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At least 199 records · Page 11Linked to original sources
PubMed1993

Novel patterns of inheritance of genetic disease are illustrated by the Angelman syndrome.

OBJECTIVE: To characterise the molecular abnormalities present in a cohort of patients with the Angelman syndrome. METHODS: DNA samples from 10 patients with the Angelman syndrome were investigated with molecular probes. Family studies were performed by means of DNA polymorphism analysis and densitometric estimation of allele copy number to determine the underlying mutation and its parental origin. RESULTS: Nine probands were shown to have molecular (DNA) deletions involving chromosome 15q11-q13. Polymorphism analyses demonstrated that all deletions were maternal in origin. Five of the nine had normal karyotypes, with deletions only detected after DNA study. One patient had inherited both chromosomes 15 from her father. This represented an example of paternal uniparental disomy of chromosome 15. CONCLUSIONS: Development of the Angelman syndrome can result from either deletion of the maternally-derived copy of chromosome 15q11-q13 or the presence of two paternally derived copies of chromosome 15, that is, uniparental disomy. DNA testing allows the identification of deletions that are not seen on cytogenetic analysis and can provide additional information regarding the parental origin of the deletion. Uniparental disomy is most readily established by DNA studies.

Adolescent↗
PubMed1996

Evidence for two patterns of inheritance of sensitivity to induction of lung fibrosis in mice by radiation, one of which involves two genes.

We showed previously that autosomal recessive determinants control the development of pulmonary fibrosis in mice during the early and late phases after irradiation. The extent of fibrosis was inversely correlated with the intrinsic lung activity of both plasminogen activator (PLA) and angiotensin-converting enzyme (ACE). To test these observations further, two groups of mice were given a dose of 15 Gy to the thorax: offspring of a backcross between C57L/J ("fibrosing mice") and the F1 of CBA/J ("non-fibrosing in the early phase") x C57L/J, and additional F1 individuals of CBA/J x C57L/J. Mice were euthanized upon developing a substantial respiratory deficiency (50% reduction in carbon monoxide uptake) during the early phase (14-25 weeks postirradiation). Seventeen mice from the backcross were heavily fibrosed, 38 were classed as intermediate, and 15 contained no fibrosis. No evidence of sex linkage was seen. These data strongly support our earlier conclusions and suggest that two autosomal genes which function additively determine the extent of the principal type of fibrosis in these strains. As no indication of a bimodal distribution of lung PLA or ACE activity was obtained, it is unlikely that one of the genes controls the level of either enzyme. The F1 mice unexpectedly showed small amounts of an unusual type of fibrosis which was not associated with hyaline material or fibrin deposits, in contrast to all previous reports of fibrosis during the early phase in mice. Similar, fibrin-free fibrosis was found during the early phase in mast cell-deficient WBB6F1/J mice (and their normal siblings). In the F1 mice this unusual fibrosis appears to be regulated independently by two additional genes, one of which is sex-linked.

Animals↗
PubMedDate not supplied

Patterns of inheritance in Irish and Italian families with neural tube defects: comparison between high and low rate areas.

Neural tube defects (NTDs) may result from a genetic susceptibility interacting with environmental exposures occurring early in pregnancy. Current research is concerned with enlarging our understanding of the action of folic acid, a B group vitamin, which has been shown to prevent the occurrence of NTDs in clinical trials. Despite the epidemic waves in the incidence of NTDs and the existence of areas with very high rates, there have been few studies that explored the genetic contribution to NTDs in high rates versus low rate areas. We investigated the genetic epidemiologic factors that occur in NTD families and compared their frequency in a high rate area-Ireland-with a low rate area-Italy. We explored the existence of three features indicative of hereditary factors and found that all three factors were higher in Ireland than in Italy. These factors were (i) sibling recurrence risk (3.3% vs 1.6%; p = 0.2), (ii), other malformations in siblings (11.5% vs 3.3%; p < 0.001) and (iii) average number of children in mothers' families vs fathers' families (average difference in Ireland 1.0 vs 0.4 in Italy; p < 0.1). These results support the motion that geographic differences in occurrence of NTDs are due at least in part to differing prevalences of genetic susceptibility factors. Further epidemiological and molecular studies are needed to confirm this observation. In addition, studies of the interactions between environmental agents and genetic susceptibility will be important in determining their relative contributions.

Child↗
PubMed1998

Mitochondrial A7445G mutation in two pedigrees with palmoplantar keratoderma and deafness.

