Table 1:

Common Autosomal and Sex Chromosome Aneuploidies and Microdeletion Syndromes

Condition	Common Name(s)	Estimated Prevalence in Newborns
Autosomal Chromosome Aneuploidies
Trisomy 21	Down syndrome	1 in 800 newborns Most common autosomal chromosome aneuploidy among live births Frequency is strongly dependent on maternal age
Trisomy 18	Edwards syndrome	1 in 5,000 newborns More common in fetuses that do not survive to term Frequency increases with maternal age
Trisomy 13	Patau syndrome	1 in 16,000 newborns Frequency increases with maternal age
Sex Chromosome Aneuploidies
Monosomy X (45, X)	Turner syndrome	1 in 2,000–2,500 newborn females More common in fetuses that do not survive to term
XXY syndrome (47, XXY)	Klinefelter syndrome	1 in 500–1,000 newborn males Most common sex chromosome aneuploidy Variants are much rarer (e.g., XXXY, XXXXY, XXYY, XX male), occurring in 1 in 50,000 or fewer newborn males
Triple X syndrome (47, XXX)	Trisomy X	1 in 1,000 newborn females
XYY syndrome (47, XYY)	Jacob's syndrome	1 in 1,000 newborn males
Microdeletion Syndromes
15q11–q13 deletion (loss of function of active genes in regions on chromosome 15)	Prader-Willi syndrome	1 in 10,000–30,000 newborns
15q11–q13 deletion (loss of function of gene UBE3A on chromosome 15)	Angelman syndrome	1 in 12,000–20,000 newborns
22q11.2 deletion syndrome	DiGeorge syndrome	1 in 4,000 newborns
5p deletion syndrome	Cri-du-chat syndrome	1 in 20,000–50,000 newborns
1p36 deletion syndrome	Monosomy 1p36	1 in 5,000–10,000 newborns

Source: Adapted from the U.S. National Library of Medicine Genetics Home Reference.¹