Ring Chromosome 8

Ring chromosome 8 (RC8) is one of the least frequent ring chromosomes (RCs). It is usually detected on metaphase spreads during G-banding karyotyping. However, additional methods allow to establish RC structure, and more accurately evaluate dynamic mosaicism originated due to mitotic instability of RCs. The RC structure, additional ring variants, monosomy due to RC loss can contribute to the patient’s phenotype and affect the prognosis of the disease. Generally, the presence of the RC8 is usually accompanied by low birth weight and body length, short stature, microcephaly, developmental delay, intellectual disability, facial dysmorphic features, and anomalies of fingers and feet. Hyperactivity and pleasant personality are usually reported. When counseling families with a child with a RC8, it should be remembered that one of the parents might be a carrier of polymorphic inversion and amplifications in 8p23.1.