Ring chromosome 17. Case report and review of the literature.

A 46,XX,r(17) karyotype was observed in a 9-year-old infant with short stature, moderate mental retardation but without other physical abnormality. Eight cases with an r(17) have since been reported: 4 can be compared with our patient, one was detected by amniocentesis, and 3 have Miller-Dieker syndrome. Submicroscopic deletions in the subband p13.3 are probably the cause of Miller-Dieker syndrome. They are present in some cases of r(17) but, in others, this short arm region is entirely preserved.