Hypogonadotropic hypogonadism-retinitis pigmentosa syndrome

Hypogonadotropic hypogonadism-retinitis pigmentosa syndrome, also known as Boucher-Neuhäuser syndrome (BNS), is a rare genetic disorder characterized by the triad of hypogonadotropic hypogonadism, retinitis pigmentosa (or chorioretinal dystrophy), and progressive cerebellar ataxia. The condition affects multiple body systems including the endocrine system, the eyes, and the central nervous system. Hypogonadotropic hypogonadism results from insufficient production of gonadotropin-releasing hormone or gonadotropins (LH and FSH), leading to delayed or absent puberty and infertility. Retinitis pigmentosa causes progressive degeneration of the retina, resulting in night blindness, loss of peripheral vision, and potentially severe visual impairment. Cerebellar ataxia manifests as progressive difficulties with coordination, balance, and gait. The syndrome is caused by biallelic pathogenic variants in the PNPLA6 gene, which encodes neuropathy target esterase, an enzyme involved in phospholipid metabolism. This enzyme plays a critical role in maintaining cellular membrane integrity, particularly in neurons and photoreceptors. The onset of symptoms is variable but typically begins in childhood or adolescence, with cerebellar and visual symptoms often progressing over time. Additional features may include intellectual disability and peripheral neuropathy in some patients. There is currently no curative treatment for Boucher-Neuhäuser syndrome. Management is supportive and multidisciplinary, involving hormone replacement therapy for hypogonadism, ophthalmologic monitoring and low-vision aids for retinal degeneration, and physical therapy and rehabilitation for cerebellar ataxia. Genetic counseling is recommended for affected families. Prognosis varies depending on the severity and progression of symptoms.

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