Ring chromosome 3 instability at mitosis

Abstract

Ring chromosome 3 is a rare chromosomal abnormality with a highly variable phenotype principally characterized by pre- and postnatal growth retardation, developmental delay, mild to severe intellectual disability, microcephaly and mild dysmorphic features. The presence of a ring chromosome causes mitotic instability and often results in dynamic mosaicism with cells showing chromosomal or segmental aneuploidies and leading to various phenotypic consequences. We present a case of mitotic instability of ring chromosome 3 in a child with multiple malformations and developmental abnormalities. Aim: The investigation of ring chromosome 3 instability at mitosis. Methods: FISH with DNA probe on chromosome 3. Results: The karyotype of a child - 46,XX,r(3)(p26q29). FISH analysis revealed a mosaic clones derived from ring chromosome 3. Conclusions: The ring chromosomes are unstable at mitosis and lead to the formation of somatic dynamic mosaicism. Mitotic instability of ring chromosome 3 demonstrates the influence of secondary genetic imbalance on severity of symptoms in our patient.