Systematic analysis of 95 reciprocal translocations of autosomes

Abstract

The statistical analysis of 95 cases of reciprocal translocations involving autosomes detected among about 10,000 patients studied with the R-banding technique gives the following information: 1. An excess of break points exists for chromosome arms 4p,9p, 10q, 21q, and 22q and a deficiency for 1p, 2p, and 6q. Furthermore, there are relatively more break points in the small arms than in the large arms, when the translocation is ascertained through an unbalanced translocation carrier. Except for chromosome 22, an ascertainment bias explain this non random distribution. 2. An excess of telomeric break points exists in all cases of translocations ascertained through unbalanced carriers, and an excess of centromeric break point exists in the case of 3:1 and 1:3 segregations only. These excesses are also explained by an ascertainment bias. 3. The break points are located usually at the junction of the bands (interfaces). 4. The size of the chromosomal imbalance varies in the ascertainment classes. It is very large in cases ascertained through balanced carriers (at least one break point is far from the telomere), large in cases ascertained through abortion, and relatively moderate in cases ascertained through unbalanced translocation carriers (at least one break point is juxta telomeric). 5. An excess of balanced reciprocal translocations exists in our sample of mentally retarded and malformed children (position effect?). 6. An excess of balanced reciprocal translocations (not involving chromosome 21) exists among the trisomics 21 and their parents (interchromosomal effect?). 7. A large excess of maternal transmission exists in cases of 3:1 segregation of reciprocal translocation.

Cytogenetic analysis of sperm chromosomes and sperm nuclei in a male heterozygous for a reciprocal translocation t(5;7)(q21;q32) by in situ hybridisation

“…For some time it has been suggested that interchromosomal effects 26 could increase the rate of other chromosome abnormalities, such as regular non-disjunction in carriers of structural chromosome reorganisations. However, among the 40 reciprocal translocations analysed so far using the human-hamster system, this interchromosomal effect has only been observed in the carrier of a double translocation.…”

Partial distal 12q trisomy with arachnoid cyst

“…There has been 14 reports (16 cases) of partial distal 12q trisomy (Aurias et al, 1978;de Muelenaere et al, 1980;Harrod et al, 1980;Hemming and Brown, 1979;Hirschhorn et al, 1973;Hobolth et al, 1974;Ieshima et al, 1984;Melnyk et al, 1981;Pratt and Bulugahapitiya, 1983;Prieur et al, 1977;Robert et al, 1981;Tajara et al, 1985;Tengstr6m et al, 1985;Zabel and Baumann, 1981). Here we report an additional case of partial distal 12q trisomy which was detected by high resolution chromosome banding technique and review the previously reported patients.…”

Z-DNA immunoreactivity in fixed metaphase chromosomes of primates.

“…Furthermore, these R-bands are considered as the chromosomal segments-that possess the higher concentration of structural genes in human karyotype (41). This would support the assumption that a relationship exists between the presence of Z-DNA.and the control of gene expression (16).…”