The duplication includes ~3.75 Mb between the distal and proximal ORDRs at either end of band<unk> .1. The copy number of the adjacent repeats may also be altered. The<unk>  cannot be distinguished using conventional cytogenetics from high level copy number variation of the repeats themselves. Both de novo cases and families with transmitted duplications from parents of both sex are known. The duplication is believed to arise de novo as a result of non-allelic homologous recombination (NAHR) between the proximal and distal ORDRs. NAHR is also thought to give rise to the reciprocal microdeletion syndrome, the polymorphic inversion between the ORDRs and a variety of other large scale abnormalities involving the short arm of chromosome 8.
8p23.1 duplication syndrome
22q11.2 duplication syndrome
13q deletion syndrome
2q37 deletion syndrome
22q13 deletion syndrome
22q11.2 distal deletion syndrome
1q21.1 deletion syndrome
7q11.23 duplication syndrome