title: [Karyological characteristics of Down's syndrome: clinical and theoretical aspects].
abstract: These data have been collected from St. Petersburg Down Syndrome Register that comprises information on 1778 liveborn children with the Down syndrome, including three twin sets, ascertained within 1970-1996. Karyotypes were obtained in 1223 cases, of which 1119 (90.7%) displayed regular trisomy. Mosaicism was found in 44 cases (3.6%), including 21 males and 24 females, and among these one familial case of mosaicism in a daughter and in a healthy mother. Of 70 cases of translocations, 41(5.7%) were Robertsonian D ones. 21 (17 inherited, 16 de novo and 8 of unknown origin), 28 translocations of isochromosomes 21q; 21q (1 inherited translocation 21; 22, 22 de novo and 5 of unknown origin). One child received the anomaly from his 46XX/45XX, t(D;G) mother-carrier. In 6 cases, free trisomy 21 was associated with structural or numerical anomalies: 46XY,t(13;14)mat + 21 in twins, 47XY,t(C;C) + 21, 47XY,t(10;15)pat + 21, 47XY,inv(19)mat + 21, 47XX + 21/48XX + 21 + ring, 48XXX + 21. In 12 families parental mosaicism was shown or suspected. In 6 families one parent had chromosome anomaly, in three cases it was not inherited: t(15;22) and t(6;21) in mothers and an additional small marker in a father. In cases confirmed cytogenetically an increased sex ratio was shown (679 males and 551 females, SR = 1.23), but it was not shown in patients not tested cytogenetically (264 males and 275 females, SR = 0.96, different from the expected 297 males and 242 females, P < 0.01).
authors.affiliation: D. O. Ott Institute of Obstetrics and Cynaecology, Russian Academy of Medical Sciences, Medico-Genetical Centre, and Medical Academy of Postdiploma Education, St. Petersburg.
authors.forename: N V
authors.initials: NV
authors.lastname: Kovaleva
authors.forename: I V
authors.initials: IV
authors.lastname: Butomo
authors.forename: D K
authors.initials: DK
authors.lastname: Verlinskaia
authors.forename: T N
authors.initials: TN
authors.lastname: Il'iashenko
authors.forename: I G
authors.initials: IG
authors.lastname: Pantova
authors.forename: M V
authors.initials: MV
authors.lastname: Prozorova
authors.forename: L E
authors.initials: LE
authors.lastname: Khitrikova
authors.forename: S K
authors.initials: SK
authors.lastname: Shandlorenko
mesh_terms: D002869:Chromosome Aberrations; D025063:Chromosome Disorders; D004314:Down Syndrome / Q000235:genetics* / Q000473:pathology*; D005260:Female; D006801:Humans; D007621:Karyotyping; D008297:Male