Pituitary Stalk Interruption Syndrome: From Clinical Findings to Pathogenesis

Two Cases of Late Diagnosis Pituitary Stalk Interruption Syndrome and Literature Review

Background

Pituitary stalk interruption syndrome (PSIS) is a rare congenital condition that includes the triad of a thin pituitary stalk, an ectopic posterior pituitary gland, and an absent or hypoplastic anterior pituitary gland and is usually diagnosed in infancy. This report presents two cases of late diagnosis of PSIS and a literature review of the relevant cases. The objective is to update data on such an uncommon syndrome to avoid the consequences of pituitary dysfunction including short stature, impaired cognitive function, negative impact on bone health, adrenal crises and delayed puberty.

Case Report

In this paper, we report on two cases of late diagnosis of PSIS with a history of growth hormone deficiency. The first case is a 21-year-old female presenting with generalized fatigability, dizziness and delayed puberty, while the second case is a 19-year-old female presenting with secondary amenorrhea. The hormonal profile of the first patient revealed panhypopituitarism; the second case had growth hormone deficiency subsequently had secondary hypogonadism with intact thyroid and adrenal functions. The diagnosis of PSIS was confirmed by magnetic resonance imaging (MRI), and both cases were treated with hormone supplements. Progress was also tracked through planned follow-up sessions. To the best of our knowledge, this is the first case series of such late diagnosis PSIS from Saudi Arabia.

Conclusion

The key message of this paper is that rare etiologies such as PSIS should be kept in mind, especially for young patients presenting with clinical evidence of pituitary hormonal deficiencies, and MRI should be considered to confirm diagnosis. The early diagnosis, hormonal replacement, and long-term follow-up are crucial to reducing negative impacts of pituitary hormonal deficiencies.

Risk factors and prediction model of metabolic disorders in adult patients with pituitary stalk interruption syndrome

Pituitary stalk interruption syndrome (PSIS) is an infrequently occurring congenital condition, and there exists a dearth of systematic investigative work focusing on the clinical features and long-term outcomes in adult patients. Individuals who have reached adulthood with PSIS are at an increased risk of developing metabolic disorders, including metabolic syndrome (MS) and non-alcoholic fatty liver disease (NAFLD) or metabolic dysfunction associated fatty liver disease (MAFLD), which are also one of the main factors for the poor prognosis of these patients. An analysis was conducted on the clinical data of adult PSIS patients who visited the endocrinology department of the First Medical Center of the People's Liberation Army General Hospital from January 2005 to August 2023. Patients were grouped based on their MAFLD and MS status, and the differences in clinical characteristics and risk factors between the groups were analyzed. Machine learning models were used to construct a prediction model for the occurrence of MAFLD in adult PSIS patients and to analyze high-risk predictors. Out of 136 PSIS adult patients, 93.3% were male. The prevalence of MAFLD was 55.5%, and MS was 22.3%. Patients with a history of growth hormone (GH) treatment were less likely to develop MAFLD (P = 0.032). MAFLD patients exhibited higher rates of hypertension, hyperuricemia, obesity, MS, and dyslipidemia. Multiple risk factors may contribute to MS, while no significant link was found between MS and hormone replacement. However, GH non-treatment may serve as the notable predictor of MAFLD in PSIS patients revealed by the Ridge regression model of machine learning model with the highest predictive performance of a mean area under the curve (AUC) of 0.82. The prevalence of MS and MAFLD is high among adult patients with PSIS. Multiple risk factors may contribute to these two diseases, and after constructing a predictive model, we found that MAFLD may be closely linked to the previous lack of GH treatment.

A Pedigree With LHX4 and SOX3 Gene Variants Resulting in Gonadal Dysplasia

Pituitary stalk interruption syndrome is a disease with multiple hormone deficiencies caused by pituitary stalk interruption. Identification of the pathogenic gene variant is helpful for early diagnosis. Early hormone replacement therapy is helpful to improve the prognosis and quality of life of patients. LHX4 (NM_033343.4):c.612G>C (p.Trp204Cys) variant may lead to PSIS.

Pituitary stalk interruption syndrome with coexistent focal cortical dysplasia in a young boy

This case report provides details of the first documented case of pituitary stalk interruption syndrome (PSIS) with coexistent focal cortical dysplasia (FCD) in a young boy. The child's initial presentation was an afebrile, generalised tonic-clonic seizure associated with postictal drowsiness. During his first episode, the physical examination revealed a short, obese child with a micropenis and left cryptorchidism. The neurological examination was normal, suggesting possible endocrine pathology. At that time, laboratory investigations showed a normal complete blood count; electrolyte levels were normal, while the thyroid function test revealed abnormal findings indicative of secondary hypothyroidism. Based on his clinical presentation, physical examination and laboratory investigations, a brain MRI scan was performed, which showed PSIS with diffuse FCD. Subsequently, anterior pituitary gland hormone levels were measured, revealing panhypopituitarism. This discovery is novel in the literature, offers potential new insights into the pathophysiology of PSIS and emphasises the importance of considering structural brain abnormalities in PSIS patients with seizures, thereby opening new avenues for future research on their neurological consequences.

Progress in investigating pituitary stalk lesions: A review

Pituitary stalk lesions are uncommon and are typically identified through pituitary magnetic resonance imaging and screening for causes of diabetes insipidus. Recent literature indicates that pituitary stalk lesions primarily manifest as pituitary stalk interruption syndrome and thickening of the pituitary stalk. The etiology of these lesions is complex and can be divided into major categories: congenital disorders, inflammatory or infectious diseases, and tumors. Therefore, achieving accurate diagnosis, differential diagnosis, and treatment for pituitary stalk lesions is crucial. This article aims to classify pituitary stalk lesions and delve into the latest research on their etiology, pathological mechanisms, clinical manifestations, diagnosis, and treatment of associated diseases.

Pituitary Stalk Interruption Syndrome: A Case and Literature Review

Background/Objective

Pituitary stalk interruption syndrome (PSIS) is a rare congenital disorder that is characterized by a triad including a thin or interrupted pituitary stalk, absent or ectopic posterior lobe, and agenesis or dysgenesis of anterior lobe.PSIS is typically diagnosed in childhood. The objective of this report is to describe a patient with PSIS whose diagnosis was missed until adulthood.

