

The index case presented with hirsutism, acne, alopecia, anxiety, fatigue and irregular menstrual cycles, but no clinical manifestations suggestive of Cushing's syndrome. Endocrinologic evaluation revealed elevated 08:00 h plasma adrenocorticotropic hormone, serum cortisol and androstenedione concentrations and increased urinary free cortisol excretion. The patient harbored a novel A > G transition at nucleotide position 2177, which resulted in histidine (H) to arginine (R) substitution at amino acid position 726 of the receptor (c.2177A > G, p.H726R). Compared with the wild-type receptor, the mutant receptor hGRαH726R demonstrated decreased ability to transactivate glucocorticoid-responsive genes and to transrepress the nuclear factor-κB signalling pathway, displayed 55% lower affinity for the ligand and a four-fold delay in nuclear translocation, and interacted with the glucocorticoid receptor-interacting protein 1 coactivator mostly through its activation function-1 domain. Finally, a 3-dimensional molecular modelling study of the H726R mutation revealed a significant structural shift in the rigidity of helix 10 of the receptor, which resulted in reduced flexibility and decreased affinity of the mutant receptor for binding to the ligand.

CONCLUSIONS

The natural mutant receptor hGRαH726R impairs multiple steps of glucocorticoid signal transduction, thereby decreasing tissue sensitivity to glucocorticoids.

Stress-induced Aldosterone Hyper-Secretion in a Substantial Subset of Patients With Essential Hypertension

CONTEXT

Aldosterone (ALD) secretion is regulated mainly by angiotensin II, K(+), and adrenocorticotropic hormone (ACTH). Mineralocorticoid receptor antagonists (MRAs) have effectively been used for the treatment of patients with hypertension who do not have primary aldosteronism (PA).

OBJECTIVE

We tested whether chronic stress-related ACTH-mediated ALD hypersecretion and/or zona glomerulosa hypersensitivity could be implicated in the pathogenesis of essential hypertension (ESHT).

PATIENTS AND METHODS

One hundred thirteen hypertensives without PA and 61 normotensive controls underwent an ultralow-dose (0.03-μg) ACTH stimulation and a treadmill test. Patients with ALD hyper-response according to the cutoffs obtained from controls received treatment with MRAs and underwent genomic DNA testing for the presence of the CYP11B1/CYP11B2 chimeric gene and KCNJ5 gene mutations. A control group of 22 patients with simple ESHT received treatment with MRAs.

RESULTS

Based on the cutoffs of ALD and aldosterone-to-renin ratio (ARR) post-ACTH stimulation obtained from controls, 30 patients (27%) exhibited an ALD but not cortisol (F) hyper-response (HYPER group). This group had no difference in basal ACTH/renin (REN) concentrations compared with controls and the 83 patients with hypertension (73%) without an ALD hyper-response to ACTH stimulation. Patients in the HYPER group demonstrated significantly higher ALD concentrations, ARR, and ALD/ACTH ratio (AAR) in the treadmill test. Treatment with MRAs alone produced normalization of blood pressure in these patients whereas patients with hypertension with neither PA nor ALD hyper-response to ACTH stimulation who served as a control group failed to lower blood pressure. Also, two novel germline heterozygous KCNJ5 mutations were detected in the HYPER group.

CONCLUSIONS

A number of patients with hypertension without PA show ACTH-dependent ALD hyper-secretion and benefit from treatment with MRAs. This could be related to chronic stress via ACTH hyper secretion and/or gene-mutations increasing the zona glomerulosa responsiveness to excitatory stimuli.

The spectrum of clinical, hormonal and molecular findings in 280 individuals with nonclassical congenital adrenal hyperplasia caused by mutations of the CYP21A2 gene

BACKGROUND

Nonclassical congenital adrenal hyperplasia (NC-CAH) is caused by mutations of the CYP21A2 gene. The clinical manifestations and hormonal derangements of NC-CAH are quite variable.

