[Transmission of an 18 ring chromosome in two generations in subjects of normal phenotype]

We report the clinical and cytogenetic findings on three cases with ring chromosome 18. These patients are phenotypically apparently normal. The 18 ring chromosome was segregating in two generations. In the available literature, we found only one report of a r (18) transmission through generations, and none report of case without giving any phenotypic effect or mental retardation.