Isolated trisomy 7q21.2-31.31 resulting from a complex familial rearrangement involving chromosomes 7, 9 and 10

Abstract

BackgroundGenotype-phenotype correlations for chromosomal imbalances are often limited by overlapping effects of partial trisomy and monosomy resulting from unbalanced translocations and by poor resolution of banding analysis for breakpoint designation. Here we report the clinical features of isolated partial trisomy 7q21.2 to 7q31.31 without overlapping phenotypic effects of partial monosomy in an 8 years old girl. The breakpoints of the unbalanced rearranged chromosome 7 could be defined precisely by array-CGH and a further imbalance could be excluded. The breakpoints of the balanced rearranged chromosomes 9 and 10 were identified by microdissection of fluorescence labelled derivative chromosomes 9 and 10.ResultsThe proband's mother showed a complex balanced translocation t(9;10)(p13;q23) with insertion of 7q21.2-31.31 at the translocation breakpoint at 9p13. The daughter inherited the rearranged chromosomes 9 and 10 but the normal chromosome 7 from her mother, resulting in partial trisomy 7q21.2 to 7q31.31. The phenotype of the patient consisted of marked developmental retardation, facial dysmorphism, short stature, strabism, and hyperextensible metacarpophalangeal joints.DiscussionFor better understanding of genotype-phenotype correlation a new classification of 7q duplications which will be based on findings of molecular karyotyping is needed. Therefore, the description of well-defined patients is valuable. This case shows that FISH-microdissection is of great benefit for precise breakpoint designation in balanced rearrangements.

How to narrow down chromosomal breakpoints in small and large derivative chromosomes – a new probe set

“…Chromosomal rearrangements detected in routine banding cytogenetics currently can be characterized easily by fluorescence in situ hybridization (FISH) and/or array-comparative genomic hybridization (aCGH) (Manolakos et al 2010;Weimer et al 2011). Obviously, aCGH provides higher resolutions; however, FISH still has several advantages over the array-based approaches (Tsuchiya et al 2008;Manolakos et al 2010).…”

Pure Interstitial 7q21.3-q 31.1 Duplication: A Rare Segmental Genomic Aneuploidy: Case Report and Review of Cases with Distal and Similar Segment Involved

“…We extended our study examining clinical data of pure distal versus pure interstitial 7q duplication comparing the six cases reported in the literature with those observed in the present child ( Table 2 ). 3 6 10 17 20 22 Analyzing these results, it appears evident that minor nonspecific craniofacial features, intellectual delay, and skeletal impairment with minor frequency were the most representative clinical signs presented both in the group of children with distal and in the present child with interstitial chromosome 7q involvement.…”

“…8 Pavone et al reported a female child with pre-and postnatal growth retardation and complex malformations with microcephaly, lack of cortical thickening, hypoplastic inferior vermis in association with signs of CS as partial sacral agenesis and complete coccygeal agenesis, preintrasacral dermoid, intradural lipoma, ectopic anus, and tethered cord. [19][20][21][22] The child showed a de novo duplication of 7q34-q35 and an 8.8-Mb deletion on 7q36. This sequence includes HLXB9 (CS) gene which in the case report of Pavone et al was not found.…”

A New Multicolor Fluorescence In Situ Hybridization Probe Set Directed Against Human Heterochromatin

“…A detailed characterization of chromosomal rearrangements detected in routine banding cytogenetics can nowadays be done easily by fluorescence in situ hybridization (FISH) and/or array-comparative genomic hybridization (aCGH) (Manolakos et al 2010; Weimer et al 2011). While in aCGH, a higher resolution may be achieved, FISH still has several advantages over the array-based approaches (Manolakos et al 2010).…”