title: Attenuated phenotype in a child with trisomy for 1q due to unbalanced X;1 translocation [46,X,der(X),t(X;1)(q28;q32.1)].
abstract: We report a case of an X;1 translocation in a 9-month-old female infant with mild dysmorphic features and developmental delay. High-resolution chromosome analysis revealed a de novo, unbalanced translocation between chromosomes X and 1 [46,X,der(X),t(X;1)(q28;q32.1)]. Breakpoints on the derivative X and the size of the translocated segment have been defined by fluorescence in situ hybridization (FISH) with Xq and 1q specific probes. The rearrangement in this patient results in monosomy for Xq28-qter and trisomy for 1q32.1-qter. Replication studies demonstrated late replication of the derivative X in 80% of the observed cells, with the exception of 20% of the cells where X inactivation failed to spread into the translocated 1q segment. Patients with pure trisomy for the distal segment of 1q present a considerably more severe phenotype compared to that seen in our patient, including facial dysmorphisms, urogenital and cardiac anomalies. We suggest that the absence of many of the characteristic features for trisomy 1q in our patient, may reflect a mosaic pattern of inactivation of the translocated autosomal segment on the derivative X chromosome.
authors.affiliation: Department of Molecular and Human Genetics, Baylor College of Medicine, and Texas Children's Hospital, Clinical Care Center, 6621 Fannin, Houston, TX 77030, USA.
authors.forename: Svetlana A
authors.initials: SA
authors.lastname: Yatsenko
authors.forename: Trilochan
authors.initials: T
authors.lastname: Sahoo
authors.forename: Melinda
authors.initials: M
authors.lastname: Rosenkranz
authors.forename: Roberto
authors.initials: R
authors.lastname: Mendoza-Londono
authors.forename: Rizwan
authors.initials: R
authors.lastname: Naeem
authors.forename: Fernando
authors.initials: F
authors.lastname: Scaglia
mesh_terms: D000015:Abnormalities, Multiple; D002878:Chromosomes, Human, Pair 1 / Q000235:genetics*; D041321:Chromosomes, Human, X / Q000235:genetics*; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007223:Infant; D010641:Phenotype; D012720:Severity of Illness Index; D014178:Translocation, Genetic; D014314:Trisomy / Q000235:genetics*