refers to the condition in which either of the chromosome in pairs 21 or 22 (known as group G) includes an additional autosome, creating an anomaly. The most common of these two autosome abnormalities is trisomy 21, which is thought to result in Down Syndrome. See also Down Syndrome.
AUTOSOMAL TRISOMY OF GROUP: “The autosomal trisomy of group G refers to the addition of an autosome in a chromosome in groups 21 or 22, which then cause Down Syndrome.”