OBJECTIVES

(i) To define the phenotype and its relation to genotype according to gender and age and (ii) to evaluate the validity of currently applied hormonal criteria for establishing the diagnosis of NC-CAH.

PATIENTS AND METHODS

The clinical, hormonal and molecular data of 280 subjects (235 female) with NC-CAH and a median age of 17·6 years were analysed. CYP21A2 genotyping was performed in all subjects.

RESULTS

The majority of females aged less than 8 years presented with premature pubarche (88·3%), while those older than 8 presented with a polycystic ovary-like phenotype (63·2%). A total of 7·7% of the females and 51·1% of the males were asymptomatic at the time of diagnosis. In the total group, 50·4% of the subjects were compound heterozygotes for one classical (C) and one nonclassical (NC) mutation, while 46% of the alleles studied carried the p.V281L mutation. Basal 17OHP values were below 6 nm (2 ng/ml) in 2·1% of the subjects with NC-CAH, but none had peak 17OHP values post-ACTH lower than 30 nm (10 ng/ml).

CONCLUSIONS

NC-CAH has a variable phenotype depending on the age, gender and the presence of a classical mutation. A peak cut-off value of 17OHP post-ACTH lower than 30 nm excludes the diagnosis of NC-CAH, whereas basal 17OHP <6 nm may represent a false-negative result. A significant number of patients harboured a classical mutation, a finding which requires genotyping of the partner for genetic counselling.

A novel point mutation of the human glucocorticoid receptor gene causes primary generalized glucocorticoid resistance through impaired interaction with the LXXLL motif of the p160 coactivators: dissociation of the transactivating and transreppressive activities

CONTEXT

Primary generalized glucocorticoid resistance is a rare genetic disorder characterized by generalized, partial, target-tissue insensitivity to glucocorticoids. The molecular basis of the condition has been ascribed to inactivating mutations in the human glucocorticoid receptor (hGR) gene.

OBJECTIVE

The objective of the study was to present three new cases caused by a novel mutation in the hGR gene and to delineate the molecular mechanisms through which the mutant receptor impairs glucocorticoid signal transduction.

DESIGN AND RESULTS

The index case (father) and his two daughters presented with increased urinary free cortisol excretion and resistance of the hypothalamic-pituitary-adrenal axis to dexamethasone suppression in the absence of clinical manifestations suggestive of Cushing syndrome. All subjects harbored a novel, heterozygous, point mutation (T→G) at nucleotide position 1724 of the hGR gene, which resulted in substitution of valine by glycine at amino acid 575 of the receptor. Compared with the wild-type receptor, the hGRαV575G demonstrated a significant (33%) reduction in its ability to transactivate the mouse mammary tumor virus promoter in response to dexamethasone, a 50% decrease in its affinity for the ligand, and a 2.5-fold delay in nuclear translocation. Although it did not exert a dominant negative effect on the wild-type receptor and preserved its ability to bind to DNA, hGRαV575G displayed significantly enhanced (∼80%) ability to transrepress the nuclear factor-κΒ signaling pathway. Finally, the mutant receptor hGRαV575G demonstrated impaired interaction with the LXXLL motif of the glucocorticoid receptor-interacting protein 1 coactivator in vitro and in computer-based structural simulation via its defective activation function-2 (AF-2) domain.

CONCLUSIONS

The natural mutant receptor hGRαV575G causes primary generalized glucocorticoid resistance by affecting multiple steps in the glucocorticoid signaling cascade, including the affinity for the ligand, the time required for nuclear translocation, and the interaction with the glucocorticoid-interacting protein-1 coactivator.

The spectrum of HNF1A gene mutations in Greek patients with MODY3: relative frequency and identification of seven novel germline mutations

OBJECTIVE

Maturity-Onset Diabetes of the Young (MODY) is the most common type of monogenic diabetes accounting for 1-2% of the population with diabetes. The relative incidence of HNF1A-MODY (MODY3) is high in European countries; however, data are not available for the Greek population. The aims of this study were to determine the relative frequency of MODY3 in Greece, the type of the mutations observed, and their relation to the phenotype of the patients.

