Biomedical subjects
Publications and source records attributed to M Swift.
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A simple method for recovery of Bordetella pertussis is described using phosphate-buffered saline containing a casein hydrolysate for transporting secretions collected by nasopharyngeal aspirate. Bordetella pertussis was reisolated from 92% of clinical specimens held at 4 degrees C for 1 week and from all specimens held at -20 degrees C. This method will facilitate the centralization of laboratory facilities for the diagnosis of pertussis.
Sib-pair linkage analysis has been proposed for identifying genes that predispose to common diseases. We have shown that the presence of assortative mating and multiple disease-susceptibility loci (genetic heterogeneity) can increase the required sample size for affected-affected sib pairs several fold over the sample size required under random mating. We propose a new test statistic based on sib trios composed of either one unaffected and two affected siblings or one affected and two unaffected siblings. The sample-size requirements under assortative mating and multiple disease loci for these sib-trio statistics are much smaller, under most conditions, than the corresponding sample sizes for sib pairs. Study designs based on data from sib trios with one or two affected members are recommended whenever assortative mating and genetic heterogeneity are suspected.
BACKGROUND: Ataxia-telangiectasia is an autosomal recessive syndrome in which cancers develop in affected homozygotes at a rate approximately 100 times higher than in unaffected age-matched subjects. Retrospective studies have shown that persons heterozygous for the ataxia-telangiectasia gene, who make up about 1 percent of the general population, also have an excess risk of cancer, particularly breast cancer in women. Patients with ataxia-telangiectasia and cells derived from homozygotes and heterozygotes are unusually sensitive to ionizing radiation. METHODS: Cancer incidence and mortality, mortality from ischemic heart disease, and mortality from all causes were compared prospectively for a mean of 6.4 years in 1599 adult blood relatives of patients with ataxia-telangiectasia and 821 of their spouses, who served as controls, in 161 families affected by ataxia-telangiectasia. In a case-control substudy, we compared documented occupational and fluoroscopic diagnostic exposures to radiation in the 19 female blood relatives in whom breast cancer was first diagnosed during the period of prospective observation with the exposures in 57 matched blood relatives who did not have breast cancer. RESULTS: Cancer rates were significantly higher in the group of blood relatives than in their spouses, specifically in the subgroup of 294 blood relatives who were known to be heterozygous for the ataxia-telangiectasia gene. The estimated risk of cancer of all types among heterozygotes as compared with noncarriers was 3.8 in men and 3.5 in women, and that for breast cancer in women was 5.1. Among the blood relatives, women with breast cancer were more likely to have been exposed to selected sources of ionizing radiation than controls without cancer (odds ratio = 5.8, P = 0.005). Male and female blood relatives also had 3-fold and 2.6-fold excess mortality from all causes, respectively, from the ages of 20 through 59 years. CONCLUSIONS: The ataxia-telangiectasia gene predisposes heterozygotes to cancer, particularly breast cancer in women. There is also excess mortality from all causes in adults under the age of 60. Diagnostic or occupational exposure to ionizing radiation probably increases the risk of breast cancer in women heterozygous for ataxia-telangiectasia.
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Ataxia-telangiectasia is a genetic syndrome with progressive cerebellar ataxia, oculocutaneous telangiectasias and other skin manifestations, variable immune system defects, chronic progressive sinopulmonary disease, and a high incidence of cancer. Cutaneous granulomas developed and persisted in eight patients with ataxia-telangiectasia, despite treatment with intravenously administered immune globulin, topical antibiotic therapy, and potent topical corticosteroid therapy. We were unable to identify an infectious agent; the granulomas may develop in an attempt to localize antigen in the presence of a dysfunctional immune system.
OBJECTIVE: The purpose of this study was to test the hypothesis that heterozygous carriers of the gene for the Wolfram syndrome, who constitute about 1% of the population, are predisposed to significant psychiatric illness. The Wolfram syndrome is an autosomal recessive neurodegenerative syndrome in which 25% of the individuals who are homozygous for the condition have severe psychiatric symptoms that lead to suicide attempts or psychiatric hospitalizations. METHOD: The authors collected questionnaires, death certificates, and hospital records for blood relatives and their spouses in 36 families of individuals with the Wolfram syndrome and compared the proportion of blood relatives who had had psychiatric hospitalizations, had committed suicide, or had self-reported mental illness to the proportion of spouses with the same manifestations. RESULTS: The proportion of blood relatives who had had psychiatric hospitalizations, had committed suicide, or had self-reported mental illness significantly exceeded the proportion of spouses with the same manifestations. CONCLUSIONS: Since heterozygous carriers of the gene for the Wolfram syndrome are 50-fold more common among the blood relatives than among the spouses, the larger proportion among blood relatives is evidence that heterozygous carriers of the gene for the Wolfram syndrome are predisposed to significant psychiatric illness.
