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P Propping

Publications and source records attributed to P Propping.

At least 37 records · Page 2Linked to original sources
PubMed2002

[Genetics of bipolar affective disorders. Current status of research for identification of susceptibility genes].

Bipolar affective disorder is a highly heritable condition, as evidenced by twin, family, and adoption studies. However, the mode of inheritance is complex and linkage findings have been difficult to replicate. Despite these limitations, consistent linkage findings have emerged for several chromosomes, notably 3p12-p14, 4p16, 10q25-q26, and 12q23-q24. Three additional areas, 13q32-q33, 18p11-q11, and 22q12-q13, have shown linkage in regions that appear to overlap with linkage findings in schizophrenia. These chromosomal regions might harbour genes that contribute to the development of bipolar affective disorder. Recent candidate gene studies include some positive results for the serotonin transporter gene (5-HTT) on 17q11-q12 and the catechol-O-methyltransferase gene (COMT) on 22q11. New methods are being developed for linkage disequilibrium mapping and candidate gene approaches. One can be optimistic that over the next few years bipolar susceptibility genes will be identified.

Bipolar Disorder↗
PubMed2002

The hairless gene in androgenetic alopecia: results of a systematic mutation screening and a family-based association approach.

BACKGROUND: Genetic disposition and androgen dependence are important characteristics of the common patterned loss of scalp hair known as androgenetic alopecia (AGA). The genetic factors contributing to AGA are currently unknown. The human hairless gene (HR) has recently been cloned and mutations have been reported in families with autosomal recessive universal congenital alopecia and papular atrichia. The main feature of these disorders is persistent complete absence of hair at or shortly after birth. This suggests that HR is essential and specific for the development of hair. OBJECTIVES: To test the hypothesis that HR may be involved in AGA. METHODS: We systematically screened HR for genetic variability by means of single-strand conformation analysis (SSCA) in 46 unrelated men with AGA. To test for an involvement of HR in the development of AGA, seven common variants were genotyped in 61 families with 93 affected offspring. The results were analysed with the transmission/disequilibrium test (TDT). RESULTS: SSCA showed 15 single nucleotide substitutions: eight missense mutations, four silent mutations and three mutations in exon-flanking intronic sequences. TDT results showed a marginally significant association between AGA and variants 3379-29G/T (P = 0.024) and 2611-68C/T (P = 0.047). These results, however, did not remain significant after applying the conservative Bonferroni correction for multiple testing. CONCLUSIONS: Our results do not provide evidence for a strong involvement of HR in the development of AGA, although a minor role cannot be fully excluded.

Adult↗
PubMed2002

A similarity-based method for genome-wide prediction of disease-relevant human genes.

MOTIVATION: A method for prediction of disease relevant human genes from the phenotypic appearance of a query disease is presented. Diseases of known genetic origin are clustered according to their phenotypic similarity. Each cluster entry consists of a disease and its underlying disease gene. Potential disease genes from the human genome are scored by their functional similarity to known disease genes in these clusters, which are phenotypically similar to the query disease. RESULTS: For assessment of the approach, a leave-one-out cross-validation of 878 diseases from the OMIM database, using 10672 candidate genes from the human genome, is performed. Depending on the applied parameters, in roughly one-third of cases the true solution is contained within the top scoring 3% of predictions and in two-third of cases the true solution is contained within the top scoring 15% of predictions. The prediction results can either be used to identify target genes, when searching for a mutation in monogenic diseases or for selection of loci in genotyping experiments in genetically complex diseases.

Algorithms↗
PubMed2001

Different familial transmission patterns in bipolar I disorder with onset before and after age 25.

Gene identification in common disorders such as Alzheimer disease and breast cancer has greatly profited from the use of age of onset as criterion to delineate subgroups of disease characterized by different inheritance patterns. In bipolar affective disorder, where the majority of linkage studies have produced conflicting results, studies reporting clinical characteristics and familial occurrence of disease have suggested that age of onset might serve as an indicator for identifying more homogeneous subgroups of disease. Our study was the first to examine this hypothesis by the means of segregation analysis. We investigated a sample of 177 bipolar I probands recruited from consecutive admissions and their first- and second-degree relatives (2,407 subjects). Probands were subdivided into an early-onset (n = 107) and a late-onset group (n = 70) using an age of onset of 25 as a cut-off point. This age was chosen because the observed age of onset distribution was bimodal with a cut-off of 25 years. Morbid risks for affective disorder were found significantly higher (P = 0.01) in relatives of probands with an early onset than in probands with late onset of disease. The segregation analysis showed that the disease is transmitted differently in early- and late-onset groups. In the early-onset group, a non-Mendelian major gene with a polygenic component was favored while the data in the late-onset group were compatible with a multifactorial model. This result may have important implications for future molecular studies aiming at the identification of disease-associated genes.

