RESUMO
Seven families with translocations t(11; 22) identified at our Institute and analysis of the literature showed that the imbalance resulted from such translocations is always due to nondisjunction 3:1. Nondisjunction occurs more often in the 1st meiotic division, and is more rare in the second one. Expressed prezygotic selection against spermia with an additional chromosome greatly increases the risk of having an imbalanced child for the women-carriers as compared to men-carriers. The phenotype of the patients with +der(22)t(11; 22) is composed of the features characteristic for trisomy 22q (cleft lip and palate, preauricular papillomas and fistulas, rectal atresia or stenosis) and trisomy 11q (long philtrum with the upper lip hanging over, renal al; asia and hypoplasia). Diaphragmatic hernias are found to be common for the patients with +der(22)t(11; 22).
Assuntos
Cromossomos Humanos Par 11 , Cromossomos Humanos Par 22 , Translocação Genética , Feminino , Triagem de Portadores Genéticos , Humanos , Recém-Nascido , Masculino , Não Disjunção Genética , Gravidez , TrissomiaRESUMO
Phenotypic picture for two cytogenetically different variants of trisomy 4p (with and without involvement of the proximal part of 4q) obtained on the data of Minsk Teratologic Center and on the review of 64 cases from the world literature is presented. Mathematical evaluation of intrapair, within- and interfamilial similarity, depending on a duplicated segment, is given. It is shown that phenotypic similarity among patients in case of duplicated distal segments 4p15(16)----pter is significantly greater, while as the size of trisomic segment increases, the similarity goes down. Significant excess of within- over interfamilial similarity is shown, the fact that may be ascribed to a greater similarity of the genofonds in the group of relatives.
Assuntos
Cromossomos Humanos Par 4 , Trissomia , Feminino , Humanos , Lactente , Recém-Nascido , FenótipoRESUMO
The family, where 2 children had partial trisomy 2q33-q ter, due to paternal translocation t(2;18) (q33;p11.1), was examined. The analysis of 36 cases of trisomy 2q showed that the forms connected with parental chromosomal rearrangement prevailed in the genesis of trisomy 2q. Moreover, the balanced carrier-mothers were more common than fathers. The 2q34-q ter segment may be considered "critical" for occurrence of trisomy 2q syndrome. In case of equal triplication, the similarity between the patients within the same family is greater than between those from different families. The value of intragroup similarity between the patients with equal trisomies may be used for evaluation of phenotypical similarity at different triplicated segments.
