A model for analyzing heritability in the presence of correlated genetic and environmental effects

The purpose of this paper is to point out some of the problems that may arise when the conventional genetic model is applied and there are correlated genetic and environmental effects and to indicate a possible solution to the problems raised.     

Exclusion testing in pregnancy for Huntington''s disease.

The results of DNA analysis are presented for a series of 90 couples, with one partner at 50% risk for Huntington's disease (HD), who were referred for exclusion testing in pregnancy over a three year period. Thirty-seven couples were studied in detail. The aims of the study were to evaluate attitudes towards prenatal testing, before pregnancy and afterwards, and the effectiveness of our counseling and methods of organising the service. Problems which could arise in relation to presymptomatic testing are documented. It is concluded that exclusion testing is a valuable form of prediction for some couples, particularly where family structure does not permit prediction for the person at risk. The need for intensive counselling was highlighted by the difficulties experienced by many couples in understanding how the test worked. Particular ethical and organisational problems may arise which require careful consideration beforehand and some recommendations are made. The proportion of couples who will continue to request exclusion testing as pre-symptomatic testing becomes more widely applicable remains unknown.     

Mutation analysis of 184 cystic fibrosis families in Wales.

We describe a molecular analysis of 184 cystic fibrosis (CF) families in Wales. To determine accurate frequency data for the CF mutations in the Welsh population, families with at least three Welsh grandparents were strictly regarded as Welsh. Of these 74 families, we have identified approximately 90% of mutations causing CF, with delta F508 accounting for 71.8% and 621 + 1G greater than T 6.7%. We observed a significant difference between the Welsh and Scottish frequencies of 621 + 1G greater than T. To allow the rapid and efficient screening for the more common mutations we modified a multiplex used by Watson et al enabling the detection of delta F508, G551D, and R553X simultaneously with 621 + 1G greater than T. In parallel to this system we ran the Cellmark Diagnostics ARMS multiplex kit, which detects delta F508, 621 + 1G greater than T, G551D, and G542X. RFLP analysis of the 184 families shows that the delta F508 chromosomes are almost exclusively found on the B haplotype (XV2c 1, KM19 2); the other CF mutations have more heterogeneous backgrounds. Strong haplotype correlations exist between the markers XV2c, KM19, D9, and G2 and the other CF mutations. Haplotype data suggest that there are at least seven mutations that remain to be identified in these families.     

Hereditary influence on the normal personality using the MMPI. I. Age-corrected parent-offspring resemblances

The MMPI was administered to 28 adolescent offspring from marriages in which both parents had taken the test during the ninth grade. Therefore, parent-offspring comparisons could be made on these measures of personality obtained at approximately the same age, one generation apart. Thus age bias is eliminated. Correlations and regressions for the ten clinical scales and K validity scale were determined. Heritability estimates were computed including corrections for parental assortative mating. The heritability estimates for the psychotic scales (6-Pa, 7-Pt, 8-Sc, and 9-Ma) tended to be higher than those for the remaining test scales.This study was supported by NIH grant MH-10679.     

The infrapyloric artery and cephalic pancreatoduodenectomy with pylorus preservation: preliminary study

Summary Cephalic pancreatoduodenectomy (CPD) with pylorus preservation has been suggested to improve the functional and nutritional result of surgery. At operation, the first two centimeters of the duodenum are preserved, the vascular arch of the lesser gastric curvature is saved and the right gastroepiploic artery is resected at its origin. The aim of this study on 15 fresh cadavers was to determine the origin of the vascularization of the remaining duodenum and also the possibilities of preserving an optimal vascularization after CPD and pylorus preservation. All of the arteries supplying the remaining duodenum and arising either from the right gastric artery or the right gastroepiploic artery were identified. The distances between the origin of the infrapyloric artery and the termination of the gastroduodenal artery on the cranial and ventral pancreaticoduodenal artery and the left gastroepiploic artery were measured. At CPD with pylorus preservation, the study demonstrated that: 1) the cranial side of the remaining duodenum remains vascularized in 80% of the cases by one or two supraduodenal branches coming from the right gastric artery; 2) ligation of the right gastroepiploic artery eliminates all vascular supply to the caudal side of the remaining duodenum in almost half of the cases; 3) in these cases, the dissection of the bifurcation of the gastroduodenal artery and the vascular section beyond the origin of the infrapyloric artery allowed a direct vascular supply to the remaining duodenum to be preserved.This work was presented at the French Section of the European Association of Clinical Anatomy meeting, Bobigny, France, 1992     

