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Biomedical subjects

L Iselius

Publications and source records attributed to L Iselius.

At least 37 records · Page 2Linked to original sources
PubMed1996

Migraine without aura and migraine with aura are inherited disorders.

The familial occurrence and mode of inheritance were analysed in families with migraine without aura (MO) and migraine with aura (MA). The probands were found among 4000 persons from the general population. All persons with MA were included as probands, and an equivalent number of probands with MO was selected as a random sample among those with MO. Spouses and first-degree relatives were blindly interviewed. All interviews were performed by one neurological research fellow. The distinct familial patterns indicate that MO and MA have a different aetiology. Compared with the general population, the first-degree relatives of probands with MO had a 1.9-fold increased risk of MO while spouses had a 1.5-fold increased risk of MO, indicating that both genetic and environmental factors are important in MO. The first-degree relatives of probands with MA had a four-fold increased risk of MA while spouses had no increased risk of MA, indicating that MA is determined largely by genetic factors. The complex segregation analysis indicated that both MO and MA have multifactorial inheritance without generational difference.

Adolescent↗
PubMed1995

Inheritance of migraine investigated by complex segregation analysis.

Migraine is the most common neurological disorder, affecting about 20% of adults. The mode of inheritance was analyzed in the two main types of migraine, migraine without aura (MO) and migraine with aura (MA), by complex segregation analysis using the computer program POINTER. We included 126 probands with MO and 127 probands with MA from the general population. First-degree relatives and spouses were blindly interviewed by a neurological research fellow. The complex segregation analysis indicated that both MO and MA have multifactorial inheritance without generational difference.

Adolescent↗
PubMed1995

Cluster headache is an autosomal dominantly inherited disorder in some families: a complex segregation analysis.

We investigated the mode of inheritance of cluster headache in 370 families. The probands were from a neurological clinic in Jutland and two departments of neurology in Copenhagen County, Denmark. The criteria of the International Headache Society were used. The patterns of segregation of cluster headache were assessed by complex segregation analysis performed with the computer program POINTER. Of the 370 probands with cluster headache, 25 had 36 relatives with cluster headache. The segregation analysis suggests that cluster headache has an autosomal dominant gene (p < 0.10) with a penetrance of 0.30-0.34 in males and 0.17-0.21 in females. The gene is present in 3 to 4% of males and 7 to 10% of females with cluster headache. An autosomal dominant gene has a role in cluster headache in some families.

Adolescent↗
PubMed1994

Severity of mutation in the phenylalanine hydroxylase gene influences phenylalanine metabolism in phenylketonuria and hyperphenylalaninaemia heterozygotes.

We examined whether the degree of residual activity from the mutant phenylalanine hydroxylase (PAH) allele affected phenylalanine metabolism in heterozygotes for phenylketonuria (PKU) or non-PKU hyperphenylalaninaemia (HPA). Discriminant analysis was carried out to find the function of fasting plasma concentrations of phenylalanine (PHE) and tyrosine (TYR) that best separated carriers from non-carriers. This function (0.103TYR -0.214-PHECORR -4.499) was subsequently used as the dependent variable, with the in vitro activity of the expressed mutant PAH as the independent variable, in a regression analysis performed on heterozygotes for mutations that had been studied in a eukaryotic cell expression system. This analysis showed a significant correlation (r = 0.40, n = 140, p < 0.001), although there was a wide spread of values within each of the two major groups of carriers and a considerable overlap between the groups. We conclude that the severity of the mutation, as determined by in vitro expression analysis, in the mutant PAH gene is reflected in the biochemical phenotype of heterozygotes. This result emphasizes the relevance of the cell expression system used for establishing the relative severities of most mutations at the PAH locus. Differences in the activities from the carried mutant PAH allele on phenylalanine metabolism in heterozygotes are, however, small compared to the activity from the normal PAH allele and are easily obscured by other factors leading to inter- or intra-individual variation in phenylalanine metabolism. Fasting plasma concentrations of phenylalanine and tyrosine thus can not be used to predict the severity of the carried PAH mutation in individual PKU or HPA heterozygotes.

Adult↗
PubMed1994

Genetic rearrangements in sporadic and familial gastric carcinomas detected with microsatellite markers.

Ten gastric carcinomas were studied for loss of heterozygosity by analysis of 21 microsatellite markers from 14 different chromosomes. Four patients had a family history of gastro-intestinal cancer, and six tumours were considered sporadic. We also studied a new mechanism in tumourigenesis recently reported in hereditary non polyposis colon cancer, a defect in mismatch repair that is seen as gain of new bands by the use of dinucleotide repeat markers. Loss of heterozygosity was detected with two markers in one primary tumour and with the majority of markers in one metastasis from a sporadic gastric tumour. Gain of microsatellite bands was seen in one tumour from a gene carrier in a family with hereditary non-polyposis colon cancer and in one sporadic tumour. Two tumours from patients with a family history of gastric cancer showed no rearrangements. Our results suggest that different types of genes are involved in initiation and progression of gastric cancer in sporadic and familial gastric cancer.