Case Report

A 42-year-old-female presented for evaluation of premature menopause, weight loss, and occasional dizziness. On examination she had short stature and absent secondary sexual features. Laboratory tests were consistent with hypopituitarism with follicle stimulating hormone 0.5 mIU/mL (16.7-113); luteinizing hormone 1.2 mIU/mL (10.8-58.6); prolactin 10.4 ng/mL (2.7-19.6); estradiol 20 pg/mL; cortisol 2 mcg/dL (6.7-22.6); adrenocorticotropic hormone 18 pg/mL (6-50); thyroid stimulating hormone 10.33 uIU/mL (0.28-3.8); free T4 0.41 ng/dL (0.58-1.64); insulin like growth factor-1 -3.7 SD (17 ng/mL) (52-328); and adrenocorticotropic hormone stimulation confirmed secondary adrenal insufficiency. The magnetic resonance imaging of the brain revealed an ectopic posterior pituitary with a partially empty sella, absence of the pituitary stalk, and a small anterior pituitary. The patient was initiated on replacement hormones with improvement in her symptoms.

Discussion

PSIS is a rare condition with uncertain pathogenesis and variable presentation requiring a high index of suspicion and presenting with multiple anterior pituitary hormone deficiencies. Diagnosis is confirmed by a dedicated pituitary magnetic resonance imaging, and treatment is tailored to the hormonal deficiency detected.

Conclusion

This case highlights the importance of early diagnosis of PSIS, which presents with multiple anterior pituitary hormonal deficiencies, but diagnosis can remain elusive unless dedicated brain imaging is performed.

Fgf17: A regulator of the mid/hind brain boundary in mammals

The Fibroblast growth factor (FGFs) family consists of at least 22 members that exert their function by binding and activating fibroblast growth factor receptors (FGFRs). The Fgf8/FgfD subfamily member, Fgf17, is located on human chromosome 8p21.3 and mouse chromosome 14 D2. In humans, FGF17 can be alternatively spliced to produce two isoforms (FGF17a and b) whereas three isoforms are present in mice (Fgf17a, b, and c), however, only Fgf17a and Fgf17b produce functional proteins. Fgf17 is a secreted protein with a cleavable N-terminal signal peptide and contains two binding domains, namely a conserved core region and a heparin binding site. Fgf17 mRNA is expressed in a wide range of different tissues during development, including the rostral patterning centre, midbrain-hindbrain boundary, tailbud mesoderm, olfactory placode, mammary glands, and smooth muscle precursors of major arteries. Given its broad expression pattern during development, it is surprising that adult Fgf17-/- mice displayed a rather mild phenotype; such that mutants only exhibited morphological changes in the frontal cortex and mid/hind brain boundary and changes in certain social behaviours. In humans, FGF17 mutations are implicated in several diseases, including Congenital Hypogonadotropic Hypogonadism and Kallmann Syndrome. FGF17 mutations contribute to CHH/KS in 1.1% of affected individuals, often presenting in conjunction with mutations in other FGF pathway genes like FGFR1 and FLRT3. FGF17 mutations were also identified in patients diagnosed with Dandy-Walker malformation and Pituitary Stalk Interruption Syndrome, however, it remains unclear how FGF17 is implicated in these diseases. Altered FGF17 expression has been observed in several cancers, including prostate cancer, hematopoietic cancers (acute myeloid leukemia and acute lymphoblastic leukemia), glioblastomas, perineural invasion in cervical cancer, and renal cell carcinomas. Furthermore, FGF17 has demonstrated neuroprotective effects, particularly during ischemic stroke, and has been shown to improve cognitive function in ageing mice.

Pulsatile gonadotropin-releasing hormone therapy induces spermatogenesis in pituitary stalk interruption syndrome: A case report and review of the literature

BACKGROUND

Pituitary stalk interruption syndrome (PSIS) is a rare anatomical defect of the pituitary gland falling under the spectrum of holoprosencephaly phenotypes. It is characterized by a deficiency in anterior pituitary hormones, such as growth hormone, gonadotropins, and thyroid hormones. Due to the syndrome's rarity and nonspecific manifestations, there is a lack of standardized treatment strategies. Consequently, early diagnosis through imaging and on-time intervention are crucial for improving patients' outcomes.

CASE SUMMARY

A 30-year-old man presented with absent secondary sexual characteristics and azoospermia. Laboratory evaluation revealed a deficiency in gonadotropins, while thyroid function was mostly within normal ranges. Magnetic resonance imaging of the pituitary gland showed pituitary stalk agenesis, hypoplasia of the anterior pituitary, and ectopic posterior pituitary, leading to the diagnosis of PSIS. Initially, the patient underwent 6 mo of gonadotropin therapy without significant changes in hormone levels and secondary sexual characteristics. Pulsatile gonadotropin-releasing hormone therapy was then administered, resulting in the detection of sperm in the semen analysis within 3 mo. After 6 mo, routine semen tests showed normal semen quality. The couple faced challenges in conceiving due to abstinence and underwent three cycles of artificial insemination, which was unsuccessful. They also attempted in vitro fertilization, but unfortunately, the woman experienced a miscarriage 10 wk after the embryo transfer.

CONCLUSION

Early detection, accurate diagnosis, and timely treatment are crucial in improving the quality of life and fertility of PSIS patients.

Pituitary Stalk Interruption Syndrome with Excessive Height Growth Combined with Congenital Absence of the Uterus and Ovaries: A Rare Case Report and Review of the Literature

Aim

Pituitary stalk interruption syndrome is a relatively rare disease. Patients with this disease usually have different degrees of short stature in adulthood. The purpose of this case report is to highlight a special case of unusually elongated limbs with excessive height growth and congenital absence of uterus and ovary, so as to improve clinicians understanding of the atypical manifestations of pituitary stalk interruption syndrome and provide reference for the clinical diagnosis and treatment of the disease.

Case Presentation

The 30-year-old female patient exhibited disproportionate growth in height, with a significant increase from 140 cm at the age of 16 to 180 cm currently. Physical examination revealed widened bilateral eye fissures, underdeveloped secondary sexual characteristics, and absence of menstruation. The patient 's parents are cousins, belonging to consanguineous marriage. The patient 's hypoglycemia provocation test suggested the lack of growth hormone and cortisol. Gonadorelin provocation test suggested hypogonadism, and thyroid function test showed hypothyroidism. Pituitary MRI plain scan and enhancement suggested pituitary stalk interruption syndrome, and abdominal and urinary color Doppler ultrasound suggested no echo of uterus and bilateral appendages in the pelvic cavity. The karyotype of peripheral blood was 45, X[3] / 46, XX [117]. The patient was diagnosed with pituitary stalk interruption syndrome, congenital uterine and ovarian deficiency, bone overgrowth, hypothyroidism and secondary osteoporosis. During hospitalization, the symptoms were improved and discharged after hormone replacement therapy such as physiological dose of glucocorticoid, estradiol valerate tablets and levothyroxine sodium tablets. Now the patient is still in our hospital endocrinology outpatient follow-up, no special discomfort.

