Mosaicism for trisomy 21 and ring (21) in a male born to normal parents: A case report

► A case of a ring (21) in a patient with mosaicism for trisomy 21 being reported. ► Proband had karyotype 47,XY,+21/47,XY,+21(r)/46,XY; born to normal parents. ► A unique case of occurrence of trisomy 21 and r (21) in same individual. ► Differential expression of hTERT and a linked over expression of TRF2 observed. ► Expression of hTERT and TRF2 correspond to higher percentage of ACA.