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Biomedical subjects

L Iselius

Publications and source records attributed to L Iselius.

105 records · Page 6Linked to original sources
PubMed1981

Segregation and linkage analysis of 40 multiplex multiple sclerosis families.

40 multiplex multiple sclerosis (MS) families were analyzed for evidence of an MS susceptibility gene linked to the HLA region of the sixth chromosome. We assumed that population associations between specific HLA alleles and MS are due to linkage disequilibrium, so preference was given to hypotheses compatible with tight linkage, and explanations were sought for conflicting evidence. The analyses proceeded in two steps: (1) segregation analysis using the computer program POINTER, and (2) linkage analysis using LINKAS, first assuming linkage equilibrium and then allowing for linkage disequilibrium and etiological heterogeneity. The results of the segregation analyses were indeterminate. The results of the linkage analyses suggest that analyses that do not allow for disequilibrium lose substantial evidence on linkage. Of the models that were investigated under linkage disequilibrium, the best fit is with a model of complete linkage (theta= 0.0) in 75% of the pedigrees and no linkage in the remaining pedigrees. We were unable, however, to statistically reject another model involving loose linkage and no heterogeneity.

Chromosomes, Human, 6-12 and X↗
PubMed1981

Incidence of Down's syndrome in Sweden during the years 1968-1977.

The incidence of Down's syndrome has been studied among children born in Sweden during the years 1968-1977. The risk for mothers of different ages of bearing such a child did not change during these years. This does not exclude that a change in incidence might have occurred in smaller areas of the country but escaped detection for statistical reasons. A higher than expected number of children with Down's syndrome were born in a few communities, which most likely is a chance event. No correlation could be detected between the incidence of Down's syndrome and a number of socioeconomic variables. The correlation with maternal age was studied in detail. There was a significant excess of males among both the newborn children with Down's syndrome and fetuses with trisomy 21 aborted after prenatal diagnosis. A similar tendency was found among the cases with a chromosome mosaicism but not among those with a translocation. Two hypotheses are put forward to explain the excess of males with trisomy 21.

Adolescent↗
PubMed1981

Genetic aspects of psoriasis: mode of inheritance and action of PUVA on DNA.

The results of some family and experimental studies related to psoriasis are summarized. Complex segregation analysis of Lomholt's classical family material of psoriasis from the Faroe Islands gave clear evidence of a major locus (additive gene with a frequency of 0.07) plus a strong polygenic component (genetic heritability 0.87). An analysis of another family material showed complete linkage between the major locus for psoriasis and the HLA region. Treatment of cells with 8-methoxypsoralene plus a small dose of UVA induces monoadducts, some of which appear to remain in the DNA for at least 7 days of post-treatment incubation. These monoadducts can be activated to form DNA cross-links by a second, larger UVA dose. 8-Methoxypsoralene plus UVA-induced DNA cross-links can be modified by a repair process which involves the formation of DNA breaks. This process in not observed in XPA cells.

DNA↗
PubMed1980

Ring chromosome 14 in a mentally retarded girl.

A case of ring chromosome 14 in a 12-year-old girl, showing mental retardation, epilepsy and minor somatic abnormalities, is described and compared with five previously reported cases with the same chromosome aberration.

Abnormalities, Multiple↗
PubMed1979

A major locus for hyper-beta-lipoproteinemia with xanthomatosis.

Complex segregation analysis of hyper-beta-lipoproteinemia with xanthomatosis has provided strong evidence for a major locus, in addition to significant polygenic effect and sibling environment. Estimates of gene frequency agree with values generally given in the literature.

Chromosome Mapping↗
PubMed1979

Analysis of family resemblance for lipids and lipoproteins.

A path analysis of published reports on family resemblance reveals an important role for genetic factors in all lipids and lipoproteins, with no evidence of a discrepancy between twins and other relatives (which might be due to dominance or epistasis) nor between studies which used environmental indices and those which did not. Family environment within population is less important and is significantly greater for twins than for other relatives.

Cholesterol↗
PubMed1979

Unusual XX/XY chimerism.

Apparently identical twin boys are both XX/XY and have two populations, A1 and B, of cells in their peripheral blood. Chimerism in somatic tissue outside the blood cells can be demonstrated in only one of the twins. From analysis of chromosomes and many gene markers the mechanism of origin of the unusual twins remains unclear.

ABO Blood-Group System↗
PubMed1976

Somatomedin A in human serum, determined by radioreceptor assay.

Somatomedin A was determined by radioreceptor assay in serum from patients with various disorders. The mean values of somatomedin A in serum from 20 adult subjects, 21 patients with acromegaly, and 17 patients with hypopituitary dwarfism were 1.08 +/- 0.08, 3.02 +/- 0.33 and 0.44 +/- 0.03 U/ml, respectively. In children below 2 years of age, low levels were found (mean 0.40 +/- 0.04 U/ml). Normal levels were found in patients with Turner's syndrome and primary hypothyroidism, increased levels in uraemic patients, and decreased levels in Laron dwarfs.

Acromegaly↗
PubMedDate not supplied

Cluster headache is an inherited disorder in some families.

We investigated the familial occurrence of cluster headache in 370 probands with cluster headache, diagnosed according to the operational diagnostic criteria of the international Headache Society. Seven probands belonged to three families. A positive family history of cluster headache was found in 7% (25 of 366) of the families. Compared with the general population, the first- and second-degree relatives of the 370 probands with cluster headache had a 14- and 2-fold increased risk of having cluster headache, after standardization for sex and age. This increased familial risk strongly suggests that cluster headache has a genetic cause. The patterns of segregation were assessed by complex segregation analysis performed with the computer program, POINTER. The segregation analysis suggests that cluster headache has an autosomal dominant gene with a penetrance of 0.30 to 0.34 in males and 0.17 to 0.21 in females. The gene is present in 3% to 4% of males and 7% to 10% of females with cluster headache.

Adolescent↗
PubMedDate not supplied

Formal genetics of isoniazid metabolism in man.

Complex segregation analysis of the isoniazid inactivator phenotype has shown the existence of a recessive gene and a multifactorial background. The phenotype is also influenced by age, sex and weight. The relevance of these findings to the grouping of individuals into slow and rapid inactivators is stressed.

Acetylation↗