RT Journal Article SR Electronic T1 De novo der(X)t(X;10)(q26;q21) with features of distal trisomy 10q: case report of paternal origin identified by late replication with BrdU and the human androgen receptor assay (HAR). JF Journal of Medical Genetics JO J Med Genet FD BMJ Publishing Group Ltd SP 242 OP 245 DO 10.1136/jmg.34.3.242 VO 34 IS 3 A1 J Garcia-Heras A1 J A Martin A1 S F Witchel A1 P Scacheri YR 1997 UL http://jmg.bmj.com/content/34/3/242.abstract AB We describe an 11 year old girl with a de novo unbalanced t(X;10) that resulted in a deletion of Xq26-->Xqter and a trisomy of 10q21-->10qter. Her clinical features were of distal trisomy 10q, but she lacked the cardiovascular and renal malformations observed in duplications of 10q24-->10qter and had only moderate mental retardation. X inactivation was assessed on peripheral blood lymphocytes by late replication with BrdU (LR) and the human androgen receptor assay (HAR). By LR the der(X) was inactive without spreading to 10q21-->10qter in all cells. The HAR assay showed skewed methylation of the paternal allele (90%). The correlation of HAR and LR suggests that the der(X) was paternally inherited and is consistent with data from other de novo balanced and unbalanced X;autosome translocations detected in females. This is the first report of parental origin of a de novo trisomy 10q.