A computer model for the study of segregation in reciprocal translocation carriers: Application to 20 new cases

Abstract

We report on a computer program that, given the breakpoints and the chromosomes involved in a translocation, generates all the possible imbalanced gametes, calculates their corresponding imbalances, and arranges them in order of increasing imbalance. When compared to current, more cumbersome criteria from the literature, both methods agreed on 196 cases of 199 (greater than 98%). When compared to observed data from families with aneuploid offspring, both our program and the other reported methods yield a rate of accurate prediction of 87%. The use of the program is illustrated in 20 new translocations from our laboratory. The possible influence of crossing over in meiosis I in altering the gamete that is most likely to be passed to aneuploid live births is discussed.

Cytogenetic analysis of meiotic segregation in sperm from two males heterozygous for reciprocal translocations using PRINS and humster techniques

“…1988). Retro spective surveys have demonstrated that a given translocation always imbalances through an identical imbalance mode (De Arce et al, 1986). A number of parameters have been suggested to determine the viability of imbalances such as the chromo some size of imbalance, the position of breakpoints and the genetic background.…”

“…An exact estimation of the risk of these different imbal ances in the progeny of translocation carriers is complex because the majority of detected reciprocal translocations are unique. Nevertheless, several methods for predicting the risk of imbalance at term have been proposed essentially based on the analysis of the chromosomal pachytene quadrivalent (Jalbert et al, 1980;Daniel, 1979;De Arce et al. 1986).…”

Analysis of chiasma frequency and first meiotic segregation in a human male reciprocal translocation heterozygote, t(1;11) (p36.3;q13.1), using fluorescence in situ hybridisation

“…These criteria have formed the bases of segregational models for the assessment of repro ductive risks (Jalbert and Sele, 1979;Jalbert et al, 1980;de Arce et al, 1986). However, the true meiotic mechanisms responsible for determining how structural rearrangements se gregate remain unknown.…”

Deletion of chromosome 3 and a 3;20 reciprocal translocation demonstrated by chromosome painting

“…The analysis of the fused region observed on chromosome der (20) Although several cases of translocations involving chromosomes 3 and 20 has been published [Archidiacon0 et al, 1979;De Arce et al, 1986;Nielsen et al, 1986;Jacobs et al, 1974;Stoll and Levy, 19741, none of them were involved in a similar reciprocal translocation. Stoll and Levy [1974] described a patient with a simple 3;20 translocation.…”

“…Different from chromosome 3, this chromosome has frequently been described in anomalies either by the presence of duplication of its short arm or by participating in translocations [Nielsen et al, 1986;Borgaonkar, 1991;Palmer et al, 1976;Bou6 and Gallano, 19841. Some cases of deletions of the short arm of chromosome 3 have been published [Hertz et al, 1988;Short et al, 1986;Sinchong et al, 1981;Naritomi et al, 1988;Kogame and Kudo, 1979;Wyandt et al, 19801. Clinical delineations of the 3p proximal deletion syndrome have also been published [Neri et al, 1984;Naritomi et al, 19881. Very few cases of t(3;20) have been described [Archidiacono et al, 1979;De Arce et al, 1986;Nielsen et al, 1986;Jacobs et al, 1974;Stoll and Levy, 19741. Most of these were identified through the presence of a partial trisomy in families with carriers of the balanced translocation.…”