DESIGN AND METHODS

Three hundred ninety-five patients were referred to our center because of suspected MODY during a period of 15 yr. The use of Denaturing Gradient Gel Electrophoresis of polymerase chain reaction amplified DNA revealed 72 patients carrying Glucokinase gene mutations (MODY2) and 8 patients carrying HNF1A gene mutations (MODY3). After using strict criteria, 54 patients were selected to be further evaluated by direct sequencing or by multiplex ligation probe amplification (MLPA) for the presence of HNF1A gene mutations.

RESULTS

In 16 unrelated patients and 13 of their relatives, 15 mutations were identified in the HNF1A gene. Eight of these mutations were previously reported, whereas seven were novel. Clinical features, such as age of diabetes at diagnosis or severity of hyperglycemia, were not related to the mutation type or location.

CONCLUSIONS

In our cohort of patients fulfilling strict clinical criteria for MODY, 12% carried an HNF1A gene mutation, suggesting that defects of this gene are responsible for a significant proportion of monogenic diabetes in the Greek population. No clear phenotype-genotype correlations were identified.

A novel point mutation in the DNA-binding domain (DBD) of the human glucocorticoid receptor causes primary generalized glucocorticoid resistance by disrupting the hydrophobic structure of its DBD

CONTEXT

Primary generalized glucocorticoid resistance is a rare genetic condition characterized by partial end-organ insensitivity to glucocorticoids. Most affected subjects present with clinical manifestations of mineralocorticoid and androgen excess. The condition has been associated with inactivating mutations in the human glucocorticoid receptor (hGR) gene, which impair the molecular mechanisms of hGRα action, thereby reducing tissue sensitivity to glucocorticoids.

OBJECTIVE

ΤHE aim of our study was to investigate the molecular mechanisms through which one previously described natural heterozygous V423A mutation, the second mutation detected in the DNA-binding domain (DBD) of the hGRα, affects glucocorticoid signal transduction.

DESIGN AND RESULTS

Compared with the wild-type receptor, hGRαV423A demonstrated a 72% reduction in its ability to transactivate the glucocorticoid-inducible mouse mammary tumor virus promoter in response to dexamethasone. The hGRαV423A receptor showed a significant reduction in its ability to bind to glucocorticoid-response elements of glucocorticoid-responsive genes, owing to structural alterations of the DBD confirmed by computer-based structural analysis. In addition, hGRαV423A demonstrated a 2.6-fold delay in nuclear translocation following exposure to the ligand, although it did not exert a dominant negative effect on the wild-type hGRα, had a similar affinity to the ligand with the wild-type receptor, and displayed a normal interaction with the GRIP1 coactivator in vitro.

CONCLUSIONS

The natural mutant receptor hGRαV423A causes primary generalized glucocorticoid resistance by affecting multiple steps in the cascade of glucocorticoid receptor action, which primarily involve decreased ability to bind to target glucocorticoid response elements and delayed translocation into the nucleus.

Pituitary stalk interruption syndrome and isolated pituitary hypoplasia may be caused by mutations in holoprosencephaly-related genes

CONTEXT

Holoprosencephaly (HPE) is a developmental defect characterized by wide phenotypic variability, ranging from minor midline malformations (eg, single central incisor) to severe deformities. In 10-15% of HPE patients, mutations in specific genes have been identified (eg, SHH, TGIF, SIX3). Pituitary stalk interruption syndrome (PSIS) constitutes a distinct abnormality of unknown pathogenesis, whereas isolated pituitary hypoplasia (IPH) has been linked to various developmental genes.

OBJECTIVE

Three of our patients with PSIS had a single central incisor, a malformation encountered in some HPE cases. Based on this observation, we initiated a search for mutations in HPE-associated genes in 30 patients with PSIS or IPH.

