Severe phenotype resulting from an active ring X chromosome in a female with a complex karyotype: characterisation and replication study.

AUTOR(ES)

Stavropoulou, C

RESUMO

We report on the characterisation of a complex chromosome rearrangement, 46,X,del(Xq)/47,X,del(Xq),+r(X), in a female newborn with multiple malformations. Cytogenetic and molecular methods showed that the del(Xq) contains the XIST locus and is non-randomly inactivated in all metaphases. The tiny r(X) chromosome gave a positive FISH signal with UBE1, ZXDA, and MSN cosmid probes, but not with a XIST cosmid probe. Moreover, it has an active status, as shown by a very short (three hour) terminal BrdU pulse followed by fluorescent anti-BrdU antibody staining. The normal X is of paternal origin and both rearranged chromosomes originate from the same maternal chromosome. We suggest that both abnormal chromosomes result from the three point breakage of a maternal isodicentric idic(X)(q21.1). Finally, the phenotype of our patient is compared to other published cases and, despite the absence of any 45,X clone, it appears very similar to those with a 45,X/46,X,r(X) karyotype where the tiny r(X) is active.

Documentos Relacionados

• Three patients with ring (X) chromosomes and a severe phenotype.
• Structural aberration of the X chromosome in a patient with gonadal dysgenesis: an approach to karyotype-phenotype correlation.
• Complex karyotype including ring chromosome 11 in a patient with acute myeloid leukemia: case report
• Trisomy 18 syndrome with an unusual karyotype: possible double isochromosome.
• An unstable ring chromosome in a female infant with hypotonia, seizures, and retarded development.