Host genes and dental caries.

With the attention now being given to molecular genetic analysis of cariogenic microorganisms, the role of host genes in influencing susceptibility to caries should not be forgotten. Increasing knowledge in this field will lead to identification of individuals at particular risk of dental decay and will help in planning rational strategies for management and prevention.

Coefficients of relationship by isonymy among oral cancer registrations in Scottish males.

The role of inherited susceptibility to oral cancers was studied by comparing groups of cancer patients and controls in terms of the coefficient of relationship by isonymy (Ri), both within and between Regions of mainland Scotland. Surname distributions for 3658 male cancer cases were derived from the Scottish Cancer Register for the years 1959-85. Control distributions were derived from a total of 32,468 male deaths in Scotland for 1976.

Coefficients of relationship by isonymy among registrations for five common cancers in Scottish males.

Study Objective: The aim was to assess the relative importance of genetic factors in carcinoma of the stomach, colon, rectum, prostate, and bladder in Scottish males.

Design: Cancer cases and controls were compared in terms of the coefficient of relationship by isonymy (Ri).

Setting: Surname distributions for cancer cases were derived from the Scottish Cancer Register for the years 1959-85.

Coefficients of relationship by isonymy among Scottish males with early and late onset cancers.

Studies of certain cancers suggest that early onset cases tend to have a more pronounced hereditary component than late onset cases. We have analysed data from 60,924 Scottish males with cancer of the stomach, colon, rectum, prostate or bladder, using the coefficient of relationship by isonymy to compare patients whose age at registration was below the median with those whose age at registration was equal to or above the median. There was no evidence for greater isonymy in younger patients suggesting that, although known genetically determined cancers may have earlier onset than other cancers at the same site, early age at onset is not widely associated with a familial predisposition to malignancy.

Chronic atrophic oral candidiasis among patients with diabetes mellitus--role of secretor status.

Non-diabetic individuals who are non-secretors of blood group antigens are prone to superficial infections by Candida albicans. In this study, 216 patients with diabetes mellitus who were denture wearers were examined for the presence or absence of denture stomatitis. There was an overall trend for non-secretors to be prone to denture stomatitis compared with secretors.

Genetic approaches in the study of periodontal diseases.

Periodontal diseases are essentially infectious in origin, their outcome depending on interaction between the pathogenic challenge and host response. Host genotype has been implicated in certain of the more unusual forms, but together these account for only a small proportion of periodontal patients. Nevertheless, the genes for these rarer conditions, some of which have already been located and/or cloned, are of considerable importance, since they may ultimately provide clues leading to a better understanding of the whole spectrum of periodontal disease.

Coefficients of relationship by isonymy among the parents of Scottish twins: a test of familial aggregation.

The ability of the coefficient of relationship by isonymy Ri to detect familial aggregation of conditions suspected of being under a degree of genetic control was tested on groups of fathers and mothers of like-sex twins, fathers and mothers of unlike-sex twins, and fathers and mothers of singleton controls born from 1977 to 1981 in Scotland. No statistically significant difference of within-group or between-group Ri was found, either for all surnames or for rare surnames only. However, the overall pattern of results for rare surnames showed a measure of agreement with what is already known of the genetics of twinning.

Dentistry and the new genetics.

As environmental causes of disease become better controlled, so genetic factors assume relatively greater importance. Opportunities to investigate the genetic contribution to disease have increased dramatically through the remarkable technological developments of recent years. These developments have implications for both education and practice in dentistry, just as in any other branch of the biomedical sciences.

Coefficients of relationship by isonymy within and between the regions of Scotland.

The distribution of surnames for births, marriages and deaths in 1976 among residents of the 12 Local Government Regions of Scotland was analyzed in terms of the coefficient of relationship by isonymy, Ri. Differences between sexes and events for Ri within Regions were consistent with greater inter-Region mobility among males compared with females and among young adults compared with the elderly. There were near zero correlations of geographical distance with Ri between Regions based on all surnames or common surnames.

Host genotype, pathogenic challenge and periodontal bone loss in the mouse.

Periodontal bone loss was induced in mice of different genotypes by oral inoculation with Actinomyces viscosus. Relatively high bone loss occurred in the mutant X-linked immune deficiency, implicating the humoral immune system. Maximum bone loss was always associated with inoculations of 1.