Adult↗
PubMed1994

Predisposition for breast cancer in carriers of constitutional translocation 11q;22q.

A translocation between the long arms of chromosomes 11 and 22, t(11;22)(q23;q11), is the most frequent constitutional reciprocal translocation in man. This chromosome abnormality has not previously been reported to be associated with an increased risk for neoplasia. The observation of one patient with a constitutional translocation t(11q;22q) and breast cancer prompted us to study the relationship between these two conditions. The incidence of breast cancer was determined in carriers of t(11q;22q). The karyotypes were determined by QFQ-banding, and the breakpoints were then further characterized by fluorescent in situ hybridization. Eight families with a total of 22 balanced carriers were found. In five of these families there was one case of breast cancer each. In another family a case of an unknown malignancy was reported in one member. No other malignancies were found among these patients. The number of breast cancer cases was significantly higher than expected among the translocation carriers (P < .001). The chromosomal breakpoints showed the same localization with the markers used, in the seven families studied. The association of constitutional translocation t(11q;22q) and breast cancer identifies a subset of patients with a highly increased risk for breast cancer who would benefit from counseling and screening. It also suggests the involvement of genes on 11q and/or 22q, in the tumorigenesis of breast cancer.

Breast Neoplasms↗
PubMed1993

Investigation of inheritance of chronic inflammatory bowel diseases by complex segregation analysis.

OBJECTIVE: To investigate the mode of inheritance of ulcerative colitis and Crohn's disease by complex segregation analysis. DESIGN: Cross sectional population based survey of familial occurrence of chronic inflammatory bowel disease. SETTING: Population of the Copenhagen county in 1987. SUBJECTS: 662 patients in whom inflammatory bowel disease had been diagnosed before 1979, of whom 637 (96%) provided adequate information. Of 504 patients with ulcerative colitis, 54 had 77 relatives with ulcerative colitis and of 133 patients with Crohn's disease, five had seven relatives with Crohn's disease. MAIN OUTCOME MEASURES: Patterns of segregation of either disease as assessed by complex segregation analysis performed with the computer program POINTER. RESULTS: The analysis suggested that a major dominant gene with a penetrance of 0.20-0.26 is present in 9-13% of adult patients with ulcerative colitis. The analysis did not allow for other components in the familial aggregation. For Crohn's disease the best fitting model included a major recessive gene with complete penetrance, for which 7% of the patients are homozygous. However, this model was not significantly different from a multifactorial model. CONCLUSIONS: The segregation pattern indicates that a major dominant gene has a role in ulcerative colitis, and suggests that a major recessive gene has a role in Crohn's disease.

Adolescent↗
PubMed1993

Polymorphic 2-hydroxylation of desipramine. A population and family study.

We have studied desipramine hydroxylation capacity, determined as the metabolic ratio of desipramine to 2-hydroxydesipramine in the urine after a single oral dose of 10 mg of desipramine, in 340 Swedish Caucasians, including the members of 45 two-generation families. Desipramine metabolic ratios were bimodally distributed among 237 unrelated subjects and 8% were poor metabolizers. There was a strong correlation between the metabolic ratios for desipramine and debrisoquine in 337 subjects phenotyped with both drugs and there was no dissociation between their capacities to hydroxylate desipramine and debrisoquine. Complex segregation analysis in the 45 families gave evidence for a major locus with incomplete recessivity (d = 0.14) controlling the 2-hydroxylation of desipramine. Similar results were obtained in segregation analysis for debrisoquine. There was evidence for linkage between the CYP2D6 gene and the gene regulating the hydroxylation of desipramine and debrisoquine. This study has provided unequivocal evidence that the capacity to 2-hydroxylate desipramine is polymorphic and under similar genetic control to the hydroxylation of debrisoquine.

Adolescent↗
PubMed1993

DNA polymorphisms in the human tyrosine hydroxylase/insulin/insulin-like growth factor II chromosomal region in relation to glucose and insulin responses.

The feasibility of disease association studies using polymorphic DNA markers in the tyrosine hydroxylase/insulin/insulin-like growth factor II chromosomal region was indicated by a high degree of linkage disequilibrium found in haplotypes. Haplotypes were resolved in the parents from Scandinavian nuclear families by studying the segregation of eight DNA polymorphisms. Comparison of observed vs expected frequencies of haplotypes, as well as pairwise measures of linkage disequilibrium, indicated a high degree of linkage disequilibrium. Five restriction fragment length polymorphisms linked to the tyrosine hydroxylase/insulin/insulin growth factor II region of chromosome 11 were investigated in relation to Type 2 (non-insulin-dependent) diabetes mellitus, and to glucose and insulin responses to glucose infusion in healthy subjects. No significant differences in genotype frequencies between Type 2 diabetic (n = 53) and healthy subjects (n = 106) were found. A significant association (p < 0.001) was initially found between genotypes defined by a PstI polymorphism located 5' of the tyrosine hydroxylase gene and the early glucose response to a standardized glucose infusion test in healthy subjects. However, a follow-up study of 112 healthy individuals failed to confirm this finding.

