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A new translocation between chromosomes in the 6-12 and 21-22 groups.

1967; BMJ; Volume: 4; Issue: 3 Linguagem: Inglês

10.1136/jmg.4.3.169

1468-6244

P M Lord, M. D. Casey, B.M. Laurance,

Chromosomal and Genetic Variations

Two families have been reported who show a translocation between chromosomes in the 6-12 group and the 21-22 group (Gray, Dartnall, Creery, and Croudace, 1966a; Gray, Dartnall, and Mac- namara, 1966b).In one family only the mother of the propositus is mentioned as having the trans- location in a balanced form, while in the other family the translocation is present, in a balanced form, in three generations.In each of these fami- lies the translocation, in an unbalanced form, is described in one infant, both of whom died at 4 months of age.The interpretation of the karyotypes is that one infant was trisomic for the long arms of a chromosome in the 6-12 group and that the other was trisomic for the short arms of a similar, or the same, chromosome.In this paper a family is described which has a translocation between chromosomes in the 6-12 and 21-22 groups.This appears in a balanced form in two generations and in an unbalanced form in the third (Fig. 1) in which two sibs, IV. 1 and IV. 2, are apparently trisomic for part of a chromosome in the 6-12 group. Case ReportIV. 1 and IV. 2 are the first and second born girl and boy, respectively, of healthy, mentally normal, unre- lated parents (for dates of birth, see Table I).Both children were late in reaching their milestones and are mentally retarded (Table II).They have similar facies (Fig. 2a and3a), widely patent fontanelles that closed after the age of 3, low-set prominent ears, trans- verse palmar creases, and short incurved fifth digits (Fig. 2b).They also had koilonychia (Fig. 3b), very flat feet, and a lumbar lordotic stance with flexion of the hips and knees that resulted in an unusual gait (Fig. 2c, 3c, 3d).Linkage Studies and Blood Groups.Studies were carried out on the inheritance patterns of red cell