Diagnosis and genetic analysis of a case of Waardenburg syndrome type 2 with hypogonadotropic hypogonadism caused by gene deletion.

Hypogonadotropic hypogonadism (HH) is a disease defined by dysfunction of the hypothalamic- pituitary-gonadal hormone axis, leading to low sex hormone levels and impaired fertility. HH with anosmia or hyposmia is known as Kallmann syndrome (KS). Waardenburg syndrome (WS) is a rare autosomal dominant genetic disorder characterized by sensorineural hearing loss and abnormal pigmentation. In this report, we collected the clinical data of a patient with hypogonadotropic hypogonadism and congenital hearing loss of unknown cause. The patient had no obvious secondary sexual characteristics development after puberty, and had a heterozygous deletion (at least 419 kb) in 22q13.1 region (Chr.22:38106433-38525560), which covered the gene. The abnormalities were not found in gene sequencing analysis of both the parents and sister of the proband. By summarizing and analyzing the characteristics of this case, we further discussed the molecular biological etiological association between HH and WS type 2. This case also enriches the clinical data of subsequent genetic studies, and provides a reference for the diagnosis and treatment of such diseases.