Biomedical subjects

James Malley

Publications and source records attributed to James Malley.

4 recordsLinked to original sources

PubMed2004

A survey of ovary-, testis-, and soma-biased gene expression in Drosophila melanogaster adults.

BACKGROUND: Sexual dimorphism results in the formation of two types of individuals with specialized reproductive roles and is most evident in the germ cells and gonads. RESULTS: We have undertaken a global analysis of transcription between the sexes using a 31,464 element FlyGEM microarray to determine what fraction of the genome shows sex-biased expression, what tissues express these genes, the predicted functions of these genes, and where these genes map onto the genome. Females and males (both with and without gonads), dissected testis and ovary, females and males with genetically ablated germlines, and sex-transformed flies were sampled. CONCLUSIONS: Using any of a number of criteria, we find extensive sex-biased expression in adults. The majority of cases of sex differential gene expression are attributable to the germ cells. There is also a large class of genes with soma-biased expression. There is little germline-biased expression indicating that nearly all genes with germline expression also show sex-bias. Monte Carlo simulations show that some genes with sex-biased expression are non-randomly distributed in the genome.

Animals↗

PubMed2004

Immunogenetic differences between Caucasian women with and those without silicone implants in whom myositis develops.

OBJECTIVE: To determine whether patients in whom myositis develops after they receive silicone breast implants have distinct clinical, serologic, and/or immunogenetic features compared with patients with myositis who do not have silicone implants. METHODS: A preliminary case series study was followed by a larger, independent, matched case-control study to evaluate women in whom myositis developed after they received silicone implants (MASI patients) compared with healthy women with silicone implants and women with myositis but without silicone implants (idiopathic inflammatory myopathy; IIM patients). RESULTS: In a preliminary study, 11 MASI patients differed from 76 IIM patients in having an increased frequency of HLA-DQA1*0102 (odds ratio [OR] 9.8, 95% confidence interval [95% CI] 1.77-96.79) and decreased frequencies of the myositis-associated risk factor DRB1*0301 (OR 0.1 [95% CI 0.002-0.63]) and its linked allele DQA1*0501 (OR 0.2 [95% CI 0.02-0.87]). A subsequent independent, matched case-control study revealed that although clinical features and autoantibodies did not differ significantly between the MASI and IIM groups, MASI patients again had decreased frequencies of DRB1*0301 (OR 0.2 [95% CI 0.07-0.72]) and DQA1*0501 (OR 0.2 [95% CI 0.08-0.84]) compared with IIM patients. Additional comparisons between MASI patients from both studies combined (n = 37) and a larger population of IIM patients (n = 453) suggested that HLA-DQA1*0102 may be uniquely associated with MASI (OR 2.6 [95% CI 1.25-5.46]). CONCLUSION: Women in whom inflammatory myopathy develops after they receive silicone implants constitute an immunogenetically distinct group of patients with myositis. These and other data suggest that autoimmune diseases as now defined may consist of multiple distinct entities, each of which is characterized by different genes and environmental exposures.

Adult↗

PubMed2003

Importance sampling method of correction for multiple testing in affected sib-pair linkage analysis.

Using the Genetic Analysis Workshop 13 simulated data set, we compared the technique of importance sampling to several other methods designed to adjust p-values for multiple testing: the Bonferroni correction, the method proposed by Feingold et al., and naïve Monte Carlo simulation. We performed affected sib-pair linkage analysis for each of the 100 replicates for each of five binary traits and adjusted the derived p-values using each of the correction methods. The type I error rates for each correction method and the ability of each of the methods to detect loci known to influence trait values were compared. All of the methods considered were conservative with respect to type I error, especially the Bonferroni method. The ability of these methods to detect trait loci was also low. However, this may be partially due to a limitation inherent in our binary trait definitions.

Computer Simulation↗

PubMed2003

Paucity of genes on the Drosophila X chromosome showing male-biased expression.

Sex chromosomes are primary determinants of sexual dimorphism in many organisms. These chromosomes are thought to arise via the divergence of an ancestral autosome pair and are almost certainly influenced by differing selection in males and females. Exploring how sex chromosomes differ from autosomes is highly amenable to genomic analysis. We examined global gene expression in Drosophila melanogaster and report a dramatic underrepresentation of X-chromosome genes showing high relative expression in males. Using comparative genomics, we find that these same X-chromosome genes are exceptionally poorly conserved in the mosquito Anopheles gambiae. These data indicate that the X chromosome is a disfavored location for genes selectively expressed in males.

Animals↗