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[Epidemiological study of healthy carriers of Australia antigen. Analysis of contagiousness, and mechanism of spread of the infection (author's transl)].

Epidemiological studies in healthy carriers of HB Ag show variable results that might depend on the geographical area, ethnic group, and socio-economic level analyzed. For that reason an study was undertaken in the Spanish population with the purpose of analysing contagiousness of healthy carriers and mechanism of spread of the infection. The incidence of HB Ag and HB Ab was determined by radioimmunoassay in 211 relatives of 76 healthy carriers; all members of the family could be studied in 51 cases. The results were compared to those of a sizeable sample of the normal population. The overall incidence of HB Ag (13.1 %), and of HB Ab (18.9 %) in the probands was significantly higher than in the normal population (0.8 %, and 9 %, respectively). The distribution of new cases of HB Ag positivity in the 51 families in which the members could be studied demonstrated a significantly higher frequency in children of a carrier mother (28.9 %) than in those of a carrier father (10.8 %). In conclusion, the contagiousness of healthy carriers for their families can not be disregarded. It is likely that the mechanism of spread of the infection depends on a multifactorial inheritance of the genetic alteration of the selective immunologic response to the HB Ag, compounded by environmental factors.

Blood Donors↗

[Congenital defects of the diaphragm in siblings. Two case reports (author's transl)].

In two different families each time two siblings head a congenital defect of the diaphragm, in 3 cases of the posterolateral type, in 1 case an almost complete aplasia of the diaphragm. Usually, the occurrence of defects of the diaphragm is sporadic. However, familial occurrence has been reported in 15 cases. Multifactorial inheritance is most likely the explanation for this. With this hypothesis a risk of 2% can be calculated for the recurrence of this malformation in a family with already one affected child.

Diaphragm↗

[Hereditary diseases and congenital malformations at the Unit of Medical Genetics of the University of Zulia. Years: 1983-1992].

The Medical Genetics Unit at Universidad del Zulia (UGM-LUZ) gives counsel to patients with partial and total genetic diseases. Counseling is available for patients of both sexes and all ages, from public and private health centers and several medical specialities. In the present study an analysis of 4617 clinical records from families referred for genetic counseling to the UGM-LUZ is given. The study spans from January 1983 to December 1992. Fifty four (1.2%) of these histories correspond to pre-nuptial counseling, 773 (16.7%) pre-conceptional, 316 (6.8%) pre-natal and 3474 (75.3%) for diagnosis. A computerized system was developed, based on relational data base manager, that permits access with interactive Dbase type applications. A total of 5433 diagnoses were made. The most frequent causes of genetic diseases were chromosomal abnormalities (12.32%), mainly Down and Turner syndromes. Mendelian diseases occupied 14.45% of all cases, with Marfan and Noonan syndrome, Osteogenesis imperfecta. Duchenne-Becker muscular dystrophy and Incontinentia Pigmenti as the most frequent syndromes. Diseases that involve multifactorial inheritance, such as neural tube defects, accounted for 7.36% of all diagnosis. Effects of teratogenic agents such as german measles, radiations and others were detected in 3.96% of all cases. In 8.5% of the patients a hereditary factor was suspected. No definitive diagnosis was reached in 32.45% of all cases and 20.96% of the patients were normal. The need for data from other medical genetic centers is stressed. In this way the regional and national genetic diseases on morbidity can be known.

Adolescent↗

Positron emission tomography studies of abnormal glucose metabolism in schizophrenic illness.

Advances in psychopharmacology and neuroscience have brought into view a wide field of competing mechanisms for the etiology of schizophrenia including, but not limited to, deficits in one or more neurotransmitters (dopamine, serotonin, GABA, glutamate, and noradrenaline systems), neurodevelopmental defects in cortical connectivity, and viral infection. Genetic studies suggest heterogeneity in the illness, with multifactorial inheritance. Since cerebral metabolic activity reflects regional brain work for all neurotransmitter systems, imaging studies can provide information on the functional neuroanatomy of a deficit in the individual patient, allowing the grouping of patients for more intensive investigation in more homogeneous groups. Metabolic imaging studies allow psychopharmacological response to be regionally assessed and clinical responders to be identified, even for medications that affect more than one neurotransmitter system or have clinical effects that derive from changes in activity one synapse or more removed from the site of primary action.