Conclusion

The patient had special clinical manifestations and was clinically confirmed as pituitary stalk interruption syndrome. The patient 's height continues to grow in the absence of growth hormone in the body, and its mechanism remains to be further studied.

Re-analysis of gene mutations found in pituitary stalk interruption syndrome and a new hypothesis on the etiology

Background

Pituitary stalk interruption syndrome (PSIS) is a complex clinical syndrome characterized by varied pituitary hormone deficiencies, leading to severe manifestations across multiple systems. These include lifelong infertility, short stature, mental retardation, and potentially life-threatening pituitary crises if not promptly diagnosed and treated. Despite extensive research, the precise pathogenesis of PSIS remains unclear. Currently, there are two proposed theories regarding the pathogenic mechanisms: the genetic defect theory and the perinatal injury theory.

Methods

We systematically searched English databases (PubMed, Web of Science, Embase) and Chinese databases (CNKI, WanFang Med Online, Sinomed) up to February 24, 2023, to summarize studies on gene sequencing in PSIS patients. Enrichment analyses of reported mutated genes were subsequently performed using the Metascape platform.

Results

Our study included 37 articles. KEGG enrichment analysis revealed mutated genes were enriched in the Notch signaling pathway, Wnt signaling pathway, and Hedgehog signaling pathway. GO enrichment analysis demonstrated mutated genes were enriched in biological processes such as embryonic development, brain development, axon development and guidance, and development of other organs.

Conclusion

Based on our summary and analyses, we propose a new hypothesis: disruptions in normal embryonic development, partially stemming from the genetic background and/or specific gene mutations in individuals, may increase the likelihood of abnormal fetal deliveries, where different degrees of traction during delivery may lead to different levels of pituitary stalk interruption and posterior lobe ectopia. The clinical diversity observed in PSIS patients may result from a combination of genetic background, specific mutations, and variable degrees of traction during delivery.

Obesity, Overweight, and Pituitary Stalk Interruption Syndrome in Children and Young Adults

CONTEXT

Pituitary stalk interruption syndrome (PSIS) is rare in the pediatric population. It combines ectopic posterior pituitary stalk interruption and anterior pituitary hypoplasia with hormonal deficiencies. The phenotype is highly heterogeneous and obesity/overweight seems to be underreported in the literature.

OBJECTIVE

To identify patients with PSIS and obesity or overweight, describe their phenotype, and compare them with patients with PSIS without overweight/obesity.

METHODS

Sixty-nine children and young adults with PSIS in a Toulouse cohort from 1984 to 2019 were studied. We identified 25 obese or overweight patients (OB-OW group), and 44 were nonobese/overweight (NO group). Then the groups were compared.

RESULTS

All cases were sporadic. The sex ratio was 1.6. The main reason for consultation in both groups was growth retardation (61% in OB-OW group, 77% in NO group). History of neonatal hypoglycemia was more common in the OB-OW than in the NO group (57% vs 14%, P = .0008), along with extrapituitary malformations (64% vs 20%, P < 0001). The incidence of caesarean section was higher in the OB-OW group (52%) than in the NO group (23%), although not significant (P = .07).

CONCLUSION

Patients with PSIS who are obese/overweight display interesting phenotypic differences that suggest hypothalamic defects. Studies are needed that include additional information on hormonal levels, particularly regarding oxytocin and ghrelin.

Heterozygous variants in SIX3 and POU1F1 cause pituitary hormone deficiency in mouse and man

Congenital hypopituitarism is a genetically heterogeneous condition that is part of a spectrum disorder that can include holoprosencephaly. Heterozygous mutations in SIX3 cause variable holoprosencephaly in humans and mice. We identified two children with neonatal hypopituitarism and thin pituitary stalk who were doubly heterozygous for rare, likely deleterious variants in the transcription factors SIX3 and POU1F1. We used genetically engineered mice to understand the disease pathophysiology. Pou1f1 loss-of-function heterozygotes are unaffected; Six3 heterozygotes have pituitary gland dysmorphology and incompletely ossified palate; and the Six3+/-; Pou1f1+/dw double heterozygote mice have a pronounced phenotype, including pituitary growth through the palate. The interaction of Pou1f1 and Six3 in mice supports the possibility of digenic pituitary disease in children. Disruption of Six3 expression in the oral ectoderm completely ablated anterior pituitary development, and deletion of Six3 in the neural ectoderm blocked the development of the pituitary stalk and both anterior and posterior pituitary lobes. Six3 is required in both oral and neural ectodermal tissues for the activation of signaling pathways and transcription factors necessary for pituitary cell fate. These studies clarify the mechanism of SIX3 action in pituitary development and provide support for a digenic basis for hypopituitarism.

Copy number variation in pituitary stalk interruption syndrome: A large case series of sporadic non-syndromic patients and literature review

Abnormal hypothalamic/posterior pituitary development appears to be a major determinant of pituitary stalk interruption syndrome (PSIS). The observation of familial cases and associated congenital abnormalities suggests a genetic basis. Single-gene mutations explain less than 5% of the cases, and whole exome sequencing has shown heterogeneous results. The present study aimed to assess copy number variation (CNV) using array-based comparative genomic hybridization (aCGH) in patients with non-syndromic PSIS and comprehensively review data from the literature on CNV analysis in congenital hypopituitarism (CH) patients. Twenty-one patients with sporadic CH from our outpatient clinics presented with ectopic posterior pituitary (EPP) and no central nervous system abnormalities on magnetic resonance image (MRI) or any other malformations on physical examination at presentation were enrolled in the study. aCGH using a whole-genome customized 400K oligonucleotide platform was performed in our patients. For the literature review, we searched for case reports of patients with CH and CNV detected by either karyotype or aCGH reported in PubMed up to November 2021. Thirty-five distinct rare CNVs were observed in 18 patients (86%) and two of them (6%) were classified as pathogenic: one deletion of 1.8 Mb in chromosome 17 (17q12) and one deletion of 15 Mb in chromosome 18 (18p11.32p11.21), each one in a distinct patient. In the literature review, 67 pathogenic CNVs were published in 83 patients with CH, including the present study. Most of these patients had EPP (78% out of the 45 evaluated by sellar MRI) and were syndromic (70%). The most frequently affected chromosomes were X, 18, 20 and 1. Our study has found that CNV can be a mechanism of genetic abnormality in non-syndromic patients with CH and EPP. In future studies, one or more genes in those CNVs, both pathogenic and variant of uncertain significance, may be considered as good candidate genes.