Alleles↗
PubMed1993

Early child health in Lahore, Pakistan: II. Inbreeding.

The prevalence of consanguineous marriages was studied in 940 families belonging to four different socio-economic groups in and around Lahore, Pakistan. The births occurring in these families from September 1984 to March 1987 were also investigated for birth defects. The overall prevalence of consanguineous marriages was 46%. The first cousin marriages were most common (67%), followed by the marriages between second cousins, 19%. The prevalence of consanguineous marriages was clearly associated with the socio-economic status of the study groups; 50% of the marriages was related in the periurban slum, 49% in the village, 44% in the urban slum and 31% in the upper middle class. The birth defects were also more prevalent in the poorer areas, being highest in the periurban slum (17.7%) followed by the urban slum (15.6%) and then the village (14.8%) and lowest in the upper middle class (12.3%). Although, the frequency of both consanguinity and birth defects were related with the socio-economic levels of the study groups, there was no association between inbreeding and birth defects. Perhaps, deleterious recessive genes for birth defects have been "bred out", because of continuous inbreeding over generations in this population. There was a significant predilection of major birth defects in boys without clear sex linkage. The conclusion is that the rate of consanguineous marriages was high, especially in the poorer areas, but the relationship between consanguineous marriages and birth defects was little or none. However, other child health indicators may be affected by consanguineous marriages.

Adult↗
PubMed1992

Hereditary breast cancer in Sweden: a predominance of maternally inherited cases.

The family history of breast cancer was studied in 1975 breast cancer patients of all ages. All the patients were found in an ongoing care program for breast cancer patients in the Stockholm area. One hundred and thirty-three families (6.7%) with hereditary breast cancer, 87 (4.4%) families with hereditary breast- and other cancers, and 14 (0.7%) families with the SBLA syndrome were found. There was no association between familiarity and bilateral disease, but familial cases tended to be younger at the time of diagnosis. Determination of the parental origin of the disease gene among the index cases revealed twice as many cases where the disease was maternally transmitted. This might be due to a better prognosis when the predisposing gene is maternally transmitted, and could be explained by parental imprinting or environmental factors influencing the expression of the gene.

Age Factors↗
PubMed1992

Pronounced differences between native Chinese and Swedish populations in the polymorphic hydroxylations of debrisoquin and S-mephenytoin.

The frequency of poor metabolizers of debrisoquin was low and similar in four different native Chinese nationalities. In a total sample of 695 Chinese subjects, only seven (1.01%) had a urinary ratio between debrisoquin and 4-hydroxydebrisoquin greater than 12.6, which is the antimode between poor metabolizers and extensive metabolizers in white populations. This is significantly lower than the 6.82% found in 1011 white Swedish healthy subjects (p less than 0.0001). Admixture analysis indicated the occurrence of two distributions within extensive metabolizers among both Chinese and white subjects. The mean of the distribution of metabolic ratios among Chinese extensive metabolizers was shifted toward higher values compared with Swedish extensive metabolizers (p less than 0.01). The frequency of poor metabolizers of S-mephenytoin was higher in 137 Chinese (14.6%) than in 488 Swedish (3.3%) subjects (p less than 0.0001). Our findings imply that drugs metabolized by these two polymorphic hydroxylases should be prescribed in different dosages to Chinese and white subjects.

China↗
PubMed1992

Transmission of breast cancer--a controversy resolved.

The Danish breast cancer data collected by Jacobsen (1946) have been reanalysed using morbid risks which incorporate mortality due to breast cancer. A dominant gene is favoured for familial breast cancer, supporting the conclusions of Williams & Anderson (1984) and later authors. Neglect of specific mortality does not greatly alter estimates of gene frequency and displacement, but the evidence for a major gene is inflated. No evidence for heterogeneity was found. Earlier claims of non-Mendelian transmission are in error since we have discovered that transmission probabilities are not correctly implemented in the computer program POINTER. Cases with bilateral breast cancer and males with breast cancer all belonged to families favouring a major gene. Of the cancer sites frequently reported to be associated with familial breast cancer, only ovarian cancer is significant in this material.

Breast Neoplasms↗
PubMed1991

DNA haplotype analysis suggests linkage disequilibrium in the human insulin receptor gene.

Haplotypes of the insulin receptor gene were resolved in parents from Scandinavian nuclear families by studying the segregation of seven restriction fragment length polymorphisms (RFLPs). Of 97 unrelated parents, 41 had non-insulin-dependent diabetes mellitus (NIDDM). Considerable linkage disequilibrium in the region of the insulin receptor gene was found. Pairwise non-random associations were found between proximate RFLP sites, indicating the absence of recombinational hot spots between these sites. Thus, association studies between DNA polymorphisms at this locus and disease susceptibility genes could well be feasible in this population. Differences in the distribution of insulin receptor haplotypes were examined between NIDDM patients and healthy subjects. However, the differences observed were not statistically significant.

Adult↗