• PMID: 29998616
• Gene Name: CBX2
• Condition: Disorders/differences of sex development
• Association: Associated
• Mutation: p.Cys132Arg (c.394T>C), p.Cys154fs (c.460delT)
• Population size: 2
• Population details: 2 cases
• Sex: Male
• Infertility type: Male infertility
• Associated genes: NGS

Assembling the jigsaw puzzle: CBX2 isoform 2 and its targets in disorders/differences of sex development

Sproll P, Eid W, Gomes CR, Mendonca BB, Gomes NL, Costa EM, Biason-Lauber A.

BACKGROUND: One of the defining moments of human life occurs early during embryonic development, when individuals sexually differentiate into either male or female. Perturbation of this process can lead to disorders/differences of sex development (DSD). Chromobox protein homolog 2 (CBX2) has two distinct isoforms, CBX2.1 and CBX2.2: the role of CBX2.1 in DSD has been previously established, yet to date the function of the smaller isoform CBX2.2 remains unknown. METHODS: The genomic DNA of two 46,XY DSD patients was analysed using whole exome sequencing. Furthermore, protein/DNA interaction studies were performed using DNA adenine methyltransferase identification (DamID) to identify putative binding partners of CBX2. Finally, in vitro functional studies were used to elucidate the effect of wild-type and variant CBX2.2 on selected downstream targets. RESULTS: Here, we describe two patients with features of DSD i.e. atypical external genitalia, perineal hypospadias and no palpable gonads, each patient carrying a distinct CBX2.2 variant, p.Cys132Arg (c.394T>C) and p.Cys154fs (c.460delT). We show that both CBX2.2 variants fail to regulate the expression of genes essential for sexual development, leading to a severe 46,XY DSD defect, likely because of a defective expression of EMX2 in the developing gonad. CONCLUSION: Our study indicates a distinct function of the shorter form of CBX2 and by identifying several of its unique targets, can advance our understanding of DSD pathogenesis and ultimately DSD diagnosis and management. CI - © 2018 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals, Inc. FAU - Sproll, Patrick AU - Sproll P AUID- ORCID: 0000-0001-5968-2307 AD - Division of Endocrinology, University of Fribourg, Fribourg, Switzerland. FAU - Eid, Wassim AU - Eid W AD - Division of Endocrinology, University of Fribourg, Fribourg, Switzerland. AD - Department of Biochemistry, Medical Research Institute, University of Alexandria, Alexandria, Egypt. FAU - Gomes, Camila R AU - Gomes CR AD - Medical School, University of Sao Paulo, Sao Paulo, Brazil. FAU - Mendonca, Berenice B AU - Mendonca BB AD - Medical School, University of Sao Paulo, Sao Paulo, Brazil. FAU - Gomes, Nathalia L AU - Gomes NL AD - Medical School, University of Sao Paulo, Sao Paulo, Brazil. FAU - Costa, Elaine M-F AU - Costa EM AD - Medical School, University of Sao Paulo, Sao Paulo, Brazil.