Mosaic Ring Chromosome 13 Presented with Isolated Male Infertility: Case Report

Abstract

Ring chromosomes are the result of breakage and re-union of distal ends of chromosomal arms. They have a general frequency of 1 in 50,000 and 1 in 58,000 for chromosome 13. Ring chromosome 13 is usually presented as a syndromic situation stigmatized by particular features, including developmental delay, mental retardation and CNS, skeletal or organ anomalies. As an experimental study, here we report a 31 years old male with no major phenotypic manifestation who was evaluated for azoospermia, while his karyotype revealed presence of a mosaic ring chromosome 13. He had a history of bilateral varicocelectomy and no other major finding in his routine infertility work up was determined. Genetic counseling did not provide any clue for mental disability or dysmorphic features. Pathology examination of the testicular tissue revealed very scarce number of spermatid/spermatozoa within the tubules in conjunction with degrees of maturation arrest mostly in spermatocyte stage. In our knowledge, this is the first report of a ring chromosome 13, manifested by an isolated male infertility.

Keywords: Azoospermia; Case Report; Male infertility; Ring chromosome.

Fig 1

The karyograms prepared from peripheral blood of the patient with ring chromosome 13 including three different lines. A. 46,XY,r(13) (p11.2q34): the line with a ring chromosome 13 with breakpoints at p11.2 and q34. B. 45,XY,-13: a line with a missing chromosome 13. C. 46,XY,dicr(13;13)(p11.2q34;p11.2q34): the line with a double ring of chromosome 13 at the same breakpoints.