Microarray analysis of unbalanced translocation in Wolf-Hirschhorn syndrome

Wolf-Hirschhorn syndrome (WHS) is caused by deletions involving chromosome region 4p16.3, which is characterized by growth delay, mild-to-severe mental retardation, hypotonia, facial dysmorphisms and shows extensive phenotypic variability include feeding difficulties, epilepsy and congenital anomalies. Variation in the size of the deletion involving chromosome region 4p16.3 may explain the clinical variation. However, previous studies indicate that duplication for another chromosome region due to an unbalanced translocation elucidate approximately 40-45% WHS patients. Therefore, we used whole genomic cytogenetics array to analyze the entire genome at a significantly higher resolution over conventional cytogenetics to characterize the exact subtelomeric aberration region of one patient with developmental delay and several facial characteristics reminiscent Wolf-Hirschhorn syndrome. Here we report that our patient had 3.7 Mb deletion at the 4p16.2 and 6.8 Mb duplication at 8p23.1 resulted from the unbalanced translocations der(4)t(4;8)(p16.2;p23.1). We confirmed that our patient with monosomy 4p16.2 which is consistent with Wolf-Hirschhorn syndrome and trisomy 8p23.1. The combination of the 4p deletion with 8p partial trisomy explains the complex phenotype presented by our patient.