The developing role of anthropologists in medical genetics: anthropometric assessment of the Prader-Labhart-Willi syndrome as an illustration.
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Biomedical subjects
Publications and source records attributed to F J Meaney.
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The heritability of centrally and peripherally deposited subcutaneous body fat, as measured by thickness of subscapular and triceps skinfolds respectively, was examined in 173 monozygotic and 178 dizygotic pairs of white male twins, ages 54 to 65 years, who participated in the second examination of the National Heart, Lung, and Blood Institute's Twin Study. The heritability of two indices of body fat distribution (subscapular/triceps ratio and subscapular-triceps difference) and two indices of overall obesity (body mass index and sum of skinfolds) were also assessed. Evidence for a genetic influence on central deposition of body fat was suggested in that the classical estimate of heritability for subscapular skinfold thickness was 0.77 (p less than 0.0001). After adjusting subscapular skinfold for the overall level of obesity, heritability was reduced but remained highly significant (0.40, p = 0.003). Heritability estimates for triceps skinfold thickness and for the two fat distribution indices were substantially lower and were not statistically significant after adjustment for overall obesity. High classical estimates of heritability were also observed for both measures of overall obesity: 0.70 for BMI and 0.73 for sum of skinfolds. However, these two estimates were biased upward because of lower total variances among monozygotic compared to dizygotic twins in this sample. The more conservative and unbiased among-component estimates also suggested substantial heritability for each measure (0.35, p = 0.08 and 0.53, p = 0.01, respectively). The heritability of overall obesity emphasizes the importance of adjusting measures of fat distribution for overall obesity before assessing its heritability.
Metacarpophalangeal pattern profile (MCPP) was determined on 34 Sotos syndrome individuals and compared with previous MCPP studies. The mean hand profile contained a major peak in the proximal phalangeal area and a smaller peak in the metacarpal area, while the distal hand bones were relatively short. There appear to be three recognized hand profiles in Sotos syndrome, which suggests heterogeneity of the syndrome, although correlation studies indicate clinical homogeneity of individuals in the younger age groups. Discriminant analysis of Sotos syndrome versus control subjects produced a function of two MCPP variables, plus age, which may be applied as another diagnostic tool.
We analyzed the metacarpophalangeal pattern profile (MCPP) on 18 male individuals from 16 families with fragile X--fra (X), or Martin-Bell--syndrome and calculated a mean syndrome profile. Fourteen of 18 individuals with fra (X) syndrome had significant positive correlations which indicated clinical homogeneity. Discriminant analysis of individuals with fra (X) syndrome compared with a sample of normal individuals produced a correct classification rate of 88% based on a function of 3 MCPP variables that may provide a useful tool in screening individuals for the fra (X) syndrome. Discriminant and correlation analyses of individuals with Sotos sequence and individuals with fra (X) syndrome did not identify MCPP similarities. Therefore, there was no MCPP evidence in our study of patients with Sotos sequence and fra (X) chromosome expression.
In the third decade of newborn screening for phenylketonuria (PKU) and other disorders computers are being used increasingly for both the laboratory and the follow-up aspects of screening programs. In 1984 slightly less than 40% of the state programs had automated follow-up. Lack of funding is probably the major inhibitor of more widespread use of computers in tracking newborns through the newborn screening process. It is suggested that federal funds be made available to ensure wider distribution of currently used tracking systems and development of methods for tracking newborns from birth through follow-up.
We report the first prospective longitudinal study of dietary intake, weight, height, and skinfold measurements during the early phase of four Prader-Labhart-Willi syndrome (PLWS) individuals (two males and two females). Although caloric intake ranged from 80 to 90 percent of recommended daily allowance during our study of the four PLWS infants, obesity still occurred. Our findings suggest that the onset of obesity in PLWS individuals occurs earlier than previously thought in spite of reduced caloric intake. The infants in our study reached the obese range judged by skinfold measurements greater than the 85th centile at an early age and before they were considered heavy based on weight for height criterion. We propose that skinfold measurements should be obtained on all individuals with PLWS and obesity judged by this criterion.
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Weight, height, sitting height, and 24 other anthropometric variables (5 body circumferences, skinfolds at 7 sites, 4 head dimensions, and 8 hand and foot measurements) were obtained on 38 Prader-Labhart-Willi syndrome (PLWS) individuals (21 with apparent chromosome 15 deletions and 17 nondeletion cases) with an age range of 2 weeks to 38 1/2 years. More than half of these individuals were measured on more than one occasion. The measurements confirmed the presence of short stature, small hands and feet, obesity, and narrow bi-frontal diameter in PLWS. No differences were found for the anthropometric measurements between the 2 chromosome subgroups. Inverse correlations were produced with linear measurements (eg, height, hand and foot lengths) and age, which indicated a deceleration of linear growth relative to normal individuals with increasing age.
We analyzed the metacarpophalangeal pattern profile (MCPP) on 15 individuals with Robinow syndrome and calculated a mean Robinow syndrome profile. Correlation studies confirm clinical homogeneity of the hand profile in the Robinow syndrome. Discriminant analysis of individuals with Robinow syndrome compared with a sample of normal individuals produces a function of 6 MCPP variable that may provide a useful tool for diagnosis.
