RF02 | PMON309 Two Siblings with p.Arg92Trp Variant in NR5A1 Presenting with Testicular Disorder of Sexual Differentiation

Abstract

Introduction Disorders of sexual differentiation (DSD) are conditions of abnormal chromosomal development leading to atypical gonadal and anatomic sexual characteristics. We present the case of two siblings with 46, XX testicular DSD due to a mutation in the nuclear receptor subfamily 5 group A member 1 gene (NR5A1). While there is extensive literature about pathogenic variants of this gene, this is the first variant that has been shown to cause DSD in XX individuals, rather than XY. Case presentation This is the case of a sibling pair with male phenotype and history of hypospadias and hypogonadism in the setting of 46, XX karyotype. Sibling A presented with hypospadias at birth and hypergonadotropic hypogonadism in childhood, initially managed with testosterone. Testicular biopsy revealed bilateral germ cell aplasia with degeneration of seminiferous tubules. Sibling B presented at age 8 with precocious puberty. He had a history of hypospadias and cryptorchidism at birth. Gonadotropins and testosterone levels were prepubertal. Testicular biopsy showed only Sertoli cells. Their adrenal gland and thyroid function was normal, their bone age was advanced. FISH was negative for the SRY gene in both cases, no ovaries or mullerian structures found in pelvic imaging. DSD genetic panels were sent, resulting positive for the R92W variant in NR5A1. Neither of them have intellectual disability; however, sibling B has attention deficit and hyperactivity disorder (ADHD) and obsessive compulsive disorder (OCD). Family history is remarkable for two uncles that have been unable to conceive. Their mother had oligomenorrhea and difficulty conceiving, typical presentation of a female carrier of this mutation. Discussion and conclusions The majority of DSD in individuals with a 46, XX karyotype are due to congenital adrenal hyperplasia (CAH) secondary to 21-hydroxylase deficiency, however, mutations in NR5A1 have been among the most frequently identified genetic causes of gonadal development disorders and are associated with a wide phenotypic spectrum. NR5A1 is an essential transcription factor that regulates target genes crucial for normal reproductive physiology and endocrine function, controlling several steps of adrenal and gonadal development. While there is extensive literature about the phenotype caused by variants of NR5A1 in XY individuals, the recurrent heterozygous p.Arg92Trp NR5A1 variant R92W that our patients have, is the only one that has been shown to cause DSD in XX individuals, with variable degrees of testis development. It has previously been described, however, in women with primary ovarian insufficiency (POI). Morevariants of this gene will continue to arise, playing a pivotal role in reproductive endocrinology. Presentation: Saturday, June 11, 2022 1:00 p.m. - 1:05 p.m., Saturday, June 11, 2022 1:00 p.m. - 1:05 p.m., Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.