A New Zealand and a Scottish pedigree with maternally inherited sensorineural deafness were both previously shown to carry a heteroplasmic A7445G mutation in the mitochondrial genome. More detailed clinical examination of the New Zealand family showed that the hearing loss was progressive, with the severity of the overall loss and the frequencies most affected differing markedly between individuals of similar age, and showed that many relatives also had palmoplantar keratoderma. Review of the literature demonstrated three other large families with presumed autosomal dominant inheritance of palmoplantar keratoderma and hearing loss. In a United Kingdom pedigree the syndrome was transmitted by female and male parents, an inheritance pattern which made mitochondrial inheritance unlikely; however, in a Turkish and a Japanese pedigree the affected individuals were all maternally related. Subsequent analysis of the Japanese pedigree documented the same A7445G mitochondrial mutation as was previously found in the New Zealand and Scottish pedigrees. Other mitochondrial sequence variants previously reported in the New Zealand or Scottish pedigrees were absent from the Japanese pedigree which suggests that the A7445G mutation arose independently in all three pedigrees. To our knowledge palmoplantar keratoderma has not previously been associated with mitochondrial defects; however, the current findings suggest that the A7445G mutation is associated not only with progressive hearing loss but also with palmoplantar keratoderma. The penetrance and expressivity of both symptoms varied considerably between individuals in the Scottish and New Zealand Studies which suggests that additional environmental and/or genetic factors are involved.

Adolescent↗
PubMed1998

Genetic analysis of male pattern baldness and the 5alpha-reductase genes.

Genetic predisposition and androgen dependence are important characteristics of the common patterned loss of scalp hair known as male pattern baldness. The involvement of the 5alpha-reductase enzyme in male pattern baldness has been postulated due to its role in the metabolism of testosterone to dihydrotestosterone. There are two known isozymes of 5alpha-reductase. Type I has been predominantly localized to the skin and scalp. Type II, also present on the scalp, is the target of finasteride, a promising treatment for male pattern baldness. We conducted genetic association studies of the 5alpha-reductase enzyme genes (SRD5A1 on chromosome 5 and SRD5A2 on chromosome 2) using dimorphic intragenic restriction fragment length polymorphisms. From a population survey of 828 healthy families comprising 3000 individuals, we identified 58 young bald men (aged 18-30 y) and 114 older nonbald men (aged 50-70 y) for a case control comparison. No significant differences were found between cases and controls in allele, genotype, or haplotype frequencies for restriction fragment length polymorphisms of either gene. These findings suggest that the genes encoding the two 5alpha-reductase isoenzymes are not associated with male pattern baldness. Finally, no clear inheritance pattern of male pattern baldness was observed. The relatively strong concordance for baldness between fathers and sons in this study was not consistent with a simple Mendelian autosomal dominant inheritance. A polygenic etiology should be considered.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1976

Olfacto-genital dysplasia in the female.

The clinical syndrome of OGD in the female is displayed as hypogonadism and most commonly type I hyposmia ("anosmia"). The main pathologic findings are absence of the olfactory bulbs and tracts, hypoplasia of the hypothalamus, a normal pituitary gland, and normal appearing, although unstimulated, ovaries. The syndrome of OGD may be considered as an attenuated form of holoprosencephaly. Various facial abnormalities have been observed in patients with OGD and their families. Thorough neurologic examination may reveal other abnormalities. In the majority of cases the etiology of OGD is not known; however, among about one-fourth of the females, other members of the family exhibit either OGD or anosmia, implying a genetic basis. In this familial form of OGD some pedigrees suggest an X-chromosomal pattern and others, an autosomal inheritance pattern. Although hypogonadotropic hypogonadism is usually considered the only endocrinologic abnormality, stimulatory test of pituitary and hypothalamic function may reveal poor responses of growth hormone. ACTH, prolactin, and possibly MSH. The administration of LRH has shown varying pituitary gonadotropin responses, implying, in some instances, an associated pituitary malfunction. However, these observations may be the result of variations in technic and, therefore, further data are necessary to clarify this issue. Cyclic estrogen and progestin administration stimulates secondary sexual sex characteristics. Exogenous gonadotropins are capable of stimulating ovarian steroidogenesis and, in most patients, inducing ovulation. Thre pregnancies have been reported.

Adolescent↗
PubMed1976

The inheritance of fingerprint patterns.

Analysis of the fingerprints of 571 members of the Habbanite isolate suggest inherited patterns and pattern sequences. A genetic theory has been developed; it assumes that the basic fingerprint pattern sequence is all ulnar loops and that a variety of genes cause deviations from this pattern sequence. Genes that have been proposed include: (1) a semidominant gene for whorls on the thumbs (one homozygote has whorls on both thumbs, the other has ulnar loops on both thumbs and the heterozygote usually has two ulnar loops or one ulnar loop and one whorl); (2) a semidominant gene for whorls on the ring fingers which acts like the gene for whorls on the thumbs; (3) a dominant gene for arches on the thumbs and often on other fingers; (4) one or more dominant genes for arches on the fingers; (5) a dominant gene for whorls on all fingers except for an ulnar loop on the middle finger; (6) a dominant gene for radial loops on the index fingers, frequently associated with an arch on the middle fingers; and (7) a recessive gene for radial loops on the ring and little fingers. These genes may act independently or may show epistasis.

Dermatoglyphics↗