Small pituitary size in children with Fanconi anemia

Fanconi anemia and dyskeratosis congenita/telomere biology disorders: Two inherited bone marrow failure syndromes with genomic instability

Inherited bone marrow failure syndromes (IBMFS) are a complex and heterogeneous group of genetic diseases. To date, at least 13 IBMFS have been characterized. Their pathophysiology is associated with germline pathogenic variants in genes that affect hematopoiesis. A couple of these diseases also have genomic instability, Fanconi anemia due to DNA damage repair deficiency and dyskeratosis congenita/telomere biology disorders as a result of an alteration in telomere maintenance. Patients can have extramedullary manifestations, including cancer and functional or structural physical abnormalities. Furthermore, the phenotypic spectrum varies from cryptic features to patients with significantly evident manifestations. These diseases require a high index of suspicion and should be considered in any patient with abnormal hematopoiesis, even if extramedullary manifestations are not evident. This review describes the disrupted cellular processes that lead to the affected maintenance of the genome structure, contrasting the dysmorphological and oncological phenotypes of Fanconi anemia and dyskeratosis congenita/telomere biology disorders. Through a dysmorphological analysis, we describe the phenotypic features that allow to make the differential diagnosis and the early identification of patients, even before the onset of hematological or oncological manifestations. From the oncological perspective, we analyzed the spectrum and risks of cancers in patients and carriers.

Central nervous system lesions in Fanconi anemia: Experience from a research center for Fanconi anemia patients

BACKGROUND

Brain atrophy, abnormal pituitary morphology, corpus callosum, and posterior fossa abnormalities have been described in patients with Fanconi anemia (FA). We aimed to provide an overview of cranial neuroimaging findings and to evaluate the clinical implications in FA patients.

PROCEDURE

Cranial magnetic resonance imaging (MRI) studies of 34 patients with FA were retrospectively evaluated, and patients' clinical data were correlated with the imaging findings.

RESULTS

The patients' median age was 17.6 (range, 3.9-28) years. At least one pathological brain imaging finding was demonstrated in 22 (65%) patients. These findings included corpus callosum abnormalities and other related supratentorial malformations in nine, pituitary abnormalities in eight, craniovertebral junction and posterior fossa abnormalities in eight, vascular lesions in six, and intracerebral calcifications in two patients. Among the 22 patients who had abnormal cranial MRI findings, six (27%) had mild to moderate intellectual disability (ID), three (14%) had epilepsy, one (5%) had mild hearing loss, and one patient (5%) had hemiplegia. Among these 34 patients, 14 (41%) were transfusion dependent. There was no significant difference between patients with congenital and acquired neuroimaging findings and patients with normal neuroimaging regarding transfusion dependency.

CONCLUSIONS

Acquired abnormalities in brain tissue, such as white matter intensity changes, white matter T2 hyperintense discrete foci, or infarcts along with congenital abnormalities, were identified in this study. Variable abnormal brain imaging findings in FA patients, although some were not associated with clinical neurological manifestations, suggest that brain imaging could be part of screening in FA.

Peptide Hormone Regulation of DNA Damage Responses

DNA damage response (DDR) and DNA repair pathways determine neoplastic cell transformation and therapeutic responses, as well as the aging process. Altered DDR functioning results in accumulation of unrepaired DNA damage, increased frequency of tumorigenic mutations, and premature aging. Recent evidence suggests that polypeptide hormones play a role in modulating DDR and DNA damage repair, while DNA damage accumulation may also affect hormonal status. We review the available reports elucidating involvement of insulin-like growth factor 1 (IGF1), growth hormone (GH), α-melanocyte stimulating hormone (αMSH), and gonadotropin-releasing hormone (GnRH)/gonadotropins in DDR and DNA repair as well as the current understanding of pathways enabling these actions. We discuss effects of DNA damage pathway mutations, including Fanconi anemia, on endocrine function and consider mechanisms underlying these phenotypes. (Endocrine Reviews 41: 1 - 19, 2020).

Fanconi anemia: correlating central nervous system malformations and genetic complementation groups

BACKGROUND

Congenital central nervous system abnormalities in children with Fanconi anemia are poorly characterized, especially with regard to specific genetic complementation groups.

OBJECTIVE

To characterize the impact of genetic complementation groups on central nervous system anatomy.

MATERIALS AND METHODS

Through chart review we identified 36 patients with Fanconi anemia with available brain MRIs at the University of Minnesota (average age, 11.3 years; range, 1-43 years; M:F=19:17), which we reviewed and compared to 19 age- and sex-matched controls (average age, 7.9 years; range, 2-18 years; M:F=9:10). Genotypic information was available for 27 patients (15 FA-A, 2 FA-C, 3 FA-G, and 7 FA-D1 [biallelic mutations in BRCA2 gene]).

