A case with Down syndrome presenting 21q22q translocation: Differential diagnosis

Abstract

Robertsonian translocations (ROBs) are the most common chromosomal rearrangemets. ROBs are whole-arm rearrangements between the acrocentric chromosomes chromosomes 13, 14, 15, 21, and 22. ROBs can be classified into 2 groups depending on their frequency of occurrence, common [rob(13q14q) and rob(14q21q)] and rare (all remaining possible nonhomologous combinations). Each of the rare types make up only 0.8% to 3.7% of the total number of ROBs. ROBs involving chromosome 21 are found in approximately 5% of patients with Down syndrome (DS). The most common nonhomologous ROB in DS is rob(14q21q). Rob(21q;22q) is an uncommon ROB. In this case a 4-year-old boy with 21q22q translocation is discussed briefly. The literature about ROBs was reviewed.