Normal or elevated prolactin is a good indicator to show pituitary stalk interruption syndrome in patients with multiple pituitary hormone deficiency

OBJECTIVES

To determine the importance of serum prolactin (PRL) in the detection of pituitary stalk interruption syndrome (PSIS) in children with multiple pituitary hormone deficiency (MPHD). We hypothesized that PRL elevation might be a diagnostic indicator of pituitary stalk pathologies.

METHODS

Clinical, radiological, and laboratory features of the 50 cases of MPHD were studied.

RESULTS

The median age at presentation of the 50 cases (52%, n=26 were female) was 6.61 (0.02-18.9) years. PSIS was detected in 60% (n=30), pituitary hypoplasia in 32% (n=16), partial empty sella in 6% (n=3), and only 2% (n=1) was reported as normal. Out of 50 patients, 21.3% (n=10) were hypoprolactinemic, 44.7% (n=19) were normoprolactinemic, and 34% (n=16) were hyperprolactinemic. The median PRL value was 27.85 (4.21-130) ng/mL in patients with PSIS and 5.57 (0-41.8) ng/mL in patients without PSIS. Additional hormone deficiencies, especially ACTH and LH were detected in follow-up.

CONCLUSIONS

Patients with normal or high prolactin levels deserve special attention regarding the possibility of PSIS. Furthermore, we emphasize the importance of regular follow-up and monitoring for multiple pituitary hormone deficiencies in all patients with a single pituitary hormone deficiency.

Diagnostic value of magnetic resonance imaging ectopic posterior pituitary hyperintense signal in pituitary macroadenoma

Objective

When the lesions in the sellar region are large, they can involve both the inside and outside the sella, which brings challenges to the differential diagnosis of pituitary macroadenoma and lesions other than macroadenoma. Therefore, this study explored the diagnostic value of an ectopic posterior pituitary hyperintense signal (EPPHS) in pituitary macroadenoma and its possible causes.

Methods

The clinical and imaging data of 131 patients with sellar tumors or tumor-like lesions involving both intrasellar and extrasellar regions in the Affiliated Hospital of Guizhou Medical University from February 2011 to December 2021 were analyzed retrospectively. The diagnostic value of EPPHS in pituitary macroadenoma was analyzed. The differences in clinical and imaging indexes between the EPPHS-positive group and the EPPHS-negative group were compared.

Results

These 131 cases of sellar tumors or tumor-like lesions involving both intrasellar and extrasellar regions included 91 cases of pituitary macroadenoma and 40 cases of lesions other than macroadenoma. The receiver operator characteristic (ROC) curve analysis suggested that EPPHS had a diagnostic value in diagnosing pituitary macroadenoma [area under the curve (AUC) = 0.857, P = 0.0001]. Compared with the EPPHS negative group, the median prolactin level in the EPPHS positive group was significantly higher (P &lt; 0.05). Through ROC curve analysis, prolactin value was found to be of diagnostic value for EPPHS (AUC = 0.612, P = 0.0312).

Conclusion

In sellar tumors or tumor-like lesions involving both intrasellar and extrasellar regions, the appearance of EPPHS is helpful in the diagnosis of pituitary macroadenoma. The formation of EPPHS may be related to injuries to the pituitary stalk.

Whole exome sequencing in patients with ectopic posterior pituitary

Context

Ectopic posterior pituitary (EPP), a condition in which the posterior pituitary gland is displaced due to defective neuronal migration, is frequently associated with hypopituitarism. Genetic variants play a role, but many cases remain unexplained.

Objective

A large EPP cohort was studied to explore the importance of genetic variants and how they correlate with clinical findings.

Methods

Whole exome sequencing was performed on a discovery sample of 27 cases to identify rare variants. The variants that met the criteria for rarity and biological relevance, or that were previously associated with EPP (ROBO1 and HESX1), were then resequenced in the 27 cases plus a replication sample of 51 cases.

Results

We identified 16 different variants in 12 genes in 15 of the 78 cases (19.2%). Complete anterior pituitary deficiency was twice as common in cases with variants of interest compared to cases without variants (9/15; 60% vs. 19/63; 30.1%, respectively; Z test; p=0.06). Breech presentation was more frequent in the variant positive group (5/15 vs. 1/63; Z test; p= 0.003). Four cases had variants in ROBO1 and one in HESX1, genes previously associated with EPP. The ROBO1 p.S18* variant has not been reported previously; ROBO1 p.Q1227H has not been associated with EPP previously.

Conclusions

EPP cases with variants of interest identified in this study were more likely to present with severe clinical disease. Several variants were identified in genes not previously associated with EPP. Our findings confirm that EPP is a multigenic disorder. Future studies are needed to identify additional genes.

Seminal plasma metabolomics and lipidomics profiling to identify signatures of pituitary stalk interruption syndrome

Background

Pituitary stalk interruption syndrome (PSIS) is a rare disease caused by congenital pituitary anatomical defects. The underlying mechanisms remain unclear, and the diagnosis is difficult. Here, integrated metabolomics and lipidomics profiling were conducted to study the pathogenesis of PSIS.

Methods

Twenty-one patients with PSIS (BD group) and twenty-three healthy controls (HC group) were enrolled. Basal information and seminal plasma samples were collected. Untargeted metabolomics and lipidomics analyses were performed using ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS).

Results

The metabolomics and lipidomics profiles of patients with PSIS changed. The prolactin signaling pathway and biosynthesis of amino acids were the main differentially modified metabolic pathways. The main differentially modified metabolites were triacylglycerols (TGs), phosphatidylethanolamine (PE), sphingomyelin (SM), ceramide (Cer) and phosphatidylcholines (PCs). Pregnenolones and L-saccharopine could achieve a diagnosis of PSIS.

Conclusions

Pregnenolones and L-saccharopine are potential biomarkers for a PSIS diagnosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02408-4.

Evaluations of exercise intolerance with cardiopulmonary exercise tests in an 18-year-old adolescent with pituitary stalk interruption syndrome: a case report

BACKGROUND

Pituitary stalk interruption syndrome (PSIS) is a rare disease associated with different level of anterior pituitary hormone deficiency resulting with a variety of clinical manifestations which could limit exercise capacity. Cardiopulmonary exercise test (CPET) is valuable in differential diagnosis of exercise intolerance and exercise prescription.