Brain↗

[Infrarenal aortic aneurysms. 2. Occurrence, diagnosis and treatment].

Infrarenal aortic aneurysms exhibit multifactorial inheritance with massive familial occurrence. Several large screening programmes have shown a general prevalence of about 3% in nonselected populations of patients over 60 years. Danish data on this point are not available, but is seems reasonable to suspect that 30,000-40,000 Danes have the disease. Only 450 operations for infrarenal aortic aneurysms are performed each year in Denmark (population 5.1 mill.). The current information with respect to incidence, prevalence, expansion rate, therapeutical strategies and results of vascular surgical reconstruction is reviewed.

Aortic Aneurysm, Abdominal↗

[Effect of heredity and environment in immune diseases. Presentation of twin data].

BACKGROUND: The study of twins is an important and informative tool in the investigation of the influence of genetic and environmental factors on the pathogenesis of familial traits. MATERIAL: Seven diseases were analysed by carrying out an intensive study of the literature to search for concordance of monozygotic and dizygotic twins. Apart from single case studies, large unselected series have been reported, some of which show considerable differences in concordance rates. Data from twins were collected for myasthenia gravis, systemic lupus erythematosus, rheumatoid arthritis and type 1 diabetes mellitus, Crohn's disease and, for comparative purposes, also type 2 diabetes mellitus. RESULTS: On the basis of the above-mentioned calculated concordance rates, differences in the influence of genetic factors were established, which may be of importance for the genetic counselling of affected families. These findings based on twins also confirm the multifactorial inheritance model.

Adolescent↗

[Evidence of a major gene in cleft lip/palate susceptibility by means of segregational analysis in the Chilean population].

The most generally accepted model for cleft lip/palate not associated to specific syndromes has been the one that postulates multifactorial inheritance with a threshold. Recent studies using complex analytical techniques have suggested the existence of a major gene with decreased penetrance in its etiology. Some authors have postulated that only a fraction of all cases of non-syndromic CL (P) would be explained by a single major gene. Other cases may be due to different genes, to environmental agents or to the interaction between them. The present study tests the monogenic inheritance model for CL (P) using segregation analysis in a sample of 211 extended pedigrees collected through CL (P) affected probands. The hypotheses of an autosomic recessive gene was analyzed in 151 sibships (size 2 or more) using "Apert's" method, "maximum likelihood method", "singles method" and "sib's, method" (single incomplete ascertainment). Results obtained do not support the hypotheses of autosomal recessive inheritance. Instead, the hypothesis of an autosomal dominant mode of inheritance with low penetrance is not rejected when analyzing the proportion of normal and affected progeny in certain types of matings in a subsample of 30 extended pedigrees with two or more affected individuals.

Chile↗

Familial vesico-ureteral reflux.

Four families of which 2 or more members were affected with primary vesico-ureteral reflux are reported. A multifactorial inheritance pattern subject to environmental factors is likely. Early examination and detection of the disorder in relatives at risk provide an opportunity to avoid the serious sequelae of vesico-ureteral reflux.

Child↗

Genetic studies of atopy and atopic dermatitis.

Atopy and the atopic disorders are likely to result from multifactorial inheritance, with interaction between genetic and environmental factors. It has been proposed that at least two major mechanisms, non-antigen specific (total IgE levels) and antigen specific (specific IgE antibodies and skin tests), regulate the immune response to allergens in humans: firstly, a gene/genes independent of the human leucocyte antigen system which is involved in the regulation of total IgE levels, and secondly, a specific immune response gene/genes associated with major histocompatibility complex class II genes which are involved in antigen-specific mechanisms. Candidate genes have been proposed for both mechanisms and linkage has been found between atopy and at least three different gene loci. This paper reviews the evidence supporting a genetic basis for atopy and atopic dermatitis and outlines recent advances in the molecular genetic mapping of genes associated with these disorders.

