Normal sperm in a 2;2 homologous male translocation carrier
Carriers of balanced structural chromosomal abnormalities are phenotypically normal but are at high risk of infertility. Translocations usually occur between two non-homologous chromosomes. When occur between homologous chromosomes, an extremely rare event, generally involve acrocentric chromosomes. We present an infertile male referred for genetic analysis with a pure balanced homologous 2;2 translocation and normal sperm in the ejaculate.
Conventional cytogenetic and fluorescence in situ hybridization (FISH) were used in karyotype and sperm analysis, respectively.
Male’s karyotype revealed a pure balanced translocation involving homologous chromosomes 2: 46,XY,t(2;2)(p23;q21.2). Sperm analysis by FISH revealed the presence of 15.8 % of normal and 84.2 % of abnormal spermatozoa for chromosome 2.
This is the first report of confined gonadal mosaicism in a pure homologous non-acrocentric chromosome translocation carrier. Preimplantation genetic diagnosis for chromosome 2 should be offered as a reproductive option.
KeywordsConfined gonadal mosaicism Homologous chromosome translocation Male infertility Preimplantation genetic diagnosis Sperm analysis
From the Centre for Reproductive Genetics A. Barros, Porto, we would like to acknowledge Nuno Barros (B.Sc.), Ana Gonçalves (B.Sc.) and Cláudia Osório for spermiogram evaluation. From the Department of Genetics, Faculty of Medicine, Porto, we would like to acknowledge Filomena Reis (B.Sc.), Fernanda Lemos (B.Sc.) and Vânia Ventura (M.Sc.) for lymphocyte cultures and Susana Fernandes (Ph.D.) for AZF and DAZ molecular studies.
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