Adult↗
PubMed2001

A genome screen for genes predisposing to bipolar affective disorder detects a new susceptibility locus on 8q.

Bipolar affective disorder (BPAD), also known as manic depressive illness, is a severe psychiatric disorder characterized by episodes of mania and depression. It has a lifetime prevalence of approximately 1% in all human populations. In order to identify chromosomal regions containing genes that play a role in determining susceptibility to this psychiatric condition, we have conducted a complete genome screen with 382 markers (average marker spacing of 9.3 cM) in a sample of 75 BPAD families which were recruited through an explicit ascertainment scheme. Pedigrees were of German, Israeli and Italian origin, respectively. Parametric and non-parametric linkage analysis was performed. The highest two-point LOD score was obtained on 8q24 (D8S514; LOD score = 3.62), in a region that has not attracted much attention in previous linkage studies of BPAD. The second best finding was seen on 10q25-q26 (D10S217; LOD score = 2.86) and has been reported in independent studies of BPAD. Other regions showing 'suggestive' evidence for linkage localized to 1p33-p36, 2q21-q33, 3p14, 3q26-q27, 6q21-q22, 8p21, 13q11 and 14q12-q13. In addition, we aimed at detecting possible susceptibility loci underlying genomic imprinting by analyzing the autosomal genotype data with the recently developed extension of the GENEHUNTER program, GENEHUNTER-IMPRINTING. Putative paternally imprinted loci were identified in chromosomal regions 2p24-p21 and 2q31-q32. Maternally imprinted susceptibility genes may be located on 14q32 and 16q21-q23.

Bipolar Disorder↗
PubMed2001

Lack of association between a functional polymorphism of the cytochrome P450 1A2 (CYP1A2) gene and tardive dyskinesia in schizophrenia.

Tardive dyskinesia (TD) is a common side effect of long-term medication with typical neuroleptics. TD presents itself by abnormal involuntary movements and may lead to a potentially disabling and chronic clinical course. A vast majority of patients suffering from schizophrenia are smokers. Smoking has been reported to induce the activity of the CYP1A2 enzyme, which is an established metabolic pathway within the disposition of antipsychotics. Recently, a C-->A genetic polymorphism in the first intron of the CYP1A2 gene was reported to influence CYP1A2 activity in smokers. Subsequently, a pharmacogenetic study in 85 U.S. patients with schizophrenia (44 smokers, 41 individuals with unknown smoking status) showed the C/C genotype to be associated with higher TD severity (measured by the Abnormal Involuntary Movement Scale, AIMS) than the A/C or A/A genotype. This finding prompted us to investigate whether this effect was also present in a larger German sample of 119 patients with schizophrenia (82 smokers, 37 individuals with unknown smoking status). However, we could not replicate the reported association. The median AIMS scores did not differ between individuals with the A/A, A/C, or C/C genotypes. In an additional analysis, we compared the genotypic and allelic distribution among individuals grouped according to the criteria established by Schooler and Kane [1982: Arch Gen Psychiatry 39:486-487] (persistent TD vs. absent TD). We did not observe a differential genotypic or allelic distribution between the two diagnostic groups. Thus, our results do not support the hypothesis that the C-->A polymorphism in the CYP1A2 gene is involved in the etiology of TD in the German population.

Adult↗
PubMed2001

No association between a promoter dopamine D(4) receptor gene variant and schizophrenia.

The dopamine D(4) receptor has been implicated in the pathogenesis of schizophrenia. An association between a putative functional promoter polymorphism (-521C/T) in the dopamine D(4) receptor gene (DRD4) and schizophrenia was recently reported. In the present study, patients with schizophrenia (n = 132) and control subjects (n = 388) were analyzed with respect to the DRD4 - 521C/T polymorphism. No significant case control differences emerged. The present results do not support a major role for DRD4 in the etiology of schizophrenia among Caucasians from Sweden.

Adult↗
PubMed2001

Caught in the trio trap? Potential selection bias inherent to association studies using parent-offspring trios.

During the last years, the validity of classic case control studies in psychiatric genetic research has been increasingly under question due to the risk of population stratification problems inherent to this type of association study. By consequence, the application of family-based association studies using parent-offspring trios has been strongly advocated. Recently, however, in a study comparing clinical characteristics between index patients from parent-offspring trios and singleton patients with bipolar affective disorder, the question was raised whether a systematic neglect of case control association studies could lead to a selection bias of susceptibility genes. In a similar approach, we compared demographic and clinical characteristics of 122 singleton bipolar patients with those of 54 bipolar patients derived from parent-offspring trios. The singleton patients did not only present with a higher age of onset, but also with a higher frequency of suicidal behavior and a higher familial loading for suicidality. These findings suggest that the genetic mechanism for disease might be different between trio-based and classic case control samples, where patients are examined whose parents are not available for genetic studies. Thus, giving up case control designs for the sake of family-based association studies could be at the risk of selecting against several genetically determined factors.