RESULTS

Of the 36 patients, 61% had at least one congenital central nervous system or skull base abnormality. These included hypoplastic clivus (n=12), hypoplastic adenohypophysis (n=11), platybasia (n=8), pontocerebellar hypoplasia (n=7), isolated pontine hypoplasia (n=4), isolated vermis hypoplasia (n=3), and ectopic neurohypophysis (n=6). Average pituitary volume was significantly less in patients with Fanconi anemia (P<0.0001) than in controls. Basal angle was significantly greater in Fanconi anemia patients (P=0.006), but the basal angle of those with FA-D1 was not significantly different from controls (P=0.239). Clivus length was less in the Fanconi anemia group (P=0.002), but significance was only observed in the FA-D1 subgroup (P<0.0001). Of the seven patients meeting criteria for pontocerebellar hypoplasia, six belonged to the FA-D1 group.

CONCLUSION

Patients with Fanconi anemia have higher incidences of ectopic neurohypophysis, adenohypophysis hypoplasia, platybasia and other midline central nervous system skull base posterior fossa abnormalities than age- and sex-matched controls. Patients with posterior fossa abnormalities, including pontocerebellar hypoplasia, are more likely to have biallelic BRCA2 mutations.

Central nervous system abnormalities in Fanconi anaemia: patterns and frequency on magnetic resonance imaging

OBJECTIVE

Fanconi anaemia (FA) is an inherited disease associated with congenital and developmental abnormalities resulting from the disruption of a multigenic DNA damage response pathway. This study aimed to define the MRI appearances of the brain in patients with FA in correlation with their genetic and clinical features.

METHODS

A review of the brain MRI in 20 patients with FA was performed. Pituitary size and frequencies of the radiological findings of individuals with FA and age-matched controls were determined.

RESULTS

Abnormalities were identified in 18 (90%) patients with FA, the commonest being a small pituitary (68%, p < 0.01 females and p < 0.001 males). In five cases (25%, p = 0.02), the pituitary morphology was also abnormal. Posterior fossa abnormalities were seen in six cases (30%, p = 0.01) including Chiari I malformation (n = 3), Dandy-Walker variant (n = 2) and cerebellar atrophy (n = 2). Six patients (30%, p = 0.01) had morphological structural variation of the corpus callosum (CC).

CONCLUSION

The incidence of central nervous system (CNS) abnormalities in FA is higher than previously reported, with a midline predominance that points to impact in the early stages of CNS development. MRI brain imaging is important for endocrine assessment and pre-transplant evaluation and can make an important contribution to clinical decision-making.

ADVANCES IN KNOWLEDGE

The incidence of brain structural abnormalities in FA is higher than previously reported, with abnormalities of the posterior fossa, CC and pituitary being common. There is an association with gender and reduction in pituitary size which does not strongly correlate with biochemically evident endocrine abnormality.

Endocrine disorders in Fanconi anemia: recommendations for screening and treatment

CONTEXT

Endocrine problems are common in patients with Fanconi anemia (FA). About 80% of children and adults with FA have at least one endocrine abnormality, including short stature, GH deficiency, abnormal glucose or insulin metabolism, dyslipidemia, hypothyroidism, pubertal delay, hypogonadism, or impaired fertility. The goal of this report is to provide an overview of endocrine abnormalities and guidelines for routine screening and treatment to allow early diagnosis and timely intervention.

EVIDENCE ACQUISITION

This work is based on a comprehensive literature review, including relevant articles published between 1971 and 2014, and proceedings of a Consensus Conference held by the Fanconi Anemia Research Fund in 2013.

EVIDENCE SYNTHESIS

The panel of experts collected published evidence and discussed its relevance to reflect current information about the endocrine care of children and adults with FA before the Consensus Conference and through subsequent deliberations that led to the consensus.

CONCLUSIONS

Individuals with FA should be routinely screened for endocrine abnormalities, including evaluation of growth; glucose, insulin, and lipid metabolism; thyroid function; puberty; gonadal function; and bone mineral metabolism. Inclusion of an endocrinologist as part of the multidisciplinary patient care team is key to providing comprehensive care for patients with FA.

Endocrine evaluation of children with and without Shwachman-Bodian-Diamond syndrome gene mutations and Shwachman-Diamond syndrome

OBJECTIVE

To characterize the endocrine phenotype of patients with Shwachman-Diamond syndrome (SDS).