Long-term effects of infant rearing condition on the acquisition of dominance rank in juvenile and adult rhesus macaques (Macaca mulatta)

We examined the effects of early rearing experience on the development of dominance status in 53 juvenile (age 3) and then in 38 adult (ages 5-8) rhesus macaques. Based on previous research investigating the behavioral outcomes of nursery-rearing, we predicted that mother-reared (MR) monkeys would outrank peer-only reared (PR) monkeys, which would in turn outrank surrogate/peer-reared (SPR) subjects. Juvenile MR and PR subjects did not differ in ranks, but monkeys from both rearing backgrounds outranked SPR cage-mates at age 3. Independent of rearing condition, high-ranking juveniles gained the most weight between ages 1-3, suggesting that low status may be associated with decreases in early weight gain. Adult MR subjects outranked both PR and SPR subjects, with PR animals occupying intermediate ranks. These results indicate that impoverished early experiences, such as adult absence and limited social interaction, are useful predictors of future social success in rhesus macaques.     

Missense mutation in a von Willebrand factor type A domain of the alpha 3(VI) collagen gene (COL6A3) in a family with Bethlem myopathy

The Bethlem myopathy is a rare autosomal dominant proximal myopathy characterized by early childhood onset and joint contractures. Evidence for linkage and genetic heterogeneity has been established, with the majority of families linked to 21q22.3 and one large family linked to 2q37, implicating the three type VI collagen subunit genes, COL6A1 (chromosome 21), COL6A2 (chromosome 21) and COL6A3 (chromosome 2) as candidate genes. Mutations of the invariant glycine residues in the triple-helical domain-coding region of COL6A1 and COL6A2 have been reported previously in the chromosome 21-linked families. We report here the identification of a G-->A mutation in the N-terminal globular domain-coding region of COL6A3 in a large American pedigree (19 affected, 12 unaffected), leading to the substitution of glycine by glutamic acid in the N2 motif, which is homologous to the type A domains of the von Willebrand factor. This mutation segregated to all affected family members, to no unaffected family members, and was not identified in 338 unrelated Caucasian control chromosomes. Thus mutations in either the triple-helical domain or the globular domain of type VI collagen appear to cause Bethlem myopathy.      

doublecortin is the major gene causing X-linked subcortical laminar heterotopia (SCLH)

Subcortical laminar heterotopia (SCLH), or 'double cortex', is a cortical dysgenesis disorder associated with a defect in neuronal migration. Clinical manifestations are epilepsy and mental retardation. This disorder, which mainly affects females, can be inherited in a single pedigree with lissencephaly, a more severe disease which affects the male individuals. This clinical entity has been described as X- SCLH/LIS syndrome. Recently we have demonstrated that the doublecortin gene, which is localized on the X chromosome, is implicated in this disorder. We have now performed a systematic mutation analysis of doublecortin in 11 unrelated females with SCLH (one familial and 10 sporadic cases) and have identified mutations in 10/11 cases. The sequence differences include nonsense, splice site and missense mutations and these were found throughout the gene. These results provide strong evidence that loss of function of doublecortin is the major cause of SCLH. The absence of phenotype-genotype correlations suggests that X-inactivation patterns of neuronal precursor cells are likely to contribute to the variable clinical severity of this disorder in females.