Severe Anomalies Associated With Ring Chromosome

Seven previous cases of ring chromosome 7 (r(7)) have been reported in association with minor anomalies with and without mental retardation [Zackai and Breg, 1973; Nakano and Miyamoto, 1977; DeLozier et al., 1982; Barros et al., 1986; Kohyama et al., 1988; Koiffmann et al., 19901. All of the reported patients had evidence of mosaicism with the r(7) line predominating and low frequencies of double rings, monosomy 7, duplicated rings, normal and other karyotypes. The discussion in these cases has centered on the variation in clinical manifestations in spite of apparently similar chromosome rearrangements and levels of mosaicism. The anomalies in the present patient are far more severe than those reported previously and broaden the spectrum of the ring 7 phenotype.