A Familial Case of Kallmann Syndrome due to KAL1 Gene Complete Deletion

Kallmann syndrome (KS) is characterized by the association of hypogonadotropic hypogonadism and anosmia. Although the vast majority of KS cases are sporadic, some X-linked recessive (KAL1), autosomal dominant (FGFR1), and autosomal recessive (most commonly GNRHR) modes of inheritance have been described. Two boys were referred to our department because of cryptorchidism and the absence of puberty. Upon laboratory evaluation they were diagnosed with hypogonadotropic hypogonadism. Agenesis of the olfactory bulbs was detected in radiologic tests, and total deletion of the KAL1 gene was detected through multiplex ligation-dependent probe amplification (MLPA). Although cryptorchidism was diagnosed in the siblings, only the older brother suffered from sensorineural hearing loss and right renal agenesis, a feature that had been reported in X-linked KS. We describe herein the clinical heterogeneity of two affected brothers who carry a complete deletion in KAL1; this is the first case of familial Kallmann syndrome due to the complete deletion of the KAL1 gene reported in Korea. (J Korean Soc Pediatr Endocrinol 2011;16:61-65)