DESIGN AND PARTICIPANTS

The entire coding region of the TGIF, SHH, and SIX3 genes was sequenced in patients with combined pituitary hormone deficiency associated with either PSIS or IPH and in healthy controls.

RESULTS

Two novel mutations in the HPE-related genes were detected (ie, c.799 C>T, p.Q267X in the TGIF gene, and c.1279G>A, p.G427R in the SHH gene) in 2 of our patients. The overall incidence of HPE-related gene mutations in our nonsyndromic and nonchromosomal patients was 6.6%. No molecular defect in the SIX3 gene was detected in our cohort.

CONCLUSIONS

The data suggest that HPE-related gene mutations are implicated in the etiology of isolated pituitary defects (PSIS or IPH). Alternatively, PSIS or IPH may constitute mild forms of an expanded HPE spectrum.

Long-term clinical data and molecular defects in the STAR gene in five Greek patients

CONTEXT

Steroidogenic acute regulatory (STAR) gene mutations lead to adrenal and gonadal failure. Interesting, though as yet unexplained, features are the formation of ovarian cysts and the potential presence of CNS findings.

OBJECTIVE

To report biochemical, genetic, and long-term clinical data in five Greek patients from four different families with STAR gene defects (three 46,XX and two 46,XY).

METHODS AND RESULTS

All patients presented in early infancy with adrenal insufficiency. The STAR gene mutation c.834del11bp, detected in three of our patients, completely alters the carboxyl end of the STAR protein and has not thus far been described in other population groups. These three patients belong to three separate families, possibly genetically related, as they live in different villages located in a small region of a Greek island. However, their interrelationship has not been proven. A second mutation, p.W250X, detected in our fourth family, was previously described only in two Serbian patients. Ovarian cysts were detected ultrasonographically in our 46,XX patients and seemed to respond to a low dose of a contraceptive. The histology of an excised ovarian cyst was diagnosed as a corpus luteum (CL) cyst. In two out of the four patients who had undergone brain magnetic resonance imaging, asymptomatic Chiari-1 malformation was observed.

CONCLUSIONS

The occurrence of STAR gene mutation c.834del11bp in three families living in a restricted geographic region could indicate either a founder effect or simply reflect a spread of this defect in a highly related population. The ovarian histological findings suggest that ovarian cysts detected ultrasonographically in 46,XX individuals with STAR gene defects may be CL cysts. The Chiari-1 malformation in two of our patients may be part of the STAR gene mutation phenotype. Nevertheless, more data are needed to confirm or disprove the existence of specific CNS pathology in patients with STAR gene mutations.

PROP-1 gene mutations in a 63-year-old woman presenting with osteoporosis and hyperlipidaemia

PROP-1 gene mutations have been reported as a cause of combined pituitary hormone deficiency. Physical and hormonal phenotypes of affected individuals are variable. We report a 63-year-old female who presented with osteoporosis. She was short, did not enter puberty spontaneously and had primary amenorrhea. Biochemical evaluation revealed secondary hypothyroidism and mixed hyperlipidaemia, while dynamic testing of pituitary function was diagnostic of hypopituitarism. Bone density in the lumbar spine disclosed osteoporosis. DNA analysis showed that the patient was homozygote for the R73H mutation of the PROP-1 gene. The unfavourable long-term course of an untreated patient with PROP-1 gene mutation emphasizes the need for early aetiologic classification and proper management and follow-up of patients with short stature and/or disturbances of pubertal development.

A novel point mutation in the KCNJ5 gene causing primary hyperaldosteronism and early-onset autosomal dominant hypertension

CONTEXT

Aldosterone production in the adrenal zona glomerulosa is mainly regulated by angiotensin II, [K(+)], and ACTH. Genetic deletion of subunits of K(+)-selective leak (KCNK) channels TWIK-related acid sensitive K(+)-1 and/or TWIK-related acid sensitive K(+)-3 in mice results in primary hyperaldosteronism, whereas mutations in the KCNJ5 (potassium inwardly rectifying channel, subfamily J, member 5) gene are implicated in primary hyperaldosteronism and, in certain cases, in autonomous glomerulosa cell proliferation in humans.