Adult↗
PubMed2001

[Hereditary colorectal carcinoma: predictive diagnosis and genetic counseling].

5 to 10 percent of colorectal cancers occur due to a genetic predisposition. Familial adenomatous polyposis (FAP) and hereditary non-polyposis colorectal cancer (HNPCC) belong to the autosomal-dominant inherited colorectal cancer syndromes. First degree relatives of affected persons are at high risk for colorectal cancer and therefore should undergo regular surveillance programs. The genetic background of FAP and HNPCC is known today, but not in every affected family the germline mutation causing the inherited disorder can be found. In some cases identification of a germline mutation is helpful to confirm a suspected diagnosis in a patient. In almost all cases it is of major importance for their family members, as it makes genetic testing and prediction of cancer risk available for persons at risk. Predictive genetic testing opens up a new dimension in relationship between patients and physicians. Test results are of great importance for future plans of a person at risk, therefore predictive genetic testing should never be performed without genetic counselling. Accordingly the German Bundesärztekammer has worked out guidelines for predictive genetic testing in hereditary tumours.

Adenomatous Polyposis Coli↗
PubMed2001

Tryptophan hydroxylase polymorphism and suicidality in unipolar and bipolar affective disorders: a multicenter association study.

BACKGROUND: Being the rate-limiting enzyme in the biosynthesis of serotonin, the tryptophan hydroxylase gene (TPH) has been considered a possible candidate gene in bipolar and unipolar affective disorders (BPAD and UPAD). Several studies have investigated the possible role of TPH polymorphisms in affective disorders and suicidal behavior. METHODS: The TPH A218C polymorphism has been investigated in 927 patients (527 BPAD and 400 UPAD) and their matched healthy control subjects collected within the European Collaborative Project on Affective Disorders. RESULTS: No difference of genotype distribution or allele distribution was found in BPAD or UPAD. No statistically significant difference was observed for allele frequency and genotypes counts. In a genotype per genotype analysis in UPAD patients with a personal history of suicide attempt, the frequency of the C-C genotype (homozygosity for the short allele) was lower in UPAD patients (24%) than in control subjects (43%) (chi(2) = 4.67, p =.03). There was no difference in allele or genotype frequency between patients presenting violent suicidal behavior (n = 48) and their matched control subjects. CONCLUSIONS: We failed to detect an association between the A218C polymorphism of the TPH gene and BPAD and UPAD in a large European sample. Homozygosity for the short allele is significantly less frequent in a subgroup of UPAD patients with a history of suicide attempt than in control subjects.

Alleles↗
PubMed2001

Nonreplication of association between mu-opioid-receptor gene (OPRM1) A118G polymorphism and substance dependence.

In the present investigation we hypothesized the A118G (Asn40Asp) polymorphism of the mu-opioid receptor gene (OPRM1) as a particular vulnerability factor for heroin and alcohol dependence. Therefore, we tested this hypothesis in two independent large samples by two different methods: a case-control sample (comprising n = 287 heroin and n = 221 alcohol study subjects versus n = 365 nondependent controls) and a family-controlled sample of 111 parent-offspring trios of heroin-dependent study subjects and 75 parent-offspring trios of alcohol-dependent study subjects to avoid stratification artifacts. In both patient samples and by both methods we were unable to corroborate the hypothesis of OPRM1 A118G polymorphism as a particular risk factor for any kind of substance dependence including opioid addiction. In addition, there was no significant association between the endophenotype of the individuals under study (e.g., comorbidity, severity of illness) and a particular genotype of OPRM1.

Adenine↗
PubMed2001

The voltage-gated sodium channel gene SCN2A and idiopathic generalized epilepsy.

We tested the hypothesis that genetic variation in the human sodium channel gene SCN2A confers liability to idiopathic generalized epilepsy (IGE). We performed a systematic search for mutations in 46 familial IGE cases and detected three novel polymorphisms, however, allele frequencies did not differ significantly between patients and controls. A rare mutation (R1918H) was identified in one patient but was absent in one further affected family member. Thus, our results do not suggest a major role of SCN2A in the etiology of IGE.

Alleles↗
PubMed2001

Mutations in CAV3 cause mechanical hyperirritability of skeletal muscle in rippling muscle disease.