STUDY DESIGN

Clinically indicated endocrine screening data from 43 patients with SDS or SDS-like presentation were analyzed according to sex, age, and genetic testing. In addition to 25 patients with biallelic Shwachman-Bodian-Diamond syndrome (SBDS) gene mutations, we evaluated 18 patients with cytopenias who were receiving pancreatic enzyme replacement but were without SBDS mutation. We performed a retrospective review of growth records and clinically indicated endocrine evaluations.

RESULTS

Of patients with SBDS mutations, 2 had low stimulated growth hormone levels, 2 had mildly elevated thyrotropin levels, 5 had abnormal glucose levels, and 1 had an elevated follicle-stimulating hormone level (post transplantation). In contrast, 1 patient without SBDS mutations had postprandial hyperglycemia and 3 had mildly low free thyroxine levels without short stature. Endocrine abnormalities were identified in 19% of short patients and 26% of the whole group. Of patients with SBDS mutations, 56% had a height expressed in SD units from the mean for age and sex of <-1.8, in contrast to only 12% of patients without SBDS mutations (38% of the whole group). Body mass index z score was significantly greater in the group with SBDS mutations (P<.001).

CONCLUSION

Although short stature was more common in patients with SBDS mutations, no consistent endocrine phenotype was observed in patients with SDS regardless of genetic testing.

[Fanconi anemia in 2012: diagnosis, pediatric follow-up and treatment]

Fanconi anemia (FA) is a rare genetic disease, transmitted in an autosomal recessive mode. The clinical phenotype is very broad and heterogeneous, related to the wide range of genes involved in this pathology. The classical triad of short height, physical abnormalities, and bone marrow failure is suggestive. The main physical abnormalities found involve the limbs, spinal column, skin, kidneys and urinary tract, and the ORL zone. Recent progress in molecular biology has identified 15 genes whose mutation causes FA chromosomal instability. FA is diagnosed by cytogenetic examination, then specified by molecular analysis. As FA patients may present multiorgan abnormalities and a high risk for neoplasia development, their medical follow-up has to be multidisciplinary and prolonged throughout life. The main challenges of the follow-up are patient information and education. Bone marrow failure, appearing during the first decade, requires close hematological monitoring and for severe cases requires hematopoietic stem cell transplantation, major and specific care with frequent serious complications and high mortality, but this is the only curative treatment in FA. Extrahematological care consists in screening for organ abnormalities and defects as well as monitoring precancerous lesions and tumors.

Peritransplant psychiatric evaluation of patients with fanconi anemia

Patients with Fanconi anemia (FA) referred for stem cell transplantation (SCT) have multiple psychosocial risk factors and often present in distress in the peritransplant period. Twenty-two patients with FA were referred for psychiatry consultation before, during, or after SCT, across a 13-year period at Memorial Sloan-Kettering Cancer Center. The most common diagnoses were mood (50%), adjustment (46%), and anxiety (23%) disorders and delirium (23%); the most common psychiatric symptoms were anxious/depressed (86%), withdrawn (64%), and aggressive (59%) symptoms. Etiology of the diagnoses and symptoms included: chronic childhood illness, physical and/or neurodevelopmental disability, presence of a genetic syndrome, presence of a cancer predisposition syndrome, exposure to therapeutic androgens, and exposure to pediatric SCT. However, the degree of influence of the different factors could not be determined. In addition, other factors such as impact of sibling illness or loss, extent of treatment nonadherence, level and significance of neurodevelopmental pathologies were identified. Future prospective and possibly multicenter studies will need to be generated for a better understanding and more complete factor analysis.

Bone mineral density is normal in children with Fanconi anemia

BACKGROUND

Conflicting data exist regarding whether low bone mineral density (BMD) is associated with Fanconi anemia (FA). The current study identified the frequency of low BMD in FA, expecting low BMD even in childhood and before HCT.

PROCEDURE

Thirty-seven FA patients (18 prior HCT, 19 no prior HCT), participating in an IRB-approved database, had clinical assessment of DXA of lumbar spine BMD. Four had used androgens, one later underwent HCT. Most had used glucocorticoids after HCT (prolonged in five), and one more with no HCT. BMD [in standard deviation units from mean for age (SD), gender, and ethnicity (BMD Z-score)] was then adjusted for height age, and separately for bone maturation (BA). Data were collected for height SD, pubertal stage, and duration since HCT.

