8474 SOX11 mutations cause hypogonadotropic hypogonadism through both hypothalamic and pituitary level deficits

Abstract Disclosure: B. Sun: None. S. Stockman: None. M. Stamou: None. L. Plummer: None. K. Salnikov: None. D. Kotan: None. K. Topaloglu: None. S.B. Seminara: None. R. Balasubramanian: None. Purpose: Human SOX11 mutations cause Coffin-Siris Syndrome (CSS) which is clinically characterized by aplasia or hypoplasia of the distal phalanx/nail of the fifth digit, developmental delay, cognitive impairment, and distinctive facial features. Recent studies show hypogonadotropic hypogonadism (HH) occurs in ∼20% of patients with SOX11 mutations. The genotypic-phenotypic spectrum of SOX11 mutations in patients presenting with Idiopathic Hypogonadotropic Hypogonadism (IHH) is unknown. Methods: Exome sequencing data from 1810 unrelated IHH probands (anosmic and normosmic forms) were reviewed for SOX11 rare sequence variants (RSVs) [minor allele frequency <0.1%]. Rare variant association analysis (RVAS) and domain-based enrichment for SOX11 RSVs was performed between the IHH and gnomAD population cohort. RSVs predicted as pathogenic/likely pathogenic by ACMG criteria were deemed as pathogenic RSVs and detailed phenotypic analysis was undertaken for these variants. Results: A total of 4 pathogenic SOX11 RSVs were identified in 5 IHH cases. RVAS analysis showed that SOX11 inactivating RSVs (frameshift/non-sense) across the entire protein was enriched in the IHH cohort (2 RSVs in 3 IHH cases (p.S303X [de-novo]; p p.S345Afs*13); p<0.0001) while SOX11 missense RSVs was enriched only within the SOX11-HMG domain (2 RSVs in 2 IHH cases (p.G84D [de-novo]; p.P114S; p=0.003). Phenotypic review of individuals with pathogenic SOX11-RSVs revealed a spectrum of endocrine defects including: anosmic and normosmic forms of IHH, growth-hormone (GH) deficiency, neuroimaging defects (pituitary microadenoma and hypothalamic mass), and hypothyroidism. Additionally, we also identified a pathogenic SOX11 HMG domain RSV in a patient with functional HH (p.R100Q). CSS-associated features were present in almost all individuals with pathogenic SOX11 RSVs. Conclusions: This study validates SOX11 mutations as causal for IHH and reiterates the critical importance of the SOX11-HMG domain in disease pathogenesis. The spectrum of endocrine abnormalities in SOX11-related human disorders includes IHH, functional HH, GH deficiency, pituitary lesions, and hypothyroidism. The association of congenital anosmic and normosmic forms of IHH, functional HH, and anatomic abnormalities of the pituitary gland suggest that the pathogenesis of HH in SOX11-disorder may stem from both hypothalamic and pituitary level deficits. Presentation: 6/1/2024