Pericentric inversion of chromosome 9[inv(9)(p12q13)]: Its association with genetic diseases

Background: The chromosomal polymorphism of short arms of acrocentric chromosomes and heterochromatin variation of Chromosomes 1, 9, 16 and Y have been reported in humans. The pericentric inversion of Chromosome 9 is commonly seen in normal humans and the frequency estimated to be 1 to 3% in general population and inherited in mendalian fashion or might occur spontaneously without any clinical significance. Aim: The aim of the study was to study the frequency of inv(9) and its clinical correlation with human genetic diseases. Materials and Methods: The chromosomal analysis using GTG-banding was carried out in 3,392 cases suspected with genetic diseases. Results: The pericentric inversion frequency of different chromosomes in our study was 1.24% and frequency of inv(9)(p12q13) was high (64.29%) compared to other pericentric inversions in our study. A high frequency (9.33%) of inv(9)(p12q13) was detected in children with dysmorphic features and congenital anomalies. Conclusion: As a high frequency of inv(9)(p12q13) detected in children with dysmorphic features, the inv(9) definitely have a role in the abnormal phenotype development. During inversion event there might be loss or suppression of euchromatin chromosome region and hence detailed chromosomal break point study is important to understand the clinical significance of the pericentric inversion of Chromosome 9