Down syndrome is caused by trisomy of chromosome 21 and is comprised of a constellation of abnormalities including neuropathological features that closely resemble those characterizing the neurodegeneration of Alzheimer disease. Because cultured cell lines from patients with Alzheimer disease and other neurodegenerations have a hypersensitivity to the lethal effects of DNA-damaging agents, we studied the response of Down syndrome lymphoblastoid lines to the lethal effects of ionizing and ultraviolet radiation. Lines from the four Down syndrome patients were more sensitive to X-rays than lines from 28 normal donors (P = 10(-4)), while survival of the Down syndrome lines after ultraviolet irradiation was not significantly different from normal. This hypersensitivity to X-rays, which may reflect defective repair of X-ray-induced DNA damage, represents the first abnormality common to cultured cells from both Down syndrome and Alzheimer disease patients.

Alzheimer Disease↗

PubMedDate not supplied

No evidence for an association between a variant of the mast cell chymase gene and atopic dermatitis based on case-control and haplotype-relative-risk analyses.

Atopic dermatitis (AD) is a chronic relapsing dermatitis which belongs to the group of atopy-related diseases as well as asthma and allergic rhinitis. As a probable genetic risk which may contribute to the organ specificity of AD, an association between AD and a genetic variant of the gene encoding mast cell chymase (MCC), which has chymotrypsin-like specificity and is abundant in skin mast cells, has been reported in a Japanese population. We tried to confirm the role of this polymorphism in the development of AD in a Japanese population. A case-control analysis using 100 AD patients and 101 controls did not show a significant difference in the frequency of the BB genotype between the patient and control groups (odds ratio 1. 12, p = 0.81). The haplotype relative-risk analysis using 69 patient-parents trios did not suggest an association (chi2 = 0.177, p = 0.92). Thus, we failed to confirm the association between the polymorphism in the MCC gene and AD in the Japanese population.

Adult↗