CASE PRESENTATION

An 18-year-old male adolescent was diagnosed with PSIS at 4 years old, had undergone growth hormone supplement until puberty, and was referred to rehabilitation department due to exercise intolerance. We arranged pulmonary function test (PFT) and CPET to clarify the cause of limited capacity. The test result provided evidence of moderate functional impairment (54% of predicted maximal oxygen uptake) mainly affected by physical unfitness without significant cardiovascular or pulmonary limitations.

CONCLUSION

CPET serves as a valuable tool for diagnostic purpose. Aerobic and resistance exercise training for the patient should be conducted promptly for better prognosis but under safe circumstances, with criteria which could be provided by CPET results.

Efficacy of Pulsatile Gonadotropin-Releasing Hormone Therapy in Male Patients: Comparison between Pituitary Stalk Interruption Syndrome and Congenital Hypogonadotropic Hypogonadism

OBJECTIVE

Pulsatile gonadotropin-releasing hormone (GnRH), widely used to induce spermatogenesis in congenital hypogonadotropic hypogonadism (CHH) patients, can restore the pituitary-testis axis function in males with pituitary stalk interruption syndrome (PSIS). This retrospective study aimed to compare the long-term efficacy of pulsatile GnRH therapy between PSIS and CHH.

METHODS

Patients of PSIS (n=25) or CHH (n=64) who received pulsatile GnRH therapy ≥ 3 months were analyzed in this retrospective study. The rate of successful spermatogenesis, the median time to achieve spermatogenesis, serum gonadotropins, total testosterone (TT), and testicular size were compared.

RESULTS

Baseline characteristics were comparable except for the lower basal testosterone, triptorelin stimulated peak luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in patients with PSIS. Within similar treatment durations, significantly higher GnRH dose (p < 0.001) but lower increase in LH [2.82 (1.4, 4.55) vs. 5.89 (3.88, 8.02) IU/L, p < 0.001], TT [0.38 (0, 1.34) vs. 2.34 (1.34, 3.66) ng/mL, p < 0.001], and testicular volume (5.3 ± 4.5 vs. 8.8 ± 4.8 mL, p < 0.05) were observed in PSIS. However, spermatogenesis rate (52.0% vs. 70.3%, p > 0.05), median time of sperm appearance (14 vs. 11 months, p > 0.05), sperm concentration and progressive motility were comparable. Basal testicular volume (HR 1.13, 95% CI 1.01-1.27) and peak LH levels (HR 1.11, 95% CI 1.0-1.23) were predictors for early sperm appearance.

CONCLUSIONS

Pulsatile GnRH therapy can improve gonad function and induce spermatogenesis in male PSIS patients, however, its efficacy may be inferior to that in CHH.

Idiopathic combined adrenocorticotropin and growth hormone deficiency mimicking chronic fatigue syndrome

A 42-year-old man who had suffered from severe fatigue for 5 years was diagnosed as having chronic fatigue syndrome (CFS) and fibromyalgia. Endocrinological workup using combined anterior pituitary function tests showed that the patient had adrenocorticotropin hormone (ACTH) deficiency, with a normal pituitary MRI. Treatment with a physiologic dose of oral hydrocortisone replacement physically ameliorated his general fatigue. A secondary workup using a growth hormone-releasing peptide-2 test revealed that he also had growth hormone (GH) deficiency, and GH replacement therapy was started. His muscle pain and depression were improved by the therapy. Here, we present a rare case of combined deficiency of ACTH and GH in a middle-aged man with severe general fatigue. This case report aims to raise awareness of combined deficiency of ACTH and GH as a differential diagnosis of CFS and its mimics.

CDON gene contributes to pituitary stalk interruption syndrome associated with unilateral facial and abducens nerve palsy

The relationship between congenital defects of the brain and facial anomalies was proven. The Hedgehog signaling pathway plays a fundamental role in normal craniofacial development in humans. Mutations in the sonic hedgehog (SHH) signaling gene CDON have been recently reported in patients with holoprosencephaly and with pituitary stalk interruption syndrome (PSIS). This study’s aim was an elucidation of an 18-year-old patient presenting PSIS, multiple pituitary hormone deficiency, and congenital unilateral facial and abducens nerve palsy. Additionally, bilateral sensorineural hearing loss, dominating at the right site, was diagnosed. From the second year of life, growth deceleration was observed, and from the age of eight, anterior pituitary hormone deficiencies were gradually confirmed and substituted. At the MRI, characteristic triad for PSIS (anterior pituitary hypoplasia, interrupted pituitary stalk and ectopic posterior lobe) was diagnosed. We performed a comprehensive genomic screening, including microarrays for structural rearrangements and whole-exome sequencing for a monogenic defect. A novel heterozygous missense variant in the CDON gene (c.1814G > T; p.Gly605Val) was identified. The variant was inherited from the mother, who, besides short stature, did not show any disease symptoms. The variant was absent in control databases and 100 healthy subjects originating from the same population. We report a novel variant in the CDON gene associated with PSIS and congenital cranial nerve palsy. The variant revealed autosomal dominant inheritance with incomplete penetrance in concordance with previous studies reporting CDON defects.

Hypoglycemia and jaundice in newborns with pituitary stalk interruption syndrome

Pituitary stalk interruption syndrome (PSIS) is a rare disease associated with either isolated growth hormone deficiency (GHD) or combined pituitary hormone deficiency (CPHD). In older children and adults, most patients experience short stature or hypogonadism. Neonatal PSIS is extremely rare and is difficult to recognize due to absence of dwarfism. However, when this condition occurs in newborns, it is often life-threatening. Here, we collected patients with neonatal PSIS to clarify its characteristics to improve its early diagnosis.The patients included in this study were treated at the pediatric endocrine department of Shandong Provincial Hospital from January 2017 to July 2020. We obtained the clinical characteristics, endocrine hormone levels, pituitary magnetic resonance imaging (MRI) and further genetic data for all the patients. Hormone therapy was first given at the time of diagnosis, and the patients received regular follow-up.Three neonatal patients were identified in our clinic. The characteristics of these patients included hypoglycemia and jaundice, as well as CPHD, which included features such as micropenis and hypothyroidism. Genetic etiology was still hard to discover. All the patients responded well to alternative therapy, and the longest follow-up period was 3 years. Regular replacement ensures good prognosis.Sustained hypoglycemia and jaundice in newborns, indicate the presentation of PSIS. Early recognition is of great importance to avoid a life-threatening crisis.

