Sperm-FISH analysis in a pericentric chromosome 1 inversion, 46,XY,inv(1)(p22q42), associated with infertility.
No phenotypic effect is observed in most inversion heterozygotes. However, reproductive risks may occur in the form of infertility, spontaneous abortions or chromosomally unbalanced children as a consequence of meiotic recombination between inverted and non-inverted chromosomes. An odd number of crossovers within the inverted segment results in gametes bearing recombinant chromosomes with a duplication of the region outside of the inversion segment of one arm and a deletion of the terminal segment of the other arm [dup(p)/del(q) and del(p)/dup(q)]. Using fluorescence in-situ hybridization (FISH), the chromosome segregation of a pericentric inversion of chromosome 1 was studied in spermatozoa of a inv(1)(p22q42) heterozygous carrier. Three-colour FISH was performed on sperm samples using a probe mixture consisting of chromosome 1p telomere-specific probe, chromosome 1q telomere-specific probe and chromosome 18 centromere-specific alpha satellite DNA probe. The frequency of the non-recombinant product was 80.1%. The frequencies of the two types of recombinants carrying a duplication of the short arm and a deletion of the long arm, and vice versa, were respectively 7.6 and 7.2%, and these frequencies were not statistically significant from the expected ratio of 1:1. Sperm-FISH allows the further understanding of segregation patterns and their effect on reproductive failure and allows an accurate genetic counselling.
Chantot-Bastaraud
S
S
AP-HP, Hôpital Tenon, Service d'Histologie, Biologie de la Reproduction et Cytogénétique, Université Pierre et Marie Curie-Paris6, EA 1533, Paris, France.
Ravel
C
C
Berthaut
I
I
McElreavey
K
K
Bouchard
P
P
Mandelbaum
J
J
Siffroi
J P
JP
D000328:Adult; D007446:Chromosome Inversion; D002878:Chromosomes, Human, Pair 1; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D007248:Infertility, Male / Q000235:genetics* / Q000473:pathology; D008297:Male; D008957:Models, Genetic; D011995:Recombination, Genetic; D013094:Spermatozoa / Q000473:pathology*