Hypogonadotropic Hypogonadism as First Presentation of the Severe Neuroendocrine Disorder Caused by RNF216.

Biallelic pathogenic variants in cause a syndrome characterized by hypogonadotropic hypogonadism, cerebellar ataxia, chorea, and cognitive impairment, a combination first described as Gordon Holmes syndrome (MIM 212840). We report 2 siblings who were referred due to absent or delayed puberty. The older sibling, a 17-year-old male, presented with absence of secondary sexual characteristics and a high-pitched voice. He had normal cognitive development and no anosmia. Clinical examination revealed Tanner stage P1/G1 and bilateral gynecomastia. Blood tests showed low gonadotropin and morning testosterone levels. His 15-year-old sister was referred due to primary amenorrhea. She had spontaneous thelarche and presented with Tanner stage P3/B3. Pituitary magnetic resonance imaging was performed on the brother due to suspicion of Kallmann syndrome, revealing a normal anterior pituitary, a hypoplastic posterior pituitary, and an extensive supratentorial leuko-encephalopathy. Whole-exome sequencing revealed a homozygous pathogenic variant in in both affected siblings. Both parents were heterozygous carriers. pathogenic variants cause a disorder characterized by combined neurodegeneration and reproductive dysfunction. Although neurological symptoms are typically recognized first, they often seem to follow the onset of hypogonadism. This highlights the need for awareness, as hypogonadotropic hypogonadism may be the initial manifestation of this severe neuroendocrine disorder, especially in males.