OBJECTIVE

The objective of the study was to investigate the role of KCNK3, KCNK5, KCNK9, and KCNJ5 genes in a family with primary hyperaldosteronism and early-onset hypertension.

PATIENTS AND METHODS

Two patients, a mother and a daughter, presented with severe primary hyperaldosteronism, bilateral massive adrenal hyperplasia, and early-onset hypertension refractory to medical treatment. Genomic DNA was isolated and the exons of the entire coding regions of the above genes were amplified and sequenced. Electrophysiological studies were performed to determine the effect of identified mutation(s) on the membrane reversal potentials.

RESULTS

Sequencing of the KCNJ5 gene revealed a single, heterozygous guanine to thymine (G → T) substitution at nucleotide position 470 (n.G470T), resulting in isoleucine (I) to serine (S) substitution at amino acid 157 (p.I157S). This mutation results in loss of ion selectivity, cell membrane depolarization, increased Ca(2+) entry in adrenal glomerulosa cells, and increased aldosterone synthesis. Sequencing of the KCNK3, KCNK5, and KCNK9 genes revealed no mutations in our patients.

CONCLUSIONS

These findings explain the pathogenesis in a subset of patients with severe hypertension and implicate loss of K(+) channel selectivity in constitutive aldosterone production.

Late diagnosis of 5alpha steroid-reductase deficiency due to IVS12A>G mutation of the SRD5a2 gene in an adolescent girl presented with primary amenorrhea

BACKGROUND

The clinical spectrum of 5α-reductase deficiency, caused by mutations in the SRD5A2 gene, ranges from complete female appearance of the external genitalia at birth to nearly complete male phenotype.

CASE REPORT

A 14-year-old girl presented with primary amenorrhea (PA) and lack of breast development. She was 173 cm in height, had an increased amount of pubic hair and clitoromegaly (3 cm), with a 4 cm blind vaginal pouch. Gonads were palpable in the inguinal canal bilaterally and no uterus was identified on ultrasound. Chromosomal analysis showed a 46,XY karyotype. The Testosterone/DHT ratio was high (16.5) and further increased to 29.4 after stimulation with hCG, thus favouring the diagnosis of 5α-reductase deficiency. Since the issue of gender change was not considered, gonadectomy was performed followed by successful feminisation with hormonal replacement therapy.

GENETIC STUDIES

Molecular analysis of the SRD5A2 gene by DNA sequencing of all 5 exons revealed the presence of the splice mutation A>G at position -2 of the acceptor site of intron 1/exon 2 (IVS1-2A>G) in homozygosity. Both non-consanguineous parents were found to be heterozygotes for this mutation.

CONCLUSIONS

Although rare, SRD5A2 gene defect should be suspected in any girl presenting with PA and virilisation at puberty. The IVS1-2A>G mutation of the SRD5A2 gene predominates in Greek-Cypriot patients with 5α-reductase deficiency and very likely reflects a founder effect.

The IVS1-2A>G mutation in the SRD5A2 gene predominates in Cypriot patients with 5α reductase deficiency

BACKGROUND

5α steroid reductase deficiency (5αSRD) is an autosomal recessive enzymatic deficiency and mutations in the 5α steroid reductase type 2 gene (SRD5A2) result in male pseudohermaphrodism caused by decreased dihydrotestosterone (DHT) synthesis.

AIM

To identify the specific mutations of the SRD5A2 gene in Cypriot patients with 5αSRD.

SUBJECTS AND METHODS

Five unrelated patients with 46,XY karyotype were examined. Four of them were born with ambiguous genitalia and 1 patient, who was raised as girl, presented with primary amenorrhea. The hCG test was informative (elevated testosterone/DHT) of 5αSRD in 3 out of 4 subjects. Sequencing of the SRD5A2 gene was completed for all patients. Genomic DNA was also isolated from a total of 204 healthy unrelated Cypriot subjects. Screening for the IVS1-2A>G mutation was performed by using direct sequencing and restriction enzyme analysis.