We analyzed the metacarpophalangeal pattern profile (MCPP) on 16 individuals with diastrophic dysplasia and calculated a mean syndrome profile. Correlation studies confirm clinical homogeneity of the hand profile in diastrophic dysplasia. Discriminant analysis of individuals with diastrophic dysplasia compared with a sample of normal individuals produced a function of 3 MCPP variables plus age that appears to be a useful diagnostic tool.
A study of anthropometric variation and craniofacial growth in individuals with the Prader-Labhart-Willi syndrome (PLWS) illustrates the utility of anthropometry in clinical evaluation and research. Anthropometric measurements, including head length and breadth, minimum frontal diameter, and head circumference, were obtained on 38 PLWS individuals (21 with chromosome 15 deletions) with an age range from 2 weeks to 39 years. No anthropometric differences were found between the two chromosome subgroups. A relative deceleration in the growth of certain craniofacial dimensions (head circumference and length) is suggested by the negative correlations between age and Z-scores for the measurements. Raw values for minimum frontal diameter and head breadth were near or below the 5th percentile curve, while almost all values for head length and circumference fell within normal limits. The data support suggestions that dolichocephaly be considered an early diagnostic feature of PLWS. Furthermore, the status of narrow bifrontal diameter as a major feature of PLWS is confirmed.
Computer-based systems for the management of data in clinical genetics have become increasingly available for patient information storage and retrieval, evaluation and diagnosis, and pedigree data. The need for a national genetic services database has been recognized, and federal grants have provided funds for the development of state and regional databases for the evaluation of genetic services. Continuation of federal funding and the development of data systems that allow local, state, and regional needs to be met are essential for any progress to be made toward a national database.
In a clinical and cytogenetic survey of 39 individuals with Prader-Labhart-Willi syndrome (PLWS) (23 males and 16 females ranging in age from 2 weeks to 39 years), an interstitial deletion of chromosome 15 (breakpoints q11 and q13) was identified in 21 cases and apparently normal chromosomes in the remainder. Studies of parental chromosome 15 variants showed that the del[15q] was paternal in origin, although chromosomes of both parents were normal. All chromosome deletions were de novo events. Possible causes for the chromosome deletion and the role of chromosome rearrangements in individuals with PLWS are discussed. Clinical characteristics of the deletion and nondeletion groups were recorded and compared with 124 individuals reported in the literature. Individuals with the chromosome deletion were found to have lighter hair, eye, and skin color, greater sun sensitivity, and higher intelligence scores than individuals with normal chromosomes. Correlation studies of metacarpophalangeal pattern profile variables and dermatoglyphic findings indicate apparent homogeneity of the deletion group and heterogeneity of individuals with PLWS and normal chromosomes.
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Anthropometry has become an important tool in the study of genetic conditions, particularly as a diagnostic aid for the clinical geneticist. However, many practicing physicians do not do anthropometry of patients for several reasons, such as: appropriate measurements in a given situation are unknown; normative reference data are unavailable; or analysis and interpretation of the data are confusing. In this review we present an annotated compilation of informative measurements for hereditary and congenital disorders and a guide to normative anthropometric data of use in evaluation and diagnosis of such disorders. Further development of multivariate approaches will enhance the application of anthropometry as a means of identifying and classifying a syndrome and documenting the natural history of many disorders. Continued cooperation among physicians, geneticists, and anthropologists for the collection and assessment of patient and normative data is essential if these goals are to be realized.
The hand is a complex anatomical structure with the component bones susceptible to a combination of environmental and genetic factors that may affect the bone length and width. The alterations may involve a single bone or specific group of bones. The metacarpophalangeal pattern profile (MCPP) developed by Poznanski, Garn, and others (Poznanski et al. Birth Defects VIII (5): 125-131, 1972) is a graphic representation of the relative lengthening and shortening of the 19 tubular bones of the hand useful for diagnosis, comparison of dissimilar patients, and gene carrier detection. The profile hand bone measurements are derived from posteroanterior hand radiographs and are standardized for age and sex. Specific profiles have been developed for several syndromes. Therefore, MCPP analysis has developed from a method of describing changes in the hand to a technique useful in assigning a diagnosis to a specific syndrome and evaluation of skeletal development. The current status of MCPP analysis in clinical genetics, particularly with the Prader-Labhart-Willi and Sotos syndromes, is discussed.
The metacarpophalangeal pattern profile (MCPP) was analyzed on 16 Sotos syndrome patients. A mean Sotos syndrome profile was produced. Correlation studies confirm clinical homogeneity of Sotos syndrome individuals. Discriminant analysis of Sotos syndrome patients and normal individuals produces a function of two MCPP variables and age, which may provide a useful tool for diagnosis.
An anthropometric investigation was designed to evaluate patterns of physical deterioration in Huntington's disease (HD). In this study a comprehensive set of measurements was taken including height, weight, body circumferences, skinfold thickness, and craniofacial, linear, and breadth components of the body, on 44 normal, 26 affected, and 70 at-risk individuals between 14 and 88 years of age. The anthropometric data were converted to z-scores using standards to adjust for age and sex differences. These scores were then adjusted for inter-family variation. There were significant differences among normal and affected individuals for all dimensions of body mass, as well as for several craniofacial and linear components of the body. Several significant differences were also found between normals and particular age cohorts of at-risk persons. HD gene carrier status was further assessed by factor analysis of the adjusted scores.