Assignment By R-Banding Of X-Inactivation Status For A Patient With A Sex Chromosome Abnormality

Abstract

An R-banding protocol was developed in order to study the X-inactivation pattern of a patient with a duplicated X chromosome. R-banding was used because it results in the differential banding of the active and inactive X chromosome due to differing replication patterns with the active X being early replicating and the inactive X being late replicating. The results demonstrate that the patient’s normal X chromosome was early replicating as well as the duplicated region of the abnormal X chromosome. This suggests that the observed phenotype is a result of incomplete inactivation of the duplicated X chromosome.