Cancer incidence was measured retrospectively in 574 close blood relatives of white ataxia-telangiectasia (A-T) patients and 213 spouse controls in 44 previously unreported families. The cancer incidence rate in the adult blood relatives was significantly elevated over the rate in the spouse controls (rate ratio = 3.9, p less than 0.01). For heterozygous carriers of the A-T gene, the relative risk of cancer was estimated to be 6.1 (p less than 0.005) as compared with nonheterozygotes. The most frequent cancer site in the blood relatives was the female breast, with nine cancers observed. These findings provide further support for the hypothesis that heterozygotes for the A-T gene are predisposed to cancer.
Diabetes mellitus and bilateral optic atrophy are the defining characteristics of the autosomal recessive Wolfram syndrome. Diabetes insipidus, neurogenic bladder, deafness, and other neurological manifestations are frequent. A review was made of the medical records of 68 Wolfram syndrome patients, aged between 8 and 43 years, identified by casefinding throughout the USA. 41 of the patients (60%) had episodes of severe depression, psychosis, or organic brain syndrome, as well as impulsive verbal and physical aggression. These symptoms were very severe in 17 patients (25%), of whom 12 required admission to a psychiatric hospital and 11 attempted suicide. We conclude that the Wolfram syndrome gene predisposes homozygotes to psychiatric illness.
The Bardet-Biedl syndrome is a rare autosomal recessive disorder characterized by pigmentary retinopathy, obesity, polydactyly, hypogonadism, and mental retardation. Renal abnormalities, hypertension, acquired heart disease, and hepatic fibrosis also occur in homozygotes. Two adult Bardet-Biedl sibs, a man with hypertension and cardiomegaly and a woman with biliary cirrhosis, and 75 relatives in 5 generations of the extended family were identified. Hospital records for major illnesses, death certificates, and autopsy reports were examined. The frequent observation of obesity, hypertension, diabetes mellitus, and renal disease in first-degree relatives, obligate gene carriers, and other blood relatives raise the possibility that Bardet-Biedl heterozygotes are also predisposed to these disorders.
Ataxia-telangiectasia (A-T) is a progressive neurologic disorder in which there is varied immune dysfunction, an excess sensitivity to ionizing radiation, and a striking predisposition to cancer. It is the autosomal recessive syndrome for which there is the strongest evidence, derived from retrospective studies of cancer incidence and mortality in A-T families, that the heterozygote is predisposed to cancer. We present, in tabular form, the specific cancer sites or types most likely to be associated with A-T heterozygosity. These include solid tumors of the breast, pancreas, stomach, bladder, and ovary, and chronic lymphocytic leukemia. We also introduce a new method to test these associations. As soon as molecular probes for the A-T allele(s) are available, this new research design will be used to test rigorously each association, hypothesized on the basis of previous data, between a specific cancer site and A-T heterozygosity.
Ataxia-telangiectasia (A-T) is an autosomal recessive syndrome whose principal features are progressive cerebellar ataxia, oculocutaneous telangiectasia, varied immune defects, a high cancer incidence, and clinical and cellular sensitivity to ionizing radiation and certain radiomimetic compounds. Cell and chromosome complementation studies have provided some evidence that mutations leading to the A-T phenotype may have occurred at more than one locus. Mapping with DNA polymorphisms has localized the predominant A-T mutation to chromosome 11q22-23. Heterozygous carriers of an A-T allele constitute about 1% of the United States population and are at a high risk for certain cancers, most notably female breast cancer. Cloning of the A-T allele(s) will assist in the early or prenatal diagnosis of A-T and provide a firm basis for determining who, in the general population, carries this gene and is therefore at a high risk of cancer.
We propose a method for testing any hypothesized association between a candidate allele, for which there is a specific laboratory test, and a common chronic disease. Families in which this allele is segregating are identified through index individuals who are homozygous or heterozygous for the allele. The sample consists of the subset of identified families who also have at least one member with the common disease of interest. For each independent family in this subset, select one person with the disease and determine if he or she is heterozygous for the allele. The observed proportion of heterozygotes in this sample is compared to the proportion expected on the basis of each diseased relative's null probability of being heterozygous for the allele; this null probability depends only on the relative's relationship to the index individual and the population allele frequency. We provide these null probabilities, develop appropriate inference procedures, discuss sample size requirements, and compare this method to a standard case-control design. Results using this method are unlikely to be influenced by confounders, systematic bias, or genetic heterogeneity.
In a sibship of 11, two brothers with a congenital complete horizontal gaze palsy developed severe kyphoscoliosis. No-one else in the family has a gaze palsy or comparable skeletal abnormalities. Since the parents are first cousins, an autosomal recessive mode of inheritance seems likely.
In 31 families of xeroderma pigmentosum (XP) patients, significantly more blood relatives than spouse controls had had nonmelanoma skin cancer. These family data support the hypothesis that heterozygosity for XP genes may predispose persons to skin cancer, particularly in association with substantial exposure to sunlight.
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White individuals who are HLA B27-positive have an increased risk of developing ankylosing spondylitis or related diseases. HLA typing can be used in counseling relatives of persons with spondylitis, if the limitations of presently available data are recognized.
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