Neurobiology of puberty and its disorders

Puberty, which in humans is considered to include both gonadarche and adrenarche, is the period of becoming capable of reproducing sexually and is recognized by maturation of the gonads and development of secondary sex characteristics. Gonadarche referring to growth and maturation of the gonads is fundamental to puberty since it encompasses increased gonadal steroid secretion and initiation of gametogenesis resulting from enhanced pituitary gonadotropin secretion, triggered in turn by robust pulsatile GnRH release from the hypothalamus. This chapter reviews the development of GnRH pulsatility from before birth until the onset of puberty. In humans, GnRH pulse generation is restrained during childhood and juvenile development. This prepubertal hiatus in hypothalamic activity is considered to result from a neurobiological brake imposed upon the GnRH pulse generator resident in the infundibular nucleus. Reactivation of the GnRH pulse generator initiates pubertal development. Current understanding of the genetics and physiology of the brake will be discussed, as will hypotheses proposed to account for timing the resurgence in pulsatile GnRH and initiation of puberty. The chapter ends with a discussion of disorders associated with precocious or delayed puberty with a focus on those with etiologies attributed to aberrant GnRH neuron anatomy or function. A pediatric approach to patients with pubertal disorders is provided and contemporary treatments for both precocious and delayed puberty outlined.

Pituitary stalk interruption syndrome

Pituitary stalk interruption syndrome (PSIS) is a distinct developmental defect of the pituitary gland identified by magnetic resonance imaging and characterized by a thin, interrupted, attenuated or absent pituitary stalk, hypoplasia or aplasia of the adenohypophysis, and an ectopic posterior pituitary. The precise etiology of PSIS still remains elusive or incompletely confirmed in most cases. Adverse perinatal events, including breech delivery and hypoxia, were initially proposed as the underlying mechanism affecting the hypothalamic-pituitary axis. Nevertheless, recent findings have uncovered a wide variety of PSIS-associated molecular defects in genes involved in pituitary development, holoprosencephaly (HPE), neural development, and other important cellular processes such as cilia function. The application of whole exome sequencing (WES) in relatively large cohorts has identified an expanded pool of potential candidate genes, mostly related to the Wnt, Notch, and sonic hedgehog signaling pathways that regulate pituitary growth and development during embryogenesis. Importantly, WES has revealed coexisting pathogenic variants in a significant number of patients; therefore, pointing to a multigenic origin and inheritance pattern of PSIS. The disorder is characterized by inter- and intrafamilial variability and incomplete or variable penetrance. Overall, PSIS is currently viewed as a mild form of an expanded HPE spectrum. The wide and complex clinical manifestations include evolving pituitary hormone deficiencies (with variable timing of onset and progression) and extrapituitary malformations. Severe and life-threatening symptomatology is observed in a subset of patients with complete pituitary hormone deficiency during the neonatal period. Nevertheless, most patients are referred later in childhood for growth retardation. Prompt and appropriate hormone substitution therapy constitutes the cornerstone of treatment. Further studies are needed to uncover the etiopathogenesis of PSIS.

Desmopressin Suppresses Gonadotropin-Induced Spermatogenesis in Patients With Pituitary Stalk Interruption Syndrome: A Retrospective, Single-Center Cohort Study

OBJECTIVE

To explore the influence of desmopressin on gonadotropin-induced spermatogenesis in patients with pituitary stalk interruption syndrome (PSIS).

METHODS

A single-center retrospective cohort study was conducted. All patients with PSIS had both gonadotropin and growth hormone (GH) deficiency. Patients were divided into desmopressin and nondesmopressin groups. The desmopressin and nondesmopressin groups were defined by the presence or absence of central diabetes insipidus, which determined whether the patient received desmopressin or not.

RESULTS

The average age of gonadotropin therapy was 24.3 and 26.1 in the desmopressin and nondesmopressin groups, respectively. The rate of successful spermatogenesis in the 2 groups was 31.58% and 77.27%, respectively. The period for first sperm appearance was 13.62 ± 5.95 and 13.48 ± 6.69 months, respectively. A multivariable Cox proportional hazards model found that the adjusted hazard ratio for desmopressin was 0.260, indicating a "possible" detrimental effect of desmopressin on spermatogenesis. Central diabetes insipidus would be expected to show a similar detrimental effect. The spermatogenesis rate decreased with increased dosage of desmopressin. In the nondesmopressin group, the rate of spermatogenesis was similar between the GH group and the non-GH subgroup. The GH group had higher sperm count and concentration than the non-GH group.

CONCLUSION

A minority of patients with PSIS had mild diabetes insipidus and received desmopressin therapy. The spermatogenesis rate decreased with increasing desmopressin dosage. In addition, GH supplementation did not affect the spermatogenesis rate.

Pituitary stalk interruption syndrome: A rare case report and literature review

RATIONALE

Pituitary stalk interruption syndrome (PSIS) is a congenital pituitary anatomical defect. It is characterized by the triad of thin or interrupted pituitary stalk, absent or ectopic posterior lobe, and hypoplastic or aplastic anterior lobe. Moreover, this condition is considered rare.

PATIENT CONCERNS

A 23-year-old male patient presented with a history of short stature and hypogonadism. Laboratory assessment revealed low thyroxine, cortisol, and adrenocorticotropic hormone levels, which are consistent with adrenal insufficiency without hypoglycemia. The insulin-induced hypoglycemia tolerance test finding indicated growth hormone (GH) deficiency. Moreover, magnetic resonance imaging revealed an interrupted pituitary stalk, ectopic posterior pituitary, and hypoplastic anterior pituitary. This triad of symptoms was indicative of PSIS.

DIAGNOSIS

INTERVENTIONS:: The patient was deficient in adrenaline, thyroxine, gonadal steroid, and GH. Thus, glucocorticoid replacement therapy was initiated, followed by euthyrox, androgen, and human chorionic gonadotropin treatment. Calcium tablets, calcitriol, and alendronate sodium were used for the management of osteoporosis. The patient was 164 cm tall, and his bone age was approximately 15 years old. However, owing to a poor economic condition, the family did not proceed with GH therapy.

OUTCOMES

The patient did not present with adrenal or hypothyroidism crisis after receiving poly-hormonal replacement therapy. His secondary sexual characteristics began to develop. However, owing to a short treatment window period, the patient could not receive the required treatment. Hence, whether the patient would have a normal fertility function needs to be confirmed.

LESSONS

PSIS is a rare disease with various clinical characteristics. During the neonatal period and infancy, the signs and symptoms of PSIS are often not evident. Therefore, diagnosis is delayed. The early detection of hormone deficiency and treatment initiation can affect both the quality of life and the prognosis of patients with PSIS. Thus, the diagnosis and treatment of this disease must be improved to help patients achieve a better quality of life and to prevent reproductive health problems.

