Prevalence of endocrine and genetic abnormalities in boys evaluated systematically for a disorder of sex development

Abstract

Study question: What is the likelihood of identifying genetic or endocrine abnormalities in a group of boys with 46, XY who present to a specialist clinic with a suspected disorder of sex development (DSD)?

Summary answer: An endocrine abnormality of the gonadal axis may be present in a quarter of cases and copy number variants (CNVs) or single gene variants may be present in about half of the cases.

What is known already: Evaluation of 46, XY DSD requires a combination of endocrine and genetic tests but the prevalence of these abnormalities in a sufficiently large group of boys presenting to one specialist multidisciplinary service is unclear.

Study, design, size, duration: This study was a retrospective review of investigations performed on 122 boys.

Participants/materials, setting, methods: All boys who attended the Glasgow DSD clinic, between 2010 and 2015 were included in the study. The median external masculinization score (EMS) of this group was 9 (range 1-11). Details of phenotype, endocrine and genetic investigations were obtained from case records.

Main results and the role of chance: An endocrine abnormality of gonadal function was present in 28 (23%) with a median EMS of 8.3 (1-10.5) whilst the median EMS of boys with normal endocrine investigations was 9 (1.5-11) (P = 0.03). Endocrine abnormalities included a disorder of gonadal development in 19 (16%), LH deficiency in 5 (4%) and a disorder of androgen synthesis in 4 (3%) boys. Of 43 cases who had array-comparative genomic hybridization (array-CGH), CNVs were reported in 13 (30%) with a median EMS of 8.5 (1.5-11). Candidate gene analysis using a limited seven-gene panel in 64 boys identified variants in 9 (14%) with a median EMS of 8 (1-9). Of the 21 boys with a genetic abnormality, 11 (52%) had normal endocrine investigations.

Limitations, reasons for caution: A selection bias for performing array-CGH in cases with multiple congenital malformations may have led to a high yield of CNVs. It is also possible that the yield of single gene variants may have been higher than reported if the investigators had used a more extended gene panel.

Wider implications of the findings: The lack of a clear association between the extent of under-masculinization and presence of endocrine and genetic abnormalities suggests a role for parallel endocrine and genetic investigations in cases of suspected XY DSD.

Study funding/competing interest(s): RN was supported by the James Paterson Bursary and the Glasgow Children's Hospital Charity Summer Scholarship. SFA, RM and EST are supported by a Scottish Executive Health Department grant 74250/1 for the Scottish Genomes Partnership. EST is also supported by MRC/EPSRC Molecular Pathology Node and Wellcome Trust ISSF funding. There are no conflicts of interest.

Trial registration number: None.

Keywords: XY DSD; aetiology; copy number variant; disorder of sex development; endocrine abnormaility; genetic abnormality; genitalia.