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Biomedical subjects

N Craddock

Publications and source records attributed to N Craddock.

At least 109 records · Page 6Linked to original sources
PubMed1996

Increasing the efficiency of genomic searches for linkage in complex disorders by DNA pooling of affected sib-pairs.

Detection of linkage using a systematic genome scan in nuclear families including an affected sibling pair is an important initial step on the path to cloning susceptibility genes for complex genetic disorders such as bipolar disorder and schizophrenia. We describe a novel method in which the pooled genotype of each affected sib-pair is determined and used in the screening stage of a two-stage genome scan. This method, which involves a single PCR reaction per sib-pair in the screening stage can reduce the required number of genotypings to less than 20% of those required in a conventional single stage procedure whilst maintaining a similar power and probability of type I error.

Bipolar Disorder↗
PubMed1995

No evidence for allelic association between bipolar disorder and monoamine oxidase A gene polymorphisms.

We have tested the hypothesis that DNA markers in the MAOA gene show allelic association with bipolar affective disorder. Eighty-four unrelated Caucasian patients with DSM III-R bipolar disorder and 84 Caucasian controls were typed for three markers in MAOA: a dinucleotide repeat in intron 2, a VNTR in intron 1, and an Fnu4HI RFLP in exon 8. No evidence for allelic association was observed between any of the markers and bipolar disorder.

Adult↗
PubMed1995

Association study of bipolar disorder using a functional polymorphism (Ser311-->Cys) in the dopamine D2 receptor gene.

Several pieces of evidence are consistent with the involvement of dopamine neurotransmission in the aetiology of bipolar disorder. We have tested the hypothesis that the functional mutation Ser311-->Cys of the dopamine D2 receptor gene confers susceptibility to bipolar disorder. There was no increased frequency of the mutation in 82 bipolar probands compared with 72 controls, showing that this mutation is not involved in the pathogenesis of (at least) the vast majority of cases of bipolar disorder. Our findings are consistent with other evidence from linkage and association studies against the involvement of the dopamine D2 receptor in bipolar disorder.

Alleles↗
PubMed1995

Mathematical limits of multilocus models: the genetic transmission of bipolar disorder.

We describe a simple, graphical method for determining plausible modes of inheritance for complex traits and apply this to bipolar disorder. The constraints that allele frequencies and penetrances lie in the interval 0-1 impose limits on recurrence risks, KR, in relatives of an affected proband for a given population prevalence, KP. We have investigated these limits for KR in three classes of relatives (MZ co-twin, sibling, and parent/offspring) for the general single-locus model and for two types of multilocus models: heterogeneity and multiplicative. In our models we have assumed Hardy-Weinberg equilibrium, an all-or-none trait, absence of nongenetic resemblance between relatives, and negligible mutation at the disease loci. Although the true values of KP and the KR's are only approximately known, observed population and family data for bipolar disorder are inconsistent with a single-locus model or with any heterogeneity model. In contrast, multiplicative models involving three or more loci are consistent with observed data and, thus, represent plausible models for the inheritance of bipolar disorders. Studies to determine the genetic basis of most bipolar disorder should use methods capable of detecting interacting oligogenes.

Alleles↗
PubMed1994

Variation at the fragile X locus does not influence susceptibility to bipolar disorder.

Over the last 20 years several pedigrees have been reported which are suggestive of linkage between susceptibility to bipolar disorder and markers on chromosome Xq28. Other workers have failed to replicate these reports and the methodology of the positive reports has been criticised. Recently there have been several reports of an association between fragile X (FRA(X)) and affective disorder within families and in unrelated individuals compared with controls. Such reports could be consistent with the Xq28 marker reports because FRA(X) maps to Xq27.3. We report a study at the FRA(X) CGG repeat locus in 79 unrelated Caucasian bipolar probands without fragile X syndrome and 77 unrelated controls. We found no evidence that variation at this locus confers susceptibility to bipolar disorder.

Adult↗
PubMed1994

The gene for Darier's disease maps between D12S78 and D12S79.

Darier's disease is a dominantly inherited skin disorder in which there is abnormal adhesion between keratinocytes. We and others have recently mapped the disease gene to chromosome 12q23-q 24.1. In the present study we have established that the disease gene lies between the loci D12S78 and D12S79 which are 12cM apart. We have also obtained direct evidence that the disease is unlikely to result from a mutation in one of the members of the keratin gene cluster on chromosome 12q.

Chromosome Mapping↗
PubMed1994

Association and haplotype analysis at the tyrosine hydroxylase locus in a combined German-British sample of manic depressive patients and controls.

