Article Abstract:
Most patients with 18q- syndrome appear to have a terminal deletion of the long arm of chromosome 18 cytogenetically. A group of 18q- patients were diagnosed by use of standard cytogenetic banding techniques. The banding techniques do not have enough resolution for precise genotyping. DNA from 35 patients who originally were diagnosed as having de novo terminal deletions of chromosome 18 has been analyzed.Of 35 people reported to have terminal deletions of 18q, it was found that 5 have more complex cryptic rearrangements and that 3 have the most distal portion of 18q. That is consistent with an interstitial, not a terminal, deletion. It seems a standard karyotype can lead to inadequate characterization in 18q- syndrome.
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Article Abstract:
Paternal uniparental disomy for chromosome 1 has been shown by use of molecular analysis for a pycnodysostosis (cathepsin K deficiency) patient. Pycnodysostosis is an autosomal recessive skeletal dysplasia. Paternal uniparental disomy with partial isodisomy came from a meiosis II nondisjunction event. This is the first identified case of paternal uniparental disomy of chromosome 1. Conclusive evidence that paternally derived genes on human chromosome 1 are not imprinted has been found.
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Article Abstract:
A single gene or two tightly linked genes on chromosome 18 may account for the relationship between Paget disease of bone and osteosarcoma. A putative tumor-suppressor locus on chromosome 18q has been isolated through analysis of 96 sporadic osteosarcomas for tumor-specific loss of constitutional heterozygosity and localized to a region between D18S60 and D18S42, which is also associated with familial Paget disease.
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