Pituitary stalk interruption syndrome and liver changes: From clinical features to mechanisms

Pituitary stalk interruption syndrome (PSIS) is a rare congenital abnormality characterized by thinning or disappearance of the pituitary stalk, hypoplasia of the anterior pituitary and an ectopic posterior pituitary. Although the etiology of PSIS is still unclear, gene changes and perinatal adverse events such as breech delivery may play important roles in the pathogenesis of PSIS. PSIS can cause multiple hormone deficiencies, such as growth hormone, which then cause a series of changes in the human body. On the one hand, hormone changes affect growth and development, and on the other hand, they could affect human metabolism and subsequently the liver resulting in nonalcoholic fatty liver disease (NAFLD). Under the synergistic effect of multiple mechanisms, the progression of NAFLD caused by PSIS is faster than that due to other causes. Therefore, in addition to early identification of PSIS, timely hormone replacement therapy and monitoring of relevant hormone levels, clinicians should routinely assess the liver function while managing PSIS.

Identification of novel candidate pathogenic genes in pituitary stalk interruption syndrome by whole-exome sequencing

Pituitary stalk interruption syndrome (PSIS) is a type of congenital malformation of the anterior pituitary, which leads to isolated growth hormone deficiency or multiple hypothalamic-pituitary deficiencies. Many genetic factors have been explored, but they only account for a minority of the genetic aetiology. To identify novel PSIS pathogenic genes, we conducted whole-exome sequencing with 59 sporadic PSIS patients, followed by filtering gene panels involved in pituitary development, holoprosencephaly and midline abnormality. A total of 81 heterozygous variants, distributed among 59 genes, were identified in 50 patients, with 31 patients carrying polygenic variants. Fourteen of the 59 pathogenic genes clustered to the Hedgehog pathway. Of them, PTCH1 and PTCH2, inhibitors of Hedgehog signalling, showed the most frequent heterozygous mutations (22%, seven missense and one frameshift mutations were identified in 13 patients). Moreover, five novel heterozygous null variants in genes including PTCH2 (p.S391fs, combined with p.L104P), Hedgehog acyltransferase (p.R280X, de novo), MAPK3 (p.H50fs), EGR4 (p.G22fs, combined with LHX4 p.S263N) and SPG11 (p.Q1624X), which lead to truncated proteins, were identified. In conclusion, genetic mutations in the Hedgehog signalling pathway might underlie the complex polygenic background of PSIS, and the findings of our study could extend the understanding of PSIS pathogenic genes.

NBPF9 Gene May Be Involved in Congenital Hypopituitarism: A Whole-Genome Study of a Boy with Pituitary Stalk Interruption Syndrome and His Family

Pituitary stalk interruption syndrome (PSIS) is a rare congenital defect manifesting as various degrees of anterior pituitary hormone deficiency. Scattered familial cases have been found, revealing some genetic variants. However, most of the previous research studies involved an affected sibling, and the gene spectra of the patients' entire family have rarely been reported. We conducted a study of a family consisting of a PSIS patient with his unaffected sibling and healthy parents of Han Chinese background using whole-genome sequencing. Bioinformatic analysis was carried out, and mutations related to PSIS, single-nucleotide variants (SNVs), insertion-deletion (InDELs), and structural variations (SVs) in all the four samples were filtered. After Sanger sequencing, we confirmed the variants obtained and selected three candidate genes for functional verification. The gene variations in this boy with PSIS and his lineal relatives are reported herein; de novo sequencing revealed that the NBPF9 gene may be involved in the pathogenesis of PSIS.

Osteogenesis Imperfecta Due to Combined Heterozygous Mutations in Both COL1A1 and COL1A2, Coexisting With Pituitary Stalk Interruption Syndrome

Osteogenesis imperfecta (OI) is a hereditary connective tissue disorder, characterized by reduced bone content, fractures and skeletal malformation due to abnormal synthesis or dysfunction of type I collagen protein. Pituitary stalk interruption syndrome (PSIS) is usually associated with environmental and hereditary factors. Here, we report a rare case of OI and PSIS co-occurrence. A 19-year-old male patient sought treatment for growth delay and absent secondary sexual characteristics. Hormone measurements indicated the presence of hypopituitarism (secondary hypothyroidism, growth hormone deficiency, ACTH-cortisol hormone deficiency, hypogonadotropic hypogonadism). Pituitary magnetic resonance imaging indicated reduced morphology of the anterior lobe, absence of the pituitary stalk, and ectopic displacement of the posterior lobe to the infundibulum, supporting a diagnosis of PSIS. In addition, the patient, his monozygotic twin brother (no evidence of PSIS), and their mother all presented blue sclera and susceptibility to bone fractures before adulthood. Next-generation sequencing demonstrated that the family had compound heterozygous mutations in COL1A1 and COL1A2, with no known mutations related to PSIS, pituitary hormone deficiency (PHD), or holoprosencephaly (HPE). The mother experienced breech and natural delivery of the patient and his brother, respectively. Thus, we deduced that the patient's PSIS might have resulted from breech delivery. Although we cannot exclude the possibility that the proband might have an undetected genetic abnormality causing PSIS or increasing his susceptibility to damage to the hypothalamic-pituitary region due to the limitation of exome sequencing, this rare case suggests that breech delivery in the newborn with OI might be related to PSIS.

Single center study of 53 consecutive patients with pituitary stalk lesions

BACKGROUND

The etiological spectrum of pituitary stalk lesions (PSL) is wide and yet specific compared to the other diseases of the sellar and suprasellar region. Because of the pituitary stalk's (PS) critical location and role, biopsies of these lesions are rarely performed, and their underlying pathology is often a conundrum for clinicians. A pituitary MRI in association with a clinical context can facilitate their diagnosis.

AIM

To present the various causes of PSL-their clinical, hormonal, histopathological, and MRI characteristics in order to gain better insight into this pathology.

METHOD

A retrospective observational study consisting of 53 consecutive patients with PSL of the mean age 32 ± 4.2 years (range 6-67), conducted at the Department for Neuroendocrinology, Clinical Center of Serbia 2010-2018.

RESULTS

Congenital malformations were the most common cause of PSL in 25 of 53 patients (47.1%), followed by inflammatory (9/53; 16.9%) and neoplastic lesions (9/53; 16.9%). The exact cause of PSL was established in 31 (58.4%) patients, of whom 23 were with congenital PS abnormalities and 8 with histopathology of PSL (7 neoplastic and 1 Langerhans Cell Hystiocytosis). A probable diagnosis of PSL was stated in 12 patients (22.6%): 6 with lymphocytic panhypophysitis, while Rathke cleft cyst, tuberculosis, dissemination of malignancy in PS were each diagnosed in 2 patients. In 10 patients (18.8%), the etiology of PSL remained unknown.