Tyrosine hydroxylase (TH) is the key enzyme in the synthesis of catecholamines and may therefore be of aetiological relevance in the development of psychiatric illness. Hipolar affective disorder association studies, with restriction fragment length polymorphisms located in flanking regions of the TH gene, have shown conflicting results. Alleles of a tetranucleotide repeat polymorphism (TH4) located in intron 1 of the gene were tested for association with bipolar affective disorder in a combined German and British sample of 183 bipolar patients and 209 healthy control probands. No differences in TH4 allele frequencies were found in the two groups. A subset of patients and controls was typed with the flanking markers Ty7/BglII and pJ4.7/TaqI and frequencies of two-locus haplotypes were estimated. Linkage disequilibrium was found between TH4-Ty7 and TH4-pJ4.7. Haplotype frequencies did not differ between patients and controls.

Alleles↗
PubMed1994

Is there an inverse relationship between Down's syndrome and bipolar affective disorder? Literature review and genetic implications.

Several authors have suggested the existence of an inverse relationship between bipolar affective disorder and Down's syndrome (DS). The present authors have examined this hypothesis by a critical review of the literature. The present findings are consistent with a reduced rate of bipolar disorder in subjects with DS when compared with non-DS mentally retarded adults and with the general population. Thus, possession of an extra copy of chromosome 21 may confer protection against bipolar disorder. This could be the result of non-specific mechanisms or the action of a disease-modifying gene. However, the most interesting possibility is that either dominant or recessive alleles act at a major susceptibility locus for bipolar disorder on chromosome 21. Testable predictions result from the major susceptibility locus models. In order to investigate these hypotheses further, the present authors suggest the following: (1) further studies of the prevalence of bipolar disorder in DS; and (2) the reporting of all cases of bipolar disorder in trisomy 21 with details of the meiotic origin of the non-disjunction and details about affective disorder in relatives of the proband.

Alleles↗
PubMed1994

Familial cosegregation of major affective disorder and Darier's disease (keratosis follicularis)

Darier's disease is a rare autosomal dominantly inherited keratosis. This is an account of one family in which there is co-occurrence of major affective disorder and Darier's disease in five members and absence of both disorders in five members. The pedigree is consistent with genetic linkage between the Darier gene and a major autosomal dominant susceptibility locus for major affective disorder. When the Darier's disease gene has been mapped, its chromosomal location will be an interesting candidate locus for linkage studies of major affective disorder.

Adolescent↗
PubMed1994

Bipolar affective puerperal psychosis associated with consanguinity.

Most clinical and genetic evidence suggests that puerperal psychosis is closely related to bipolar affective disorder. During a linkage study of bipolar disorder we ascertained a British family in which puerperal psychosis was associated with consanguinity in three sisters. All three subjects had lifetime RDC diagnoses of bipolar I or manic disorder. An inbred brother also had bipolar I disorder. The only female member of the sibship to escape puerperal psychosis was outbred. These findings are consistent with several genetic models for bipolar disorder in this family. The most interesting possibility is a single major susceptibility locus of recessive effect. Under this assumption, the family could be used for homozygosity mapping to help localise the putative recessive locus. If other inbred families can be found in which the same putative recessive locus is operating, the power to localise the gene by homozygosity mapping would be greatly increased.

Bipolar Disorder↗
PubMed1994

Chromosomal aberrations and bipolar affective disorder.

Chromosomal abnormalities associated with bipolar disorder may help in the localisation of susceptibility genes for bipolar illness by pinpointing 'candidate' regions of the genome for further study using molecular genetic methods. We review descriptions of chromosomal abnormalities in association with bipolar and related affective disorders and evaluate their relevance for localising susceptibility genes for bipolar disorder, using standardised criteria. We found 28 reports. We identified four genomic regions of potential interest: 11q21-25; 15q11-13; chromosome 21;Xq28. It is important that clinicians are able to recognise patients who may have chromosome abnormalities which could help in the localisation of susceptibility genes for psychiatric disorders. We suggest referral for specialist investigation and karyotyping, to a psychiatric genetics research group, of any patient with functional psychosis and one or more of the following: (a) a strong family history of functional psychosis; (b) mental retardation; (c) another disease known to be caused by a single gene; or (d) congenital abnormalities.

Bipolar Disorder↗
PubMed1993

The gene for Darier's disease maps to chromosome 12q23-q24.1.

Darier's disease is a rare autosomal dominant skin disorder in which there is abnormal adhesion between keratinocytes. It appears to be associated with an increased prevalence of neuropsychiatric disorders including mental retardation and epilepsy. In addition we have previously reported a family in which major affective disorder cosegregates with Darier's disease. In the present study we have localized the gene for Darier's disease to chromosome 12q23-q24.1 by linkage analysis in five British pedigrees. We obtained a maximum two point lod score of 4.29 with marker D12S84 at zero recombination fraction. All five families showed evidence of linkage between the disease gene and markers in this region. Subsequent identification of the Darier's disease gene will provide insights into normal mechanisms of cell adhesion and may be of importance in the genetic investigation of neuropsychiatric disorders as well as elucidating the pathogenesis of Darier's disease itself.

Chromosome Mapping↗