<unk>  is a rare aberration of chromosome<unk> . A human cell has one pair of identical chromosomes on chromosome<unk> . With the<unk> , one chromosome of the pair is not complete, because a part of the sequence of the chromosome is missing. One chromosome has the normal length and the other is too short. In<unk> .1, the '1' stands for chromosome<unk> , the 'q' stands for the long arm of the chromosome and '21.1' stands for the part of the long arm in which the deletion is situated. The<unk>  is a form of the<unk> .1 copy number variations, and it is a deletion in the distal area of the<unk> .1 part. The CNV leads to a very variable phenotype, and the manifestations in individuals are quite variable. Some people who have the<unk>  can function in a normal way, while others have symptoms of mental retardation and various physical anomalies.<unk> .1 microdeletion is a very rare chromosomal condition. Only 46 individuals with this deletion have been reported in medical literature as of August 2011.
1q21.1 deletion syndrome
13q deletion syndrome
22q13 deletion syndrome
2q37 deletion syndrome
22q11.2 distal deletion syndrome
9q34 deletion syndrome
1p36 deletion syndrome
Chromosome 5q deletion syndrome