Cleft lip with or without cleft palate: identification of sporadic cases with a high level of genetic predisposition.

Previous studies have suggested that asymmetry for certain bilaterally represented features may be an indicator of genetic predisposition to cleft lip with or without cleft palate and may therefore be of value in the individual assessment of recurrence risk, particularly for sporadic cases. An asymmetry score has been devised that may be of use in identifying those with a high level of genetic predisposition. Stepwise logistic regression selected nine variables that together correctly classified 85% of familial cleft patients and unrelated non-cleft controls.

Sweat pore count, hair density and tooth size: heritability and genetic correlation.

In 109 subjects from 50 families without major inherited disorders, sweat pore count showed the anticipated reduction with age but also unexpected systematic differences between sides and between fingers. After adjustment for age and sex, significant genetic variation was found for sweat pore count, hair density and tooth size. The three traits were not phenotypically correlated but there was a significant negative genetic correlation between hair density and sweat pore count.

Difficulties in obtaining a sample of young adult cleft lip and palate subjects and their relatives.

Families of individuals aged 15-24 yr born with cleft lip, with or without cleft palate, and suitable control families were required for a study of inherited predisposition to the malformation. Cleft patients were identified through hospital discharge listings, but the overall yield of participating patients was only 8% of the cases listed. An attempt to recruit control subjects by the same method, using patients who had been hospitalized for dissection tonsillectomy, yielded only 4% of those identified as suitable in the discharge listings.

Affinities between contemporary and skeletal Jewish and non-Jewish groups based on tooth morphology.

Samples from five Jewish and six non-Jewish populations were compared in terms of the frequencies of 19 dental morphological variables. All but one of the samples came from Europe, North Africa, or the Middle East. Nine were from contemporary populations, and two were skeletal.

Heritability estimation from concordant twin pairs alone.

Heritability estimation is possible from concordant twin pairs alone, based on the proportion of like-sexed pairs among all concordant affected pairs. The method is limited to conditions found in both sexes in the prevalence range 0.1% to 10%, and a relatively large population size is required to give an adequate sample of twin pairs.

Developmental stability in the mouse vertebral column.

The effects of six mutant genes (Sd, T, vt, Sp, un, Ph) on the axial skeleton of the mouse were studied both alone and in combination with 24 hours starvation on Day 8 of gestation. Normal controls showed a craniocaudal gradient of size variation and relatively low variability towards the boundaries of the cervical, thoracic and lumbar vertebral classes. Gene-induced craniocaudal gradients of abnormality were observed in response to Sd and T, and to Ph, which have direct and indirect effects respectively on the primitive streak and/or notochord.

Dental extractions in Paget's disease of bone.

The results of a postal questionnaire completed by 360 patients with Paget's disease of bone, on behalf of themselves and their unaffected spouses, suggest that dental practitioners have some awareness of the potential problems associated with extractions for patients with Paget's disease, but that nevertheless patients still suffer from greater difficulty at extraction and more post-extraction complications than normal.

A family study of Paget's disease of bone.

Familial aggregation of Paget's disease of bone occurs occasionally and an exclusively genetic aetiology has been proposed in the past. On the other hand, epidemiological surveys point to an important environmental contribution, and evidence is accumulating to suggest that the disease may be caused by a slow virus infection. Analysis of 407 family history questionnaires completed by patients with Paget's disease confirmed the familial nature of the disease.

Experimental oral infection of mice with a pathogenic and a non-pathogenic strain of the yeast Candida albicans.

Oral infection by Candida albicans is thought to be related more to host susceptibility than to virulence of the organism. Using a mouse model of oral candidosis, differences in colonization and infection between two strains of C. albicans were demonstrated.

Experimental oral infection with the yeast Candida albicans in mice with or without inherited iron-deficiency anaemia (sla).

The role of iron deficiency in the development of oral candidosis was investigated using the mouse mutant sex-linked anaemia (sla). Susceptibility was assessed in terms of the recovery of organisms, particularly from oral swabs, and histological evidence of infection approximately 10 days after the last exposure to Candida albicans. The influence of three factors was studied in mixed groups of normal and anaemic mice: mode of inoculation, treatment with tetracycline and treatment with hydrocortisone.