Expanding the Genetic Spectrum of ANOS1 Mutations in Patients with Congenital Hypogonadotropic Hypogonadism

• Autor(a) principal: Gonçalves, CI
• Data de Publicação: 2017
• Outros Autores: Fonseca, F, Borges, T, Cunha, F, Lemos, MC
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.17/2711
• topic: HCC END; Alleles; Cross-Sectional Studies; DNA Mutational Analysis; Exons; Extracellular Matrix Proteins/genetics; Gene Frequency; Hypogonadism/congenital; Hypogonadism/genetics; Kallmann Syndrome/genetics; Mutation; Nerve Tissue Proteins/genetics; Pedigree

STUDY QUESTION: What is the prevalence and functional consequence of ANOS1 (KAL1) mutations in a group of men with congenital hypogonadotropic hypogonadism (CHH)? SUMMARY ANSWER: Three of forty-two (7.1%) patients presented ANOS1 mutations, including a novel splice site mutation leading to exon skipping and a novel contiguous gene deletion associated with ichthyosis. WHAT IS KNOWN ALREADY: CHH is characterized by lack of pubertal development and infertility, due to deficient production, secretion or action of GnRH, and can be associated with anosmia/hyposmia (Kallmann syndrome, KS) or with a normal sense of smell (normosmic CHH). Mutations in the anosmin-1 (ANOS1) gene are responsible for the X-linked recessive form of KS. STUDY DESIGN, SIZE, DURATION: This cross-sectional study included 42 unrelated men with CHH (20 with KS and 22 with normosmic CHH). PARTICIPANTS/MATERIALS, SETTING, METHODS: Patients were screened for mutations in the ANOS1 gene by DNA sequencing. Identified mutations were further investigated by RT-PCR analysis and multiplex ligation-dependent probe amplification (MLPA) analysis. MAIN RESULTS AND THE ROLE OF CHANCE: Hemizygous mutations were identified in three (7.1%) KS cases: a novel splice acceptor site mutation (c.542-1G>C), leading to skipping of exon 5 in the ANOS1 transcript in a patient with self-reported normosmia (but hyposmic upon testing); a recurrent nonsense mutation (c.571C>T, p.Arg191*); and a novel 4.8 Mb deletion involving ANOS1 and eight other genes (VCX3B, VCX2, PNPLA4, VCX, STS, HDHD1, VCX3A and NLGN4X) in KS associated with ichthyosis. LIMITATIONS, REASONS FOR CAUTION: Objective olfactory testing was not performed in all cases of self-reported normosmia and this may have underestimated the olfactory deficits. WIDER IMPLICATIONS OF THE FINDINGS: This study further expands the spectrum of known genetic defects associated with CHH and suggests that patients with self-reported normal olfactory function should not be excluded from ANOS1 genetic testing. STUDY FUNDING/COMPETING INTEREST(S): This study was funded by the Portuguese Foundation for Science and Technology. The authors have no conflicts of interest.