A complex rearrangement, including a deleted 8q, in a case of Langer-Giedion syndrome.

A 10-month-old infant with failure to thrive, delayed development, mild dysmorphia, cardiac anomalies, and cryptorchidism was referred for cytogenetic evaluation. Routine GTG-banded analysis revealed a modal number of 46 chromosomes, which contained an obvious complex rearrangement involving chromosomes 1, 8, and 14. Parental chromosomes were normal. Following high resolution techniques, this de novo rearrangement demonstrated an intraband deletion and was designated as [46,XY,t(1;8;14)(1pter----1p13.1::14q12----14pter++ +;1qter----1p13.1::8q24.13----8qter; 14qter----14q12::8p23.3----8q24.11:)]. Although deletions have been implicated as possibly responsible for abnormal phenotypes in patients with de novo "balanced rearrangements", in most cases, they could not be demonstrated. The present case is only the second instance documenting a subtle intraband deletion in association with a complex translocation. Fourteen of the reported 18 patients with an 8q deletion (including this infant) have Langer-Giedion syndrome, suggesting an etiologic relationship. However, the same deletion is not present in all cases.

Duplication of chromosome 10p: confirmation of regional assignments of platelet-type phosphofructokinase.

A proband, clinically thought to have trisomy 10p, was found to have an inverted duplication of 10p [46, XY, inv dup(10)(qter----p15.3::p15.3----p 11.1:)]. The phenotypic findings and cytogenetic observations were supported by relevant biochemical studies. The activity of phosphofructokinase (platelet-type; PFKP), previously localized to 10p, and hexokinase-I (HKI), putatively on 10p, demonstrated 153% and 149% of control activity in the proband's fibroblasts. These gene-dosage effects confirmed the clinical and cytogenetic observations as well as the localization of HKI to 10p. Additionally, phosphofructokinase (PFK) and hexokinase (HK), which are control points in the glycolytic pathway, were shown to be syntenic.