Complex chromosomal

rearrangement leading to partial trisomy 22 SUMMARY We have examined a boy with a peculiar facial appearance and mental retarda-tion. Cytogenetic studies showed 47,XY, mono-somy 22, + two marker chromosomes, MI and M2. The karyotype is interpreted as functionally partial trisomy 22. Chromosome analyses of both parents and three sibs were normal. Several cases of trisomy 22 (non-mongoloid trisomy G) have been described.1-5 There is a wide variation in the phenotypic appearance ofthese cases. However, there are many similarities which allow the descrip-tion of a specific syndrome. It has been suggested by Zellweger et al5 that trisomy 22 syndrome (T22), ca