A Family With Novel X-Linked Recessive Homozygous Mutation in ANOS1 (c.628_629 del, p.1210fs∗) in Kallmann Syndrome Associated Unilateral Ptosis: Case Report and Literature Review

OBJECTIVE: Kallmann syndrome (KS) may be accompanied by anosmia or hyposmia and midline defects. We present an overweight 16-year-old boy with a lack of puberty, anosmia, congenital right eye ptosis, and normal intellectual function. METHODS: Testicular ultrasonography was performed. Whole-exome sequencing was performed on peripheral blood specimens. Genetic results were confirmed by Sanger sequencing. Anosmia was evaluated quantitatively using the Korean version of the Sniffin’ stick test II. RESULTS: Our patient presented with a complaint of lack of body hair growth and small penile size with no remarkable medical history. He was the second son of third-degree consanguineous healthy parents. Physical examination revealed pubertal Tanner stage I. Congenital right eye ptosis and obesity were noted. Anosmia was confirmed. The laboratory evaluation revealed a low serum level of testosterone, follicle-stimulating hormone, and luteinizing hormone. An X-linked recessive homozygous mutation, c.628_629 del (p.1210fs∗) in exon 5 of the ANOS1 gene was revealed and was also found in the patient’s uncle and great uncle on the mother’s side. CONCLUSION: To date, approximately 28 ANOS1 mutations producing KS phenotypes have been described. However, to the best of our knowledge, this particular X-linked recessive mutation has not been previously reported in KS. Furthermore, ptosis is a rare finding in KS literature. Identification of these cases increases awareness of the phenotypic heterogeneity in novel forms of KS, thereby expediting early definitive treatment, which may prevent the development of further complications.