Exome Sequencing has a high diagnostic rate in sporadic congenital hypopituitarism and reveals novel candidate genes.

CONTEXT: The pituitary gland is key for childhood growth, puberty, and metabolism. Pituitary dysfunction is associated with a spectrum of phenotypes, from mild to severe. Congenital Hypopituitarism (CH) is the most commonly reported pediatric endocrine dysfunction with an incidence of 1:4000, yet low rates of genetic diagnosis have been reported. OBJECTIVE: We aimed to unveil the genetic etiology of CH in a large cohort of patients from Argentina. METHODS: We performed whole exome sequencing of 137 unrelated cases of CH, the largest cohort examined with this method to date. RESULTS: Of the 137 cases, 19.1% and 16% carried pathogenic or likely pathogenic variants in known and new genes, respectively, while 28.2% carried variants of uncertain significance. This high yield was achieved through the integration of broad gene panels (genes described in animal models and/or other disorders), an unbiased candidate gene screen with a new bioinformatics pipeline (including genes high loss of function intolerance), and analysis of copy number variants. Three novel findings emerged. First, the most prevalent affected gene encodes the cell adhesion factor ROBO1. Affected children had a spectrum of phenotypes, consistent with a role beyond pituitary stalk interruption syndrome. Second, we found that CHD7 mutations also produce a phenotypic spectrum, not always associated with full CHARGE syndrome. Third, we add new evidence of pathogenicity in the genes PIBF1 and TBC1D32, and report 13 novel candidate genes associated with CH (e.g. PTPN6, ARID5B). CONCLUSION: Overall, these results provide an unprecedented insight into the diverse genetic etiology of hypopituitarism.

Comprehensive Identification of Pathogenic Gene Variants in Patients With Neuroendocrine Disorders.

PURPOSE: Congenital hypopituitarism (CH) can present in isolation or with other birth defects. Mutations in multiple genes can cause CH, and the use of a genetic screening panel could establish the prevalence of mutations in known and candidate genes for this disorder. It could also increase the proportion of patients that receive a genetic diagnosis. METHODS: We conducted target panel genetic screening using single-molecule molecular inversion probes sequencing to assess the frequency of mutations in known hypopituitarism genes and new candidates in Argentina. We captured genomic deoxyribonucleic acid from 170 pediatric patients with CH, either alone or with other abnormalities. We performed promoter activation assays to test the functional effects of patient variants in LHX3 and LHX4. RESULTS: We found variants classified as pathogenic, likely pathogenic, or with uncertain significance in 15.3% of cases. These variants were identified in known CH causative genes (LHX3, LHX4, GLI2, OTX2, HESX1), in less frequently reported genes (FOXA2, BMP4, FGFR1, PROKR2, PNPLA6) and in new candidate genes (BMP2, HMGA2, HNF1A, NKX2-1). CONCLUSION: In this work, we report the prevalence of mutations in known CH genes in Argentina and provide evidence for new candidate genes. We show that CH is a genetically heterogeneous disease with high phenotypic variation and incomplete penetrance, and our results support the need for further gene discovery for CH. Identifying population-specific pathogenic variants will improve the capacity of genetic data to predict eventual clinical outcomes.

Metformin, estrogen replacement therapy and gonadotropin inhibition fail to improve insulin sensitivity in a girl with aromatase deficiency.

BACKGROUND: Insulin resistance (IR), abnormal lipid profile, and other features of the metabolic syndrome have been described in CYP19 gene knockout mice and in aromatase-deficient adult men but not in prepubertal affected girls. AIMS: To study insulin sensitivity, as well as the effects of estrogen, metformin and GnRHa treatment on glucose homeostasis, in an aromatase-deficient girl. METHODS: Clinical, metabolic and hormonal follow-up data, from 8 to 12 years of age, is presented. RESULTS: At 9 years of age, IR (HOMA 5.6) and glucose intolerance was detected, along with high serum testosterone (2.28 nmol/l), androstenedione (4.92 nmol/l) and FSH (13.4 mIU/ml) levels. Estrogen replacement was ineffective to suppress gonadotropin and androgen levels, as well as IR. Under metformin therapy, she developed type 2 diabetes and acanthosis nigricans. GnRHa administration for 1 year resulted in marked decreases in gonadotropin and serum androgens, but severe IR persisted. CONCLUSION: Postnatal estrogen replacement and a marked decrease of endogenous androgens failed to improve IR and glucose tolerance. We propose that, in females, the increment of androgens and/or lack of estrogens during fetal life might alter the mechanism of fetal programming of insulin sensitivity.