Dermatitis, Atopic↗

[Immunopathologic disorders in atopic dermatitis].

The atopic dermatitis is a multifactorial inheritable disease, in which pathogenesis in addition to environmental factors (climate, allergens, clothing) genetically determined multiplex metabolic differences (arachidonic acids, essential fatty acids) and immunologic alterations play an important role. Within immunologic findings the disturbances of balance in Th1 and Th2 subclasses, the increased degranulation activity of mast cells and the increased antigen presentation activity of Langerhans cells can be stressed. The clinical immunological alterations shown in the diseases, the increased production of IgE and so the type I. allergic reactions (urticaria, gastrointestinal manifestation of food allergy, allergic rhinitis, asthma bronchiale), the difference of cellular immunity of the skin can be explained by the above mentioned main immunological changes. In understanding of immunological origin of atopic dermatitis the IgE receptors expressed on the surface of Langerhans cells (connecting the immediate and delayed type of immune response) mean significant help.

Allergens↗

Concordant anencephaly in monoamniotic twins and an analysis of maternal serum markers.

Anomalies occur with greater frequency in twin gestations than in singleton pregnancies. Anencephaly is not an uncommon defect, but because of its multifactorial inheritance pattern, twins are usually discordant for this anomaly. We present a case of monoamniotic twins concordant for anencephaly. Monoamniotic anencephalic twins were diagnosed at 15 weeks' gestation. Normal interval growth occurred until intrauterine demise of both fetuses at 28 weeks. Maternal serum obtained at 16.5 weeks demonstrated low unconjugated oestriol (uE3) levels and elevated values of alpha-fetoprotein, although this result was lower than expected. Human chorionic gonadotropin (hCG) levels were significantly elevated. Monoamniotic twins concordant for anencephaly occur with extreme rarity. To our knowledge, maternal serum uE3 and hCG levels in fetuses concordant for neural tube defects have not been previously reported.

Adolescent↗

[A study of genetic patterns of idiopathic epilepsy].

OBJECTIVE: To explore genetic patterns of idiopathic epilepsy (IEP). METHODS: Using familial analysis, tests for multifactorial inheritance and segregation analysis, we studied 210 pedigrees with IEP found in a population survey in Shangdong province. RESULTS: The genetic pattern of IEP is not polygenic but is mainly influenced by autosomal recessive disorders. The results of segregation analysis indicate that the genetic pattern of U*U multiplex families and U*A group is autosomal recessive. Only a few cases in U*U group may accept the assumption of autosomal recessive inheritance while the other are sporadic cases. The frequency of sporadic cases is approximately 78.5%. Genetic heterogeneity may influence U*U(f) group and U*U group. CONCLUSION: Further and careful empirical scrutiny of U*U(f) group and the sporadic cases in U*U group offers the best hope for getting a clear understanding of genetic patterns and mechanisms in IEP.

Epilepsy↗

Familial atrial septal defect with atrioventricular conduction defects.

Atrial septal defect of the ostium secundum type is almost always sporadic, with multifactorial inheritance. We report a case of a family in which atrial septal defects of the ostium secundum type with atrioventricular conduction defects were observed in four generations: five proven cases and two probable cases. Ten families have been reported as showing atrial septal defect of the ostium secundum type and atrioventricular conduction defects with dominant inheritance. Moreover, in our family the transmission model can also confirm autosomal dominant inheritance. We believe that cardiologists should take a familial approach to atrial septal defect of the ostium secundum type for both research and genetic counseling purposes. In a patient with ASD II, the AV conduction defects should prompt a detailed family history and clinical evaluation of first-degree relatives.

Adult↗

[Familial occurrence of chronic tension headache].