RESULTS

The IVS1-2A>G was identified in homozygosity in 3 patients and in a compound heterozygote state in the other 2 patients, in combination with p.P181L and p.R171S in exon 3, respectively. The carrier frequency in the Cypriot population for the IVS1-2A>G mutation was estimated to be 0.98% or 2 in 204.

CONCLUSIONS

The same IVS1-2A>G mutation in the SRD5A2 gene seems to characterize all Cypriot patients with 5αSRD diagnosed so far. Furthermore this relatively rare genetic defect, which has only been reported previously in a single case in the Eastern Mediterranean region, is very likely to be the result of a founder effect.

Conception and pregnancy outcome in a patient with 11-bp deletion of the steroidogenic acute regulatory protein gene

OBJECTIVE

To report the pregnancy outcome of a patient with congenital lipoid adrenal hyperplasia (CLAH) due to an 11-bp deletion of the steroidogenic acute regulatory protein (StAR) gene.

DESIGN

Case report.

SETTING

University-based pediatric endocrinology unit and private IVF clinic.

PATIENT(S)

A 24-year-old woman homozygous for a StAR gene deletion, married to a man heterozygous for the same molecular defect.

INTERVENTION(S)

Ovarian stimulation, oocyte retrieval followed by IVF, blastomere biopsy, preimplantation genetic diagnosis, and additional estrogen support until placental function initiation.

MAIN OUTCOME MEASURE(S)

Normal pregnancy outcome and delivery of a healthy newborn.

RESULT(S)

A female patient with CLAH gave birth to a normal newborn after IVF and preimplantation genetic diagnosis.

CONCLUSION(S)

Pregnancy is feasible in patients with StAR gene mutations, provided that extra estrogens are offered until placental function ensues.

Pituitary size fluctuation in long-term MR studies of PROP1 deficient patients: A persistent pathophysiological mechanism?

Inactivating PROP1 gene alterations are responsible for over 50% of familial combined pituitary hormone deficiency cases. Pituitary enlargement followed by regression and subnormal pituitary size has been documented in a number of PROP1 deficient patients. Data derived from PROP1 deficient mice (Ames dwarfs) have revealed some of the underlying cellular mechanisms. Nevertheless, long-term magnetic resonance imaging (MRI) findings in two PROP1 deficient patients suggest the evolution of pituitary pathology as more complex and persistent than previously described. Patient A had enlarged pituitary gland (pituitary height: 9-10 mm), demonstrated by serial MRI carried out from age 5 to 8.5 yr, small pituitary gland (4 mm) at age 10 yr and pituitary enlargement (11 mm) at age 19 yr. Patient B had a pituitary gland of normal size at age 7 yr (5 mm), whereas at age 14.3 and 16.3 yr, an enlarged pituitary gland was disclosed (10 and 11 mm, respectively). Both series of events are suggestive of a persistent pathophysiological mechanism in the pituitary gland of patients with PROP1 gene defects. Therefore, long-term pituitary follow-up by MRI in such patients may be necessary even in the case of a small or normal pituitary gland. It must be noted that current data from the Ames dwarf mouse cannot fully explain the observed pituitary size fluctuation.

Ovulation induction and successful pregnancy outcome in two patients with Prop1 gene mutations

OBJECTIVE

To describe ovulation induction and pregnancy outcome in a unique model of genetically determined combined pituitary hormone deficiency (CPHD), with respect to the necessity for GH substitution therapy.

DESIGN

Case report.

SETTING

Academic units.

PATIENT(S)

Two patients with childhood onset of CPHD (GH, PRL, TSH, LH, FSH) caused by a genetic defect (GA296del mutation) of the Prop1 gene.

MAIN OUTCOME MEASURE(S)

Ovulation, pregnancy outcome, and fetal growth.

