Table 2

Cytogenetic changes in bone marrow among 48 children with Down’s syndrome for whom cytogenetic results are available

AnomalyFrequency
Constitutional trisomy 21 only5-150 15
Tetrasomy 21 or pentasomy 214
Trisomy 815
Other simple trisomies5-151 10
Chromosome loss5
Balanced translocation6
Unbalanced translocation5-152 9
Monosomy 72
Partial deletion5-153 11
Other structural changes6

  • ↵5-150 Regular trisomy 21 (n = 14); t(21q;21q) (n = 1).

  • ↵5-151 Chromosomes 11 in four cases.

  • ↵5-152 Six involving chromosome 1.

  • ↵5-153 Two involving chromosome 7; five involving chromosome 6; four others.