Triploidy
69,XXY
Also known as: 69 XXY, triploid
69,XXY is triploidy, a complete extra set of chromosomes for a total of 69. Triploidy is usually lethal in early development and is a recognized cause of miscarriage.
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What the notation means
69- total chromosome count (normal is 46)
XXY- sex chromosomes: two X + one Y
Clinical notes
Trisomy 21, Down syndrome
The most common autosomal trisomy compatible with life (~1/700 births). Three copies of chromosome 21. Features: characteristic facies, hypotonia, intellectual disability, ~50% congenital heart disease (AV canal), ↑ risk of AML/ALL and early Alzheimer disease. ~95% free trisomy (nondisjunction, ↑ with maternal age), ~4% Robertsonian translocation, ~1% mosaic.
Trisomy 18, Edwards syndrome
Three copies of chromosome 18. Clenched fists with overlapping fingers, rocker-bottom feet, micrognathia, congenital heart disease; most die in the first year.
Trisomy 13, Patau syndrome
Three copies of chromosome 13. Holoprosencephaly, cleft lip/palate, polydactyly, cutis aplasia; high early mortality.
Klinefelter syndrome (47,XXY and variants)
An extra X in a male (≥1 Y with ≥2 X); 47,XXY is classic, with 48,XXXY and 48,XXYY as higher-grade variants. Tall stature, small firm testes, gynecomastia, infertility, low testosterone. The extra X (or Xs) inactivate as Barr bodies.