<unk>  or 1q21.1 (recurrent) microduplication is a rare aberration of chromosome 1. In a common situation a human cell has one pair of identical chromosomes on chromosome 1. With the<unk>  one chromosome of the pair is over complete, because a part of the sequence of the chromosome is duplicated twice or more. In 1q21.1, the '1' stands for chromosome 1, the 'q' stands for the long arm of the chromosome and '21.1' stands for the part of the long arm in which the duplication is situated. Next to the duplication syndrome, there is also a 1q21.1 deletion syndrome. While there are two or three copies of a similar part of the DNA on a particular spot with the duplication syndrome, there is a part of the DNA missing with the deletion syndrome on the same spot. Literature refers to both the deletion and the duplication as the 1q21.1 copy-number variations (CNV). The CNV leads to a very variable phenotype and the manifestations in individuals are quite variable. Some people who have the syndrome can function in a normal way, while others have symptoms of developmental delays and various physical anomalies.
1q21.1 duplication syndrome
13q deletion syndrome
2q37 deletion syndrome
1q21.1 deletion syndrome
22q11.2 duplication syndrome
22q13 deletion syndrome
Chromosome 5q deletion syndrome
22q11.2 distal deletion syndrome