Inverted duplication of chromosome 15 (dic15q11) diagnosed by FISH in a patient with neurological problems.

The family of extra structurally abnormal chromosomes includes supernumerary small chromosomes, which are related to developmental abnormalities. The most common supernumerary index chromosome is inverted duplicated chromosome 15. Two cytogenetic types of inv dup(15) marker chromosomes have been described, each one having different phenotype. Specifically, neurological disorders have been correlated with cytogenetic description of dic(15)(q12 or q13) which contains the Prader-Willi syndrome and Angelman syndrome critical euchromatin regions. On the other hand, cytogenetic description of dic(15)q11 heterocromatin area does not contain the Prader-Willi syndrome/Angelman syndrome critical region and children with this aberration show a normal phenotype. Here, we present the first case of 22-month-boy with cytogenetic description of dic(15)q11 and neurological problems. Specifically the patient was admitted in our department for chromosomal evaluation due to neurological problems. Diagnosis was confirmed by standard cytogenetic techniques and fluorescent in situ hybridization analysis. In addition, we did not identify any abnormal methylation pattern of the small nuclear ribonucleoprotein polypeptide N (SNRPN) locus. The presence of neurological problems in a case of dic(15)q11, suggests that probably imprinted or other genes located in this area are deregulated and it will be interesting future studies to analyze these regions for the presence of imprinted genes.