Chronic tension-type headache occurs in 3% of the Danish population. the aetiology remains an enigma, even though it is one of the most frequent illnesses with chronic pain. A family study indicates the importance of genetic factors. Compared with the general population, first degree relatives (parents, siblings and children) of probands with chronic tension-type headache have a three-fold significantly increased risk of chronic tension-type headache, while spouses had no increased risk. Complex segregation analysis indicates multifactorial inheritance. Thus, a combination of genetic and environmental factors causes chronic tension-type headache.

Adult↗

[Possibility of the current segregation analysis to discriminate between monogenic and multifactorial types of inheritance of traits. The effect of the structure of family data on model robustness and power of the analysis].

The influence of sampling designs for robustness of the autosomal major locus model and the multifactorial model as well as possibility of segregation analysis to discriminate these models was studied. Nuclear families and 3-generation pedigrees were considered. It was found that robustness of models increased, when the size of sibships in nuclear families grows and when configuration of pedigrees is complicated. The resolution power of the analysis is always increased with size elevation of sibships, the highest effect of the analysis being observed for sibships of the size 3 or 4. Consideration of new generations is only advisable, if attracting sibs of these generations, the resolution power being increased, provided that the parameters of models are of high value.

Genetics, Population↗

Familial patterns and possible modes of inheritance of primary affective disorders.

A logistic model was used to analyze the pattern of affected relatives of probands with primary affective disorders (PAD). The sample consisted of 242 patients, diagnosed as either unipolar (UP, 107) or bipolar (BP, 135) and 430 control nonpsychiatric inpatients and all first degree relatives of both groups. Age correction was applied to both groups. The analysis showed a significant baseline increase in frequency of PAD among relatives of PAD probands with siblings more likely to be affected than parents. The difference in frequency of PAD according to sex of relative almost reached significance. Specific diagnosis (UP or BP) of proband did not significantly affect the probability of relatives becoming ill. Genetic models incorporating sex-specific thresholds were able to explain the data satisfactorily as resulting from either Single-Major-Locus inheritance or Multifactorial-Polygenic inheritance.

Bipolar Disorder↗

Genetic studies of febrile convulsions: analysis of twin and family data.

Children with febrile convulsions (FC) including 46 twin pairs, 1913 families including 393 sibling pairs, and 42 three-generation FC kindreds have been studied. Twin studies: (1) The pairwise concordance rate for FC was 69% (18/26 pairs) in monozygotic (MZ) and 20% (4/20 pairs) in dizygotic (DZ) twins (P less than 0.01). (2) The intra-pair similarity of clinical symptoms in 18 concordant MZ twin pairs showed a positive significant correlation, particularly in 4 items--duration of seizure, exogenous factors, intelligence level, and background EEG abnormality. These correlations were greater than those in sibling pairs. (3) No evident cause for discordance was detected in 8 discordant MZ twin pairs, and many dissimilar symptoms were observed in 4 concordant DZ twin pairs. Sibship studies: A large positive correlation of some clinical symptoms was observed in sibling pairs concordant for FC: age at onset of FC, degree of fever, duration of seizure, exogenous factors, and background EEG abnormality (r = +0.2- +0.6). Family history analysis: Morbidity risk among near relatives (17% in parents, 23% in siblings) than in second- (6.1%) or third-degree relatives (4.6%). The difference was found between: sibling greater than parents, uncles greater than aunts, male cousins greater than female cousins. Segregation analysis showed maternal preponderance. In 42 three-generation kindreds the morbidity risk was higher in siblings (32%), uncles/aunts (14%), and cousins (6.4%) than in relatives of other probands. Characteristic findings in FC patients with family history: Characteristic findings in FC patients with an FC parent or sibling, compared with those with no family history, were early onset of FC, lower degree of fever, longer duration of seizure, many recurrences, FC recurrence after age 3, and background EEG abnormality. Similar findings were more markedly observed in 42 3-generation kindreds. Mode of inheritance: A multifactorial mode of inheritance for FC receives some support from this study, and the heritability was estimated as 75%.

Child, Preschool↗