Isodicentric X chromosome in a moderately tall patient with gonadal dysgenesis: lack of effect of functional centromere on inactivation pattern.

An isodicentric X chromosome (46, X idic (X)(pter leads to qter::qter leads to pter)) with a single functioning centromere was found in all lymphocytes and fibroblasts examined from a female patient 171.5 cm in height presenting with primary amenorrhoea. Replication of the abnormal chromosome was consistently late. In some cells the pattern was asymmetrical but the asymmetry did not appear to relate to the position of the active centromere.