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Ring chromosome 20 mosaicism [r(20)] is a rare chromosomal anomaly associated with minor dysmorphism, mental retardation, autistic behavior, and intractable epilepsy. The proposed mechanism of ring formation is breakage of both short and long arms of a chromosome with subsequent end-to- end fusion. We encountered an 18-month-old boy who presented with developmental delay and mental retardation with seizure episodes, but... |