RESULT(S)

Successful pregnancy outcome and delivery of normal, full-term newborns were achieved in both patients with the use of gonadotropins and L-T(4). Growth hormone supplementation was not necessary. No lactation was observed.

CONCLUSION(S)

Patients with Prop1 gene mutations constitute a unique model for studying the role of GH and PRL in ovulation, pregnancy, and fetal growth. Our data indicate that for women with CPHD, ovulation and pregnancy are possible with a classic regimen for hypogonadotropic hypogonadism, without the need for GH substitution therapy.

Pituitary magnetic resonance imaging in 15 patients with Prop1 gene mutations: pituitary enlargement may originate from the intermediate lobe

Pituitary morphology in patients with Prop1 gene mutations varies. Most patients demonstrate a normal or small pituitary gland. Occasionally, pituitary enlargement of undetermined origin has also been detected. In the present study we use long-term magnetic resonance imaging findings to characterize the morphological abnormalities of the pituitary gland in 15 patients (aged 2.5-45 yr) with combined pituitary hormone deficiency caused by Prop1 gene mutations (GA296del/GA296del in seven, GA296del/A150del in two, A150del/A150del in five, and GA296del/R73H in one patient) and attempt to uncover the origin and nature of the pituitary enlargement. Small pituitary gland was detected in seven patients (25.2 +/- 14.4 yr of age), normal pituitary size in three patients (10.2 +/- 5.8 yr of age), and pituitary enlargement in five patients (6.5 +/- 2.7 yr of age). The pituitary enlargement consisted of a nonenhancing mass lesion interposed between the normally enhancing anterior lobe and the neurohypophysis. The pituitary stalk was displaced anteriorly, whereas the neurohypophysis was orthotopic, displaying a normal signal. Spontaneous regression of the mass lesion with normalization of the pituitary stalk position was observed in three patients. Our data indicate that although a small pituitary gland is usually observed in older subjects, a significant number of young patients with Prop1 gene mutations demonstrate pituitary enlargement with subsequent regression. The distinct magnetic resonance imaging characteristics of the pituitary enlargement in our patients in conjunction with pertinent data from Prop1-deficient mice suggest that the mass causing the pituitary enlargement most likely originates from the intermediate lobe.

Prolonged jaundice and hypothyroidism as the presenting symptoms in a neonate with a novel Prop1 gene mutation (Q83X)

OBJECTIVE

To identify the genetic defect in a neonate presented with prolonged jaundice and central hypothyroidism.

DESIGN

Central hypothyroidism was detected in a neonate initially examined for prolonged jaundice, and levothyroxine therapy was initiated. Direct sequencing of the Prop1 gene was carried out and pituitary function and morphology were evaluated using hormonal testing and magnetic resonance imaging (MRI) respectively.

METHODS

Dynamic hormonal testing was carried out using established methodologies. Hormones were determined by RIA or chemiluminescence immunoassays. Genomic analysis of the Prop1 gene was performed by direct sequencing. MRI protocol: sagittal spin echo T2-weighted scans 2500/90 (TR/TE), plain and contrast-enhanced sagittal and coronal spin echo T1-weighted scans 500/20 (TR/TE).

RESULTS

Low thyroid hormones (coupled with lack of TSH rise), low GH, normal cortisol and normal prolactin values were detected. Direct sequencing revealed the presence of two mutations in the Prop1 gene: GA296del and Q83X. The Q83X was further confirmed by PvuII restriction digestion and represented a novel Prop1 gene mutation, which was not detected in 100 controls tested. Pituitary enlargement was detected, with respect to normal-for-age controls.

CONCLUSIONS

(i) The Q83X mutation extends the spectrum of Prop1 gene mutations; (ii) central hypothyroidism in a neonate might constitute the initial sign of Prop1 gene defect; (iii) the patient is the youngest individual with Prop1 gene defect and pituitary enlargement presented to date; and (iv) early detection of Prop1 gene mutations facilitates genetic counseling and ensures prompt management of the anticipated hormonal insufficiencies.

