The Principles of Clinical Cytogenetics - Extra Materials - Springer

270 Linda Marie Randolph
Table 1
Chromosome Abnormalities in Surveys of 68,159 Liveborn Babies
Type of abnormality Total abnormalities (%)
Sex chromosomes, males
47,XYY 45 (0.103)
47,XXY 45 (0.103)
Other 32 (0.073)
Sex chromosomes, females
45,X 6 (0.024)
47,XXX 27 (0.109)
Other 9 (0.036)
Autosomal trisomies
47,+21 82 (0.120)
47,+18 9 (0.013)
47,+13 3 (0.004)
Other 2 (0.002)
Structural balanced arrangements
Robertsonian translocation
der(D;D)(q10;q10) a 48 (0.070)
der (D;G)(q10;q10) b 14 (0.020)
Reciprocal and insertional translocation 64 (0.093)
Inversion c 13 (0.019)
Structural unbalanced arrangements
Robertsonian 5 (0.007)
Reciprocal and insertional 9 (0.013)
Inversion 1 (0.001)
Deletion 5 (0.007)
Supernumerary 14 (0.020)
Other 9 (0.013)
Total abnormalities
Total babies surveyed
442 (0.648)
Males 43,612
Females 24,547
a der(D;D) refers to Robertsonian translocations involving chromosomes 13,
14, and/or 15.
b der(D;G) refers to Robertsonian translocations involving chromosomes 13,
14, or 15 and 21 or 22.
c Excludes common pericentric inversion of chromosome 9.
Source: Data from ref. 30.
tissue (38). Notwithstanding this caveat, the following frequencies of chromosome abnormalities are
reported in spontaneous abortions: Autosomal trisomies comprise the largest group of 52% of chromosome
abnormalities, followed by 45,X at 19%, triploidy at 16%, and tetraploidy at 6% (37).
The association between advanced maternal age and the incidence of trisomies has been demonstrated
in spontaneous abortions. Of interest is that 45,X appears to be associated with younger maternal
age, with about one-third of 45,X spontaneous abortions coming from women 20–24 year of age (39).
The distribution of trisomies is quite different from that seen at birth or even at amniocentesis, with
30% being trisomy 16, compared to almost negligible rates of trisomy 16 at amniocentesis (37) (see
Table 6).