Characterization by microarray and meiotic segregation study of a der(10)t(10;18) in a patient with infertility and normal phenotype

72% of balanced spermatozoa (Figure 1). No further rearrangement involving chromosome 10 and 18 has been found. Hybridization with X, Y, 18, 13, and 21 chromosome probes revealed no significant increase of gametes with numerical abnormalities (data not shown). Microarray-based comparative genomic hybridization was performed using Agilent® oligonucleotide arrays according to the manufacturer’s instruction (Agilent Human Genome CGH Microarray kit 4x180K®, Inc., Palo Alto, CA, USA). Microarray confirmed a 1-Mb 10q26.3-10qter deletion extending from base 134 427 068 to base 135 434 178 and a 2.5-Mb 18p11.32-18pter amplification extending from base 118 760 to base 2 671 435 according to National Center for Biotechnology Information (NCBI) (build 37-hg19). Chromosomal reorganization may affect the proper progression of gametogenesis disrupting homologous chromosome pairing. In unbalanced translocation, pairing of homologous region and formation of quadrivalent are not possible, and the consequences of meiotic segregation are unclear. To provide a better understanding of the consequences of the der(10) on gametogenesis and try to explain reproductive disorders reported in our patient, a study of meiotic segregation by sperm-FISH was performed. Taking into account the reduced size of unbalanced region, we hypothesized the formation of a bivalent during meiosis. As expected, sperm-FISH showed 72% balanced haploid cells, 28% haploid cells with 10q subtelomeric nullosomy and 18p subtelomeric disomy corresponding to the der(10), suggesting no consequence in the offspring, except the presence of the paternal derivative chromosome. Three unbalanced translocations involving acrocentric chromosomes in infertile patients have been reported so far. In these previously published cases, translocations involved large parts of chromosome with formation of a trivalent configuration at meiosis between the derivative and acrocentric chromosomes with an asynapsed region.1–3 The trivalent can produce alternate or adjacent mode of segregation and may, therefore, explain RPL. In the current study, sperm-FISH results confirmed the absence of new unbalance generated during meiosis. However, we cannot exclude that these unbalances which may compromised fertility can produce disturbances in the proper segregation of other chromosome pairs called as interchromosomal effect (ICE), favoring with the formation of numerical abnormalities in Dear Editor, Carriers of balanced chromosomal rearrangements, including reciprocal, robertsonian translocations, and inversions, have all genetic information conserved. Nevertheless, because of the possibility of defect in chromosome segregation during gametogenesis, carriers of balanced rearrangements have an increased risk of spontaneous abortion and/ or a chromosomally unbalanced child with intellectual deficiency or multiple congenital malformations. Unbalanced translocations in patients with normal phenotype are rarely described. Only three unbalanced translocations involving acrocentric chromosome with meiotic defects were reported in the literature in infertile men.1–3 Here, we report a 39-year-old healthy patient referred to Assisted Reproductive Laboratory for infertility. The patient and his partners present a history of Recurrent Pregnancy Loss (RPL) (6 with the first partner and 3 with his current partner). On physical examination, the patient was phenotypically normal, he has no developmental abnormalities, and the medical history revealed no early neonatal problems and no motor impairment. The semen analysis performed according to the World Health Organization (WHO) 2010 showed normal parameters (volume: 2.5 ml, pH: 7.9, concentration: 15 × 106 spermatoza ml−1, progressive motility: 40%, immotile: 2%, normal form: 5% (Kruger’s criteria) and familial reproductive history failed to show developmental abnormalities or repeated abortion.4 There is no hormonal alteration. Follicle-Stimulating Hormone (FSH), inhibin, and prolactin levels were in the normal range. Cytogenetic analysis of peripheral blood lymphocytes revealed a normal karyotype. Subtelomeric-Fluorescence In Situ Hybridization (FISH) highlighted a derivative chromosome 10 (der(10)) from unbalanced translocation involving the long arm of chromosome 10 and the short arm of chromosome 18. This unbalanced translocation-generated partial 10q monosomy and partial 18p trisomy. Twenty-eight percent of 1000 spermatozoa scored by triple-color FISH analysis exhibited an unbalanced chromosomal equipment corresponding to the presence of the der(10) able to generate the same karyotype than the patient and