ing was created with only 46 chromosomes (4). Another explanation is that the initial zygote had two 21st chromosomes, but during cell division, the 21st chromosome was duplicated. If this were the case, then it will resulted a second grouping with an extra 21st chromosome (4).
             The Robertsonian translocation form of Down syndrome involves the fusion of the long arms (q) of chromosomes 21 and 14, written t (14q21q) (3). T
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