Molecular cytogenetic detection of meiotic segregation patterns in sperm nuclei of carriers of 46,XY,t(15;17)(q21; q25).

Structural chromosomal abnormalities in gonadal tissue represent an important category of parentally transmittable unbalanced chromosomal abnormalities to the offspring. A child with multiple anomalies was sent for cytogenetic analysis, and his karyotype was 46,XY,der(17)t(15;17)(q21; q25). This abnormality was transferred from his grandfather to his father and to the proband. In this family, 5 persons (1 female and 4 male) are the carriers of this abnormality. In this study, fluorescence in situ hybridization (FISH) on sperm nuclei of 4 male carriers was studied to determine the distribution of segregation patterns of the balanced translocation 15q;17q. The segregation results showed that the segregation products in the third carrier (the grandfather) were different, but they were not statistically significant. The segregation patterns in the other carriers were similar. Overall, 50.3% of the sperm nuclei (mean value for 4 carriers) analyzed were the result of alternate segregation; 36.9%, of adjacent I segregation; 9.0%, of adjacent II segregation; and 2.4%, of 3:1 segregation; the remaining 1.3% could be diploid sperm nuclei or of 4:0 segregation. Multicolor FISH analysis appears to be a rapid and reliable method for the direct analysis of segregation patterns in sperm nuclei of carriers of balanced reciprocal translocation, and it also provides interesting information for determining the possible risks for the offspring.