Article Abstract:
Derivative 22 (der (22)) syndrome and velo-cardio-facial syndrome/DiGeorge syndrome have in common a 1.5-Mb region in chromosome 22q11. Der(22) syndrome is rare. It is associated with a number of congenital irregularities including preauricular skin tags or pits, profound mental retardation, and conotruncal heart defects. It may occur in children of carriers of the constitutional t(11;22)(q23;q11) translocation, the result of a 3:1 meiotic malsegregation event that leads to partial trisomy of chromosomes 22 and 11. The trisomic region on chromosome 22 overlaps the region hemizygously missing in another congenital disorder involving anomalies, that is, velo-cardio-facial syndrome/DiGeorge syndrome (VCFS/DGS). Fluorescence in situ hybridization (FISH) mapping and haplotype analysis were carried out for five patients with der(22) syndrome in a project to identify the interval on 22q11 containing the t(11;22) breakpoint.
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Article Abstract:
Molecular cytogenetic evidence exists for a common breakpoint for the largest inverted duplications of chromosome 15 (inv dup (15)). Chromosomes from 20 patients were used in the delineation of the breakpoints of inverted duplications that include the Prader-Willi syndrome/Angelman syndrome (PWS/AS) chromosomal region, 15q11-113. Two types of inv dup(15) have been described, those that break between D15S12 and D15S24 and those that share a breakpoint beside D15S1010. U-type exchange involving particular sequences on either sister chromatids or homologous chromosomes may account for lack of breakpoint heterogeneity. In all cases analyzed, the inv dup(15) came from the maternal side.
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Article Abstract:
Research has shown that mutations in the human sterol delta(super7)-reductase gene at 11q12-13 cause Smith-Lemli-Opitz syndrome (SLOS), known also as RSH syndrome. SLOS is an autosomal recessive multiple malformation syndrome caused by defective cholesterol biosynthesis. Children with the syndrome have high serum 7-dehydrocholesterol (7-DHC) levels and usually low serum cholesterol levels. It was shown that cDNA identified in the research codes for the human sterol delta (super7)-reductase. Mutations in DHCR7 are behind at least some SLOS cases.
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