Meiotic and pedigree segregation analyses in carriers of t(4;8)(p16;p23.1) differing in localization of breakpoint positions at 4p subband 4p16.3 and 4p16.1.
PURPOSE
The purpose of this study was to compare meiotic segregation in sperm cells from two carriers with t(4;8)(p16;p23.1) reciprocal chromosome translocations (RCTs), differing in localization of the breakpoint positions at the 4p subband-namely, 4p16.3 (carrier 1) and 4p16.1 (carrier 2)-and to compare data of the pedigree analyses performed by direct method.


METHODS
Three-color fluorescent in situ hybridization (FISH) on sperm cells and FISH mapping for the evaluation of the breakpoint positions, data from pedigrees, and direct segregation analysis of the pedigrees were performed.


RESULTS
Similar proportions of normal/balanced and unbalanced sperm cells were found in both carriers. The most common was an alternate type of segregation (about 52 % and about 48 %, respectively). Unbalanced adjacent I and adjacent II karyotypes were found in similar proportions about 15 %. The direct segregation analysis (following Stengel-Rutkowski) of the pedigree of carriers of t(4;8)(p16.1;p23.1) was performed and results were compared with the data of the pedigree segregation analysis obtained earlier through the indirect method. The probability of live-born progeny with unbalanced karyotype for carriers of t(4;8)(p16.1;p23.1) was moderately high at 18.8 %-comparable to the value obtained using the indirect method for the same carriership, which was 12 %. This was, however, markedly lower than the value of 41.2 % obtained through the pedigree segregation indirect analysis estimated for carriers of t(4;8)(p16.3;p23.1), perhaps due to the unique composition of genes present within the 4p16.1-4p 16.3 region.


CONCLUSIONS
Revealed differences in pedigree segregation analysis did not correspond to the very similar profile of meiotic segregation patterns presented by carrier 1 and carrier 2. Most probably, such discordances may be due to differences in embryo survival rates arising from different genetic backgrounds.
['Midro|Alina T|AT|', 'Zollino|Marcella|M|', 'Wiland|Ewa|E|', 'Panasiuk|Barbara|B|', 'Iwanowski|Piotr S|PS|', 'Murdolo|Marina|M|', 'Śmigiel|Robert|R|', 'Sąsiadek|Maria|M|', 'Pilch|Jacek|J|', 'Kurpisz|Maciej|M|']
D000328:Adult D056905:Chromosome Breakpoints D020090:Chromosome Segregation D002894:Chromosomes, Human, Pair 4 D005260:Female D005817:Genetic Counseling D006579:Heterozygote D006801:Humans D017404:In Situ Hybridization, Fluorescence D007621:Karyotyping D008297:Male D008540:Meiosis D010375:Pedigree D013094:Spermatozoa D014178:Translocation, Genetic D014314:Trisomy D054877:Wolf-Hirschhorn Syndrome
Reciprocal chromosome translocation FISH mapping Pedigree segregation analysis Meiotic segregation pattern Genetic counseling