Low TSH congenital hypothyroidism: identification of a novel mutation of the TSH beta-subunit gene in one sporadic case (C85R) and of mutation Q49stop in two siblings with congenital hypothyroidism

Isolated congenital hypothyroidism resulting from mutation of the TSH beta-subunit gene, has rarely been reported. In the present article, we report a new mutation (C85R) in exon 3 of the TSH beta-subunit gene in one sporadic case and the mutation Q49stop in two siblings with congenital hypothyroidism. The novel mutation is a T to C transition at codon 85, resulting in a change of cysteine to arginine (C85R) of the ss-subunit. Because the cysteine residues of all glycoproteins are highly conserved, this mutation is expected to result in conformational changes of the ss-subunit, rendering it incapable to form a functional heterodimer with the alpha-subunit. The second mutation described is a C to T transition resulting in a premature stop at codon 49 (Q49stop), leading to the formation of a truncated protein. Although the two siblings reported herein carried the same mutation, they had slightly modified clinical and biochemical phenotype. The mutation C85R and the previously described E11stop have, thus far, exclusively been detected in Greek patients. The Q49stop mutation initially detected in Greek patients was subsequently identified in an Egyptian girl and most recently in two Turkish siblings. These three reports possibly indicate the presence of a mutational hot spot on the TSH beta-subunit gene. Hence, with the novel mutation herein reported, a total of five mutations of the TSH beta-subunit gene are recognized as a cause of low-TSH congenital hypothyroidism worldwide.

Insufficient adrenarche in patients with combined pituitary hormone deficiency caused by a PROP-1 gene defect

Adrenarche was evaluated in five patients, aged 17.4 +/- 3 years, with combined pituitary hormone deficiency (CPHD), caused by a PROP-1 gene defect. Adrenocorticotrophic hormone (ACTH), cortisol and dehydroepiandrosterone sulfate (DHEAS) were determined prior to and following the administration of corticotropin-releasing hormone (CRH) in four of the five patients, while only basal values of ACTH, cortisol and DHEAS were determined in the fifth. In the four patients in whom a CRH test was carried out, the mean basal values of cortisol, ACTH and DHEAS were 289 +/- 140 nmol/l, 4.5 +/- 1.7 pmol/l and 0.26 +/- 0.36 micromol/l, respectively. The corresponding post-CRH peak values were 584 +/- 204 nmol/l, 12.7 +/- 3.9 pmol/l and 0.43 +/- 0.41 micromol/l. In the fifth patient, basal ACTH, cortisol and DHEAS values were 4 pmol/l, 411 nmol/l, and 2.33 micromol/l, respectively. Thus the basal and post CRH values of DHEAS (a marker of adrenarche) were low for age, while basal and post-CRH cortisol and ACTH values were within normal limits. For the interpretation of these findings two hypotheses can be proposed: 1) The PROP-1 gene is only expressed in the pituitary, and the role of PROP-1 is related to the maturation of the cells which synthesize the presumed adrenal androgen stimulating hormone (AASH). 2) The PROP-1 gene is also expressed in the adrenal cortex and, when defective, the zona reticularis does not function appropriately. Regardless of the interpretation

Insulin dependent diabetes mellitus (IDDM) and autoimmune thyroiditis in a boy with a ring chromosome 18: additional evidence of autoimmunity or IDDM gene(s) on chromosome 18

A 4 year 3 month old boy with insulin dependent diabetes mellitus (IDDM), autoimmune thyroiditis, slight mental retardation, facial dysmorphism, and a de novo ring chromosome 18 (deletion 18q22.3-18qter) is described. This unique association of defects could represent a chance association. Alternatively, the clinical features could be the result of the chromosomal aberration. If so, one could speculate that a gene or genes on chromosome 18 might act as a suppressor or activator of the autoimmune process by itself or in concert with other IDDM loci.