CONCLUSION

Due to the inability of establishing an exact diagnosis, the management and prognosis of PSL are difficult in many patients. By presenting a wide array of causes implicated in this condition, we believe that our study can aid clinicians in the challenging cases of this pathology.

[Ectopia of the pituitary]

The adenohypophysis has a large intrasellar part and two small parts at the pituitary stalk and the pharynx. Near this extrasellar pituitary tissue, and also in sinus sphenoidalis and sinus cavernosus, ectopic pituitary adenomas can develop. They are indistinguishable in structure and function from usual intrasellar adenomas. The neurohypophysis can show dystopias within complex malformations. In so-called pituitary stalk interruption syndrome, a real ectopia of the neurohypophysis is found at the eminentia mediana of the hypothalamus. Ectopic tissue in the pituitary is extremely rare: foci of ganglionic cells were found in the neurohypophysis and adrenocortical tissue in the adenohypophysis. Focal squamous epithelia in the anterior pituitary are a common finding but they are rather metaplastic from parenchymal cells than ectopic tissue. Small foci of ectopic salivary gland tissue are not rare in the intermediate zone.

MRI of ectopic posterior pituitary gland with dysgenesis of pituitary stalk in a patient with hypogonadotropic hypogonadism

The ectopic posterior pituitary is a rare condition which is characterized by the ectopic location of posterior lobe of pituitary, pituitary stalk abnormalities, and associated clinical manifestations of anterior lobe related growth hormone dysfunction or less commonly multiple anterior pituitary dysfunctions. We present a rare case of posterior ectopic pituitary and pituitary stalk hypoplasia with isolated hypogonadotropic hypogonadism in a 36-year-old female patient.

The Missing Link: A Case of Absent Pituitary Infundibulum and Ectopic Neurohypophysis in a Pediatric Patient with Heterotaxy Syndrome

We report a case of absent pituitary infundibulum and ectopic neurohypophysis in a 4-year-old patient presenting clinically with hypopituitarism as well as heterotaxy syndrome complicated by global developmental delay and growth retardation. The clinical and laboratory workup of our patient suggested underlying hypopituitarism related to either congenital or acquired pathology, necessitating MRI to distinguish between them. We explain the various structural causes of hypopituitarism and detail how to predict the MRI findings and treatment, based on a fundamental understanding of the anatomy and pathophysiology of the hypothalamic pituitary axis and distinguishing anterior versus posterior pituitary hormone derangements. We also discuss two important theories widely acknowledged in the literature to explain congenital hypopituitarism: 1. Head trauma typically during birth resulting in a stretch injury to the infundibulum. 2. Congenital fetal maldevelopment of midline structures.

Delayed diagnosis of pituitary stalk interruption syndrome with severe recurrent hyponatremia caused by adrenal insufficiency

Pituitary stalk interruption syndrome (PSIS) involves the occurrence of a thin or absent pituitary stalk, hypoplasia of the adenohypophysis, and ectopic neurohypophysis. Diagnosis is confirmed using magnetic resonance imaging. Patients with PSIS have a variable degree of pituitary hormone deficiency and a wide spectrum of clinical manifestations. The clinical course of the disease in our patient is similar to that of a syndrome of inappropriate antidiuretic hormone secretion. This is thought to be caused by failure in the suppression of vasopressin secretion due to hypocortisolism. To the best of our knowledge, there is no case report of a patient with PSIS presenting with hyponatremia as the first symptom in Korean children. Herein, we report a patient with PSIS presenting severe recurrent hyponatremia as the first symptom, during adolescence and explain the pathophysiology of hyponatremia with secondary adrenal insufficiency.

Multi-genic pattern found in rare type of hypopituitarism: a whole-exome sequencing study of Han Chinese with pituitary stalk interruption syndrome

Pituitary stalk interruption syndrome (PSIS) is a rare type of hypopituitarism manifesting various degrees of pituitary hormone deficiency. Although mutations have been identified in some familial cases, the underpinning mechanisms of sporadic patients with PSIS who are in a vast majority remain elusive, necessitating a comprehensive study using systemic approaches. We postulate that other genetic mechanisms may be responsible for the sporadic PSIS. To test this hypothesis, we conducted a study in 24 patients with PSIS of Han Chinese with no family history using whole‐exome sequencing (WES) and bioinformatic analysis. We identified a group of heterozygous mutations in 92% (22 of 24) of the patients, and these genes are mostly associated with Notch, Shh, Wnt signalling pathways. Importantly, 83% (20 of 24) of the patients had more than one mutation in those pathways suggesting synergy of compound mutations underpin the pathogenesis of sporadic PSIS.

Digenic Inheritance of PROKR2 and WDR11 Mutations in Pituitary Stalk Interruption Syndrome

CONTEXT

Pituitary stalk interruption syndrome (PSIS, ORPHA95496) is a congenital defect of the pituitary gland characterized by the triad of a very thin/interrupted pituitary stalk, an ectopic (or absent) posterior pituitary gland, and hypoplasia or aplasia of the anterior pituitary gland. Complex genetic patterns of inheritance of this disorder are increasingly recognized.

OBJECTIVE

The objective of this study was to identify a genetic cause of PSIS in an affected child.

METHODS

Whole exome sequencing (WES) was performed by using standard techniques, with prioritized genetic variants confirmed via Sanger sequencing. To investigate the effects of one candidate variant on mutant WDR11 function, Western blotting and coimmunofluorescence were used to assess binding capacity, and leptomycin B exposure along with immunofluorescence was used to assess nuclear localization.

RESULTS

We describe a child who presented in infancy with combined pituitary hormone deficiencies and whose brain imaging demonstrated a small anterior pituitary, ectopic posterior pituitary, and a thin, interrupted stalk. WES demonstrated heterozygous missense mutations in two genes required for pituitary development, a known loss-of-function mutation in PROKR2 (c.253C>T;p.R85C) inherited from an unaffected mother, and a WDR11 (c.1306A>G;p.I436V) mutation inherited from an unaffected father. Mutant WDR11 loses its capacity to bind to its functional partner, EMX1, and to localize to the nucleus.

CONCLUSIONS

WES in a child with PSIS and his unaffected family implicates a digenic mechanism of inheritance. In cases of hypopituitarism in which there is incomplete segregation of a monogenic genotype with the phenotype, the possibility that a second genetic locus is involved should be considered.