Mental retardation, unusual facies, and abnormal nails associated with a group-G ring chromosome. A case report on two unrelated cases.

This is a report on two unrelated male children with a stable ring chromosome of the G group, associated with severe mental retardation, an unusual facies, and pachyonychia congenita of the toe nails. The facial appearance was so strikingly similar, that the diagnosis in the second case was suspected clinically. Although there have been a number of reports of ring formation, simple deletion, or monosomy in the G-group autosomes (Lejeune et al, 1964; Reisman et al, 1966; Al-Aish et al, 1967; Hall, Fredga, and Svenningsen, 1967; Hoefnagel et al, 1967; Schulz and Krmpotic, 1968; Weleber, Hecht, and Giblett, 1968; Blank and Lorber, 1969), our two patients do not entirely resemble any of the previously reported cases, as far as can be judged from the clinical descriptions and published photographs.