New candidate region for mirror hand movements: two patients with terminal 9p deletion and 20p duplication.

The 9p deletion syndrome, which was defined in a detailed way in the previous studies, was characterized by various clinical features such as psychomotor retardation, dysmorphic features and genital anomalies. In contrast to 9p deletion syndrome, 20p duplication was rarely reported in the literature with only a few case reports. Regarding the combination of 9p deletion syndrome and 20p duplication, we found that it was reported in only four patients. In the current study, we aimed to investigate a rare chromosomal rearrangement, partial monosomy 9p and trisomy 20p which was observed in two patients with mirror hand movements. The mirror hand movements was influenced by the combination of genetic and environmental factors. While some cases have been associated with mutations in the DCC, NTN1, RAD51, and DNAL4, there were many cases where the genetic basis of mirror hand movements remained unexplained. There was no alteration detected in genes that were previously known as a cause of mirror hand movement in our patients. This new finding could potentially be attributed to the dosage effect of genes within the 9p deletion or 20p duplication regions or to the genes disrupted within the breakpoint region. Future research focusing on the genes within this genomic locus may hold the potential to uncover novel etiologic reasons for mirror hand movements.