RESULTS

BMD Z-score (without adjustment) was <-1 SD in half of FA children. BA-adjusted BMD Z-score was similar. (BA was not usually delayed, although most patients were short.) In contrast, height age-adjusted BMD Z-score was normal in most with FA (only below -2.0 in one child after prolonged glucocorticoids). Mean duration after HCT until DXA test was 6.2 years (median 4.2 years, range 1-18 years).

CONCLUSIONS

Children and adolescents with FA have normal BMD prior to and after HCT, when DXA results are adjusted for bone size/height age. In contrast, BA-adjustment of BMD was not useful in this population. Individual BMD results may be influenced by gonadal function, transplantation status, and prolonged glucocorticoid therapy.

Fanconi anemia and its diagnosis

Fanconi anemia (FA) is a genetically and phenotypically heterogeneous recessive disorder characterized by diverse congenital malformations, progressive pancytopenia, and predisposition to both hematologic malignancies and solid tumors. Congenital anomalies vary from patient to patient and may affect skeletal morphogenesis as well as any of the major organ systems. Although this highly variable phenotype makes accurate diagnosis on the basis of clinical manifestations difficult in some patients, laboratory study of chromosomal breakage induced by diepoxybutane (DEB) or other crosslinking agents provides a unique cellular marker for the diagnosis of the disorder either prenatally or postnatally. Diagnosis based on abnormal response to DNA crosslinking agents can be used to identify the pre-anemia patient as well as patients with aplastic anemia or leukemia who may or may not have the physical stigmata associated with the syndrome. This overview will present our current knowledge regarding the varied phenotypic manifestations of FA and procedures for diagnosis based upon abnormal DNA damage responses.

Genotype-phenotype correlations in Fanconi anemia

Although still incomplete, we now have a remarkably detailed and nuanced picture of both phenotypic and genotypic components of the FA spectrum. Initially described as a combination of pancytopenia with a limited number of physical anomalies, it was later recognized that additional features were compatible with the FA phenotype, including a form without detectable malformations (Estren-Dameshek variant). The discovery of somatic mosaicism extended the boundaries of the FA phenotype to cases even without any overt hematological manifestations. This clinical heterogeneity was augmented by new conceptualizations. There was the realization of a constant risk for the development of myelodysplasia and certain malignancies, including acute myelogenous leukemia and squamous cell carcinoma, and there was the emergence of a distinctive cellular phenotype. A striking degree of genetic heterogeneity became apparent with the delineation of at least 12 complementation groups and the identification of their underlying genes. Although functional genetic insights have fostered the interpretation of many phenotypic features, surprisingly few stringent genotype-phenotype connections have emerged. In addition to myriad genetic alterations, less predictable influences are likely to modulate the FA phenotype, including modifier genes, environmental factors and chance effects. In reviewing the current status of genotype-phenotype correlations, we arrive at a unifying hypothesis to explain the remarkably wide range of FA phenotypes. Given the large body of evidence that genomic instability is a major underlying mechanism of accelerated ageing phenotypes, we propose that the numerous FA variants can be viewed as differential modulations and compression in time of intrinsic biological ageing.

Improved growth velocity during thyroid hormone therapy in children with Fanconi anemia and borderline thyroid function

BACKGROUND

Children with Fanconi anemia (FA) tend to have short stature, mild thyrotropin (TSH) elevation, and borderline low free thyroxine (FT4). Objective was to examine whether thyroid hormone therapy improves linear growth in children with FA and borderline thyroid function tests

PROCEDURE

Thyroid function tests were performed in 63 children with FA. Eight subjects participated in a random order, double-blind, cross-over treatment for 7 months with levothyroxine and for 7 months with placebo. Monitoring included growth measurements and laboratory assays at 1, 4 and 7 months of each phase. A 1 month lead in/wash out period was excluded from analysis of each treatment phase.

RESULTS

The majority (63%) of FA children had borderline thyroid function tests. All eight FA subjects enrolled in the treatment study had FT4 in the lowest third of the normal range of 0.8-1.8 ng/dL (10.3-23.2 pmol/L) [FT4 0.9 +/- 0.1 ng/dL (mean +/- SD), range 0.8-1.2 ng/dL (10.3-15.4 pmol/L)]. TSH (optimal range 0.5-3 mU/L) was borderline elevated in six of eight subjects (4.0 +/- 1.5 mU/L, 1.9-7.3 mU/L). Growth velocity was slow at baseline and improved significantly during the thyroid phase compared to the placebo phase (2.1 +/- 1.2 cm/year vs. 5.4 +/- 1.7 cm/year, P < 0.05).