Hereditary rippling muscle disease (RMD) is an autosomal dominant human disorder characterized by mechanically triggered contractions of skeletal muscle. Genome-wide linkage analysis has identified an RMD locus on chromosome 3p25. We found missense mutations in positional candidate CAV3 (encoding caveolin 3; ref. 5) in all five families analyzed. Mutations in CAV3 have also been described in limb-girdle muscular dystrophy type 1C (LGMD1C; refs. 6,7), demonstrating the allelism of dystrophic and non-dystrophic muscle diseases.

Caveolin 3↗
PubMed2001

Association study of the low-activity allele of catechol-O-methyltransferase and alcoholism using a family-based approach.

Catechol-O-methyltransferase (COMT) is a major component of the metabolic pathways of neurotransmitters such as dopamine, adrenaline, and noradrenaline. The activity of COMT is known to vary within the population; it exists in common high- and low-activity forms that are determined by a Val --> Met polymorphism at amino acid position 108/158 (in soluble or membrane-bound COMT). Recently, the low-activity allele was reported to contribute to the development of late-onset alcoholism in men. The present study extends this study by utilizing a family-based association approach, and by including individuals with early-onset alcoholism. Although no significant transmission disequilibrium was found in the overall sample of 70 parent/offspring trios (TDT = 1.43, P = 0.23), we observed a preferential transmission of the low-activity allele to patients with an early onset of disease (n = 32, TDT = 4.83, P = 0.028). Our results provide further evidence for an involvement of the COMT low-activity allele in the development of alcoholism and demonstrate the need for further studies in large samples of alcoholic patients.

Adult↗
PubMed2001

A possible susceptibility locus for bipolar affective disorder in chromosomal region 10q25--q26.

In an attempt to identify susceptibility loci for bipolar affective disorder, we are currently conducting a systematic genome screen with highly polymorphic microsatellite markers at an average marker spacing of 10 cM in a series of 75 families, comprising 66 families from Germany, eight families from Israel, and one family from Italy. The families were ascertained through index cases with bipolar affective disorder. The distribution of diagnoses is as follows: 126 individuals with bipolar I disorder, 40 with bipolar II disorder, 14 with schizoaffective disorder of the bipolar type, 40 individuals with recurrent unipolar depression, 51 with a minor psychiatric diagnosis, and two individuals with a diagnosis of schizophrenia. One hundred and seventy-one individuals are unaffected. Here, we present results from chromosome 10. Linkage analyses using a total of 33 microsatellite markers with parametric and non-parametric methods provided evidence for linkage at chromosomal region 10q25--q26. The highest two-point LOD score (2.86, theta = 0.05) was obtained for D10S217 using a dominant genetic model and a broad definition of affection status. The GENEHUNTER program localized the putative susceptibility locus within a ca 15-cM interval between markers D10S1483 and D10S217 with a maximum NPL(all) score of 3.12 (P = 0.0013). Positive linkage findings that have been reported by two independent studies further support the hypothesis of a susceptibility gene for bipolar affective disorder on 10q25-q26.

Bipolar Disorder↗
PubMed2001

"Second hit" in sebaceous tumors from Muir-Torre patients with germline mutations in MSH2: allele loss is not the preferred mode of inactivation.

Muir-Torre syndrome is an autosomal-dominant inherited disorder predisposing to both sebaceous skin tumors and internal neoplasms. In a significant proportion of Muir-Torre syndrome patients skin tumors exhibit microsatellite instability as a hallmark of hereditary nonpolyposis colorectal cancer. Most individuals predisposed to hereditary nonpolyposis colorectal cancer harbor a germline mutation in the DNA mismatch repair genes MSH2 or MLH1. In Muir-Torre syndrome the vast majority of germline mutations have been identified in MSH2. Microsatellite instability in tumor tissue develops after somatic inactivation of the corresponding second mismatch repair allele ("second hit"). So far, the mechanisms of somatic inactivation of the second allele in microsatellite instability positive tumors from patients with known mismatch repair germline mutations are not well understood. We examined whether allele loss (loss of heterozygosity) is a frequent mechanism for inactivation of the second MSH2 allele in a sample of nine microsatellite instability positive skin tumors from eight unrelated Muir-Torre patients with known MSH2 germline mutations. Loss of heterozygosity was determined using microsatellite markers or heteroduplex analysis, respectively. Only one of the nine skin tumors exhibited loss of heterozygosity at the MSH2 locus. Thus, we could show in a sample of sebaceous tumors from patients with genetically proven Muir-Torre syndrome that loss of heterozygosity most probably is not the preferred mode of somatic inactivation of the second MSH2 allele.

Adult↗