Walter E. Nance

Genetic Factors in Determining Bone Mass

This investigation was undertaken to evaluate possible genetic determinants of bone mass with the premise that inheritance of bone mass could be of etiologic importance in osteoporosis. Bone mass and width measurements were made with the photon absorption technique on the right radius of 71 juvenile and 80 adult twin paris. The variance of intrapair differences of bone mass in monozygotic (MZ) juvenile twins was 0.0013 g(2)/cm(2) compared to 0.0052 g(2)/cm(2) in the dizygotic (DZ) twins. For the adult twins the variance of intrapair differences in bone mass was 0.0069 for MZ and 0.0137 for DZ twins. Similar results were obtained for bone width. The significantly larger variation in intrapair differences in DZ twins indicates that these traits have significant genetic determinants. These intrapair differences were found to increase with age, suggesting that genetic-environmental interaction also contributes to the observed variation in bone mass. These data provide evidence that bone mass does have significant genetic factors, which alone or in conjunction with environmental factors may predispose persons to the development of osteoporosis.

Familial branchio-oto-renal dysplasia: a new addition to the branchial arch syndromes.

The present report concerns a two‐generation family of nine individuals in which the father and three of the six living children all had: (1) a mixed hearing loss with a Mondini type cochlear malformation and stapes fixation; (2) cup‐shaped, anteverted pinnae with bilateral prehelical pits; (3) bilateral branchial cleft fistulas; and (4) bilateral renal dysplasia and anomalies of the collecting system. The father and one affected son also had aplasia of the lacrimal ducts. A fourth child who died at 5 months of age was reported to have branchial cleft fistulas and bilateral polycystic kidneys at autopsy. In addition, the concept of noso‐embryologic communities is presented. Such groups are composed of syndromes whose total phenotypic spectra not only overlap but also share common elements in embryogenesis. This concept is illustrated with a group of branchial arch syndromes that are related in this way.

Genetic determinants of cranio-facial morphology: a twin study

The use of twin studies in the analysis of cranio-facial measurements has provided a better understanding of the relative significance of hereditary and environmental factors in the determination of these traits. The ratio of intrapair variances of dizygotic (DZ) and monozygotic (MZ) twins has frequently been used to detect the significant hereditary influences on each trait by univariate statistical procedure. Although this method has resulted in considerable advances in knowledge, little is known about the basic determinants of interrelations among parts of the cranio-facial skeleton from a genetical point of view. Kempthorne & Osborne (1961) described a method for analysing the pairwise interrelationships of multiple variables in twin data. More recently, Vandenberg (1965 a, b ) and Bock & Vandenberg (1968) introduced a new technique of multivariate analysis of interrelated traits in twins. The technique searches for correlations among intrapair differences in twins that are influenced by common genetic factors. For example, to the extent that an observed correlation in intrapair differences in intelligence and height was greater in dizygotic than in monozygotic twins, one might postulate a common genetic influence on the two variables. In this manner, a large number of variables can be grouped into sets of interrelated traits that are influenced by independent genetic factors. An application of this method to multiple anthropological measurements based on roentgenographic cephalograms will be shown and discussed in connexion with previous studies of craniofacial morphology by multivariate analysis.

The use of genetic data in the prediction of craniofacial dimensions

Abstract The genetic determinants of human craniofacial structures have been investigated in a pilot study of twenty-four sets of monozygotic (MZ) twins, twenty-one sets of like-sexed dizygotic (DZ) twins, nineteen sets of unlike-sexed DZ twins, and 103 parents of these subjects. Six linear and two angular measurements were obtained from roentgenographic cephalograms, and age, sex, and stature were included as additional variables. Significant F ratios between intra-pair variances of MZ and like-sexed DZ twins and midparent and offspring correlations were obtained as a whole, a fact that suggests considerable genetic determination of craniofacial structures. The utilization of measurements on relatives for the prediction of craniofacial dimensions was surveyed on the basis of the results of the present investigation.

Genetic Analysis of Dermatoglyphic Patterns in Twins

Analysis of variance was performed on 71 dermatoglyphic variables in 424 twin sets. Using a method of twin analysis estimates of genetic variance were obtained. 54 of the variables were quantitated using a scoring system with modifications of arch or no pattern = 0, loops = 1, whorl = 2. The results indicated a significant genetic influence in most pattern areas. Patterning was more genetically controlled in the hand than in the foot. The hallucal area had the most significant genetic component of the foot while the patterns in the thumb had nonsignificant components of genetic variance. The thumb deviated from patterning in the rest of the fingers and may be more closely related to big-toe patterning.

Linkage Relations of the Loci for Kell and Phenylthiocarbamide Taste Sensitivity

Linkage analysis of Kell:PTC loci demonstration close linkage, theta = 0.045 with a lod score of 10.78. The results, which include the Sutter blood group, support the hypothesis that Sutter is a part of the Kell system.

Genetic Determination of Phenotypic Variation in Sickle Cell Trait

Two genetic sources of variation influence the percentage of sickle cell hemoglobin found in heterozygotes. One factor is strongly related to the percentage of hemoglobin S in the carrier parent and appears to be determined by sickle hemoglobin isoalleles, whereas the other is related to racial background and may well be polygenic.

Genetic Studies of the Offspring of Identical Twins: A Model for the Analysis of Quantitative Inheritance in Man

In conjunction with full-sib and parental observations, half-sib analysis permits an estimation of the genetic and environmental variance as well as a partitioning of the genetic variance into its additive, dominance and epistatic components. The offspring of identical twins are a unique class of human half-sibs who provide an unusual opportunity to resolve and measure several additional potentially important sources of human variation including maternal effects, the influences of common environmental factors and assortative mating. The genetic model thus developed for the analysis of quantitative inheritance in man has been applied to the analysis of total ridge count and birth weight, confirming the existence of a major additive genetic effect on ridge count and a significant maternal effect on birth weight.

Vitiligo and dysgammaglobulinemia. A case report and family study

This report concerns an 8 year old female with vitiligo and a dysgammaglobulinemia characterized by absent IgA, very low IgG, and normal TgM. The t‐cell immune system was intact but other family members had low levels or absence of IgA. The possible relationship of dysgammaglobulinemia and vitiligo is discussed along with the classification and inheritance of the immune cell defects.

Status and Prospects of Research in Hereditary Deafness

The interaction of literally hundreds—perhaps thousands—of genes is required for the development of a normal human ear. Consequently, defects in any one of a great many genes can lead to hearing loss. The recognition that hereditary deafness is not a single disease but a collection of distinct genetic disorders which have one symptom in common is one of the most important insights that have been gained from contemporary genetic research. Mutant genes have always been an important cause of hearing impairment, but with the progressive identification and control of environmental causes of hearing loss, hereditary factors will doubtless account for an even greater proportion of the deaf population in the future. Our intent here is to provide a common body of genetic knowledge for the array of professional groups—including geneticists, audiologists, otolaryngologists, pediatricians, social workers, and educators—who provide services for the hearing-impaired. We believe that, if further progress is to be made in the prevention, treatment, and education of the deaf, it will have to come about through a more widespread recognition of hereditary deafness syndromes and the special problems each presents.