CONCLUSIONS

Thyroid hormone therapy is safe and may improve linear growth velocity in children with FA who have borderline thyroid function. Subtle hypothyroidism has importance for growth in children. Whether thyroid hormone treatment improves adult height in these children remains to be elucidated.

Recent advances in neuroendocrine imaging

PURPOSE OF REVIEW

Imaging is a critical component of both neuroendocrine lesion identification and anatomic delineation for treatment planning. Cross-sectional and isotopic-based physiologic imaging techniques have, to date, been the radiological modalities of choice. This review focuses on recent advances in imaging that are related to the evaluation of neuroendocrine abnormalities, in particular advances in MRI.

RECENT FINDINGS

Magnetic-resonance perfusion examination of tissue characteristics in the pituitary, adrenal and thyroid glands indicates that, in many cases, adenomas of these glands have distinguishable hemodynamic characteristics relative to the parenchyma of the gland as a whole and to other lesions. Moreover, perfusion metrics might provide a basis for evaluating response to therapy (in the pituitary) and delineation of lesions in the adrenal and thyroid glands. Anisotropy-based imaging techniques show promise in providing direct, relevant information about pituitary tumor involvement of the adjacent cavernous sinuses.

SUMMARY

The most recent methodological advances in the imaging of neuroendocrine disorder involves the continued development and application of MRI, in particular using pulse sequences, which provide a greater insight into the internal structure and physiology of the tissues interrogated, relative to standard sequences.

A role for endogenous and radiation-induced DNA double-strand breaks in p53-dependent apoptosis during cortical neurogenesis

Prenatal exposure to low-dose radiation increases the risk of microcephaly and/or mental retardation. Microcephaly is also associated with genetic mutations that affect the non-homologous end-joining pathway of DNA double-strand break repair. To examine the link between these two causal factors, we characterized the neural developmental effects of acute radiation exposure in mouse littermate embryos harboring mutations in the Ku70 and p53 genes. Both low-dose radiation exposure and Ku70 deficiency induced morphologically indistinguishable cortical neuronal apoptosis. Irradiated Ku70-deficient embryos displayed anatomical damage indicative of increased radiosensitivity in the developing cerebral cortex. Deleting the p53 gene not only rescued cortical neuronal apoptosis at all levels but also restored the in vitro growth of Ku70-deficient embryonic fibroblasts despite the presence of unrepaired DNA/chromosomal breaks. The results confirm the role of DNA double-strand breaks as a common causative agent of apoptosis in the developing cerebral cortex. Furthermore, the findings suggest a disease mechanism by which the presence of endogenous DNA double-strand breaks in the newly generated cortical neurons becomes radiomimetic when DNA end joining is defective. This in turn activates p53-dependent neuronal apoptosis and leads to microcephaly and mental retardation.

Endocrine abnormalities in patients with Fanconi anemia

BACKGROUND

Fanconi anemia (FA) is an inherited disorder with chromosomal instability, bone marrow failure, developmental defects, and a predisposition to cancer. Systematic and comprehensive endocrine function data in FA are limited.

OBJECTIVE

We studied a cohort of FA patients enrolled in the National Cancer Institute's Inherited Bone Marrow Failure Syndrome study.

STUDY DESIGN AND PATIENTS

Retrospective review of the medical records of 45 FA patients (ages 2-49 yr), 23 of whom were intensively evaluated at the National Institutes of Health. Anthropometric measurements, GH, IGF-I, IGF binding protein-3, thyroid, gonadal hormone, lipid levels, glucose homeostasis, brain imaging, and bone mineral density were obtained in these latter patients.

RESULTS

Endocrine abnormalities were present in 73%, including short stature and/or GH deficiency (51%), hypothyroidism (37%), midline brain abnormalities (17%) (these patients had very short stature and 60% were GH-deficient); abnormal glucose/insulin metabolism (39%); obesity (27%); dyslipidemia (55%); and metabolic syndrome (21%). Patients with any endocrine abnormality were shorter than those without; only GH deficiency correlated significantly with short stature (P = 0.01). In addition, 65% of peripubertal or postpubertal patients had gonadal dysfunction. Ninety-two percent of the patients 18 yr or older had osteopenia or osteoporosis.

CONCLUSIONS

Endocrine dysfunction is widespread in children and adults with FA; we expand the FA phenotype to include early onset osteopenia/osteoporosis and lipid abnormalities. Despite the reputation of FA as a progressive, lethal disease, proper management of the full spectrum of FA-related endocrinopathy offers major opportunities to reduce morbidity and improve quality of life. Our findings emphasize the need for comprehensive endocrine and metabolic evaluation and long-term follow-up in patients with FA.