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At least 505 records · Page 28Linked to original sources
PubMed1973

The crossveinless polygenes in an Iowa population.

A natural population of Drosophila melanogaster was tested for the presence of crossveinless (cve) alleles over the course of a summer. Approximately 8% of the wild-caught females tested carried enough cve alleles to produce true-breeding crossveinless lines. In some cases, different isofemale lines produced identical cve strains. Also, differences were sometimes observed among independently selected cve sublines of a given isofemale line.-The cv-2 allele was found to occur with a frequency of about 1% to 2%.

Alleles↗
PubMed1977

The nature of quantitative genetic variation in Drosophila. III. Mechanism of dosage compensation for sex-linked abdominal bristle polygenes.

Seventeen lines, each homozygous for a different X chromosome but all with a common autosomal genetic blackground, were constructed and assayed for abdominal bristle number to determine whether dosage compensation operates for sex-linked genes affecting this character. --The regression coefficient of male mean on female mean using a logarithmic scale was 0.90 +/- 0.13 and the genetic regression coefficient 0.92, neither differing significantly from unity. The genetic components of variance in males and females were also very similar (0.000234 or 0.000228, respectively). These results indicate that dosage compensation is complete (or nearly so) for sex-linked genes affecting this character. The bristle scores of females did not differ in reciprocal crosses between these lines, thus dosage compensation does not operate by paternal X inactivation. --The question of an adequate scale for abdominal bristle number had to be examined during the study. A logarithmic scale appeared to be adequate for both genotypic and environmental differences.

Animals↗
PubMed1996

Phenotypic variation in Waardenburg syndrome: mutational heterogeneity, modifier genes or polygenic background?

We have identified 11 mutational changes in the PAX3 gene in patients with type 1 Waardenburg syndrome (WS1) including three in the paired domain, six within or immediately adjacent to the homeodomain and two previously described polymorphic variants in exons 2 and 6. The affected members of one family carried substitutions involving two base pairs separated by one unaltered codon. Two of the deleterious mutations were identical and three others were identical to previously reported mutations. A comparison of clinical findings in families carrying substitutions in the same codon failed to reveal conspicuous similarities. Although subtle mutation-specific effects may well exist, allelic heterogeneity clearly cannot account for within family variation. However, the striking concordance of a pair of monozygotic twins with Waardenburg syndrome (WS) and previous reports of similar pairs indicate that phenotypic variation in WS has a genetic basis. If the genetic effects are mediated by oligogenic epistasis, as studies in the mouse suggest, it may ultimately be possible to predict clinically relevant aspects of the Waardenburg phenotype.

Amino Acid Sequence↗
PubMedDate not supplied

Mapping a cave fish genome: polygenic systems and regressive evolution.

We used random amplified polymorphic DNA (RAPD) fingerprinting to generate anonymous DNA markers in the fish Astyanax mexicanus, a species with both surface and cave populations. Surface individuals are eyed and pigmented; troglobitic forms are blind and depigmented. We hybridized surface fish and Pachon population cave fish and produced a RAPD genomic map 1064 cM in length (about half the total length of the genome) that was used to screen for quantitative trait loci (QTL) for troglomorphic traits. Three QTL for reduced eye size, two for decreased numbers of melanophores, two for condition factor, and the locus for the unifactorial trait, albinism, were mapped. These factors account for an average of 46% of the variance in these traits in the backcross. The results are the first direct demonstration that troglomorphic changes in this population are multifactorial. Two closely linked pairs of QTL were found. Each consisted of a regressive and a constructive trait QTL. These close linkages are unlikely to have occurred by chance (P <.05 for each) and suggest that troglomorphic evolution might be facilitated by pleiotropy or by genetic hitchhiking.

Animals↗
PubMed1978

Adipose cellularity and body composition in polygenic obese mice as influenced by preweaning nutrition.

Male mice from a line selected for rapid postweaning growth (M16) and an unselected control (ICR) were reared from birth to 3 weeks either in litters of eight (N8) or 14 (N14). Body weight gain and feed intake of M16 mice were greater than ICR. These high rates of gain and feed intake also were extended to an older age in M16 (10 weeks) than in ICR (6 weeks). The M16 line exceeded the ICR line and N8 mice exceeded N14 for fat, lean, ash, and live body weights at 4, 6, 10, 16, and 30 weeks of age. Fat percentage was greater in N8 than N14 for both ICR and M16. The adipose cellularity of the epididymal fat pads of M16 indicated a hypertrophic-hyperplastic form of obesity at 10, 16, and 30 weeks. Within each line, the N14 mice had fewer and slightly smaller fat cells than N8. However, M16-N14 mice still had considerably more and larger fat cells than ICR-N8. Restriction of energy intake from birth to 3 weeks reduced subsequent feed intake and degree of obesity. After 4 weeks, the genetic effect exerted a greater influence on the development of obesity than the preweaning nutritional regimen.

Adipose Tissue↗
PubMed2002

The role of PC-1 and ACE genes in diabetic nephropathy in type 1 diabetic patients: evidence for a polygenic control of kidney disease progression.

BACKGROUND: The DD genotype of the ACE gene predisposes to faster diabetic nephropathy (DN) progression but its role in DN development is more controversial. We reported previously, in type 1 diabetic patients, an association between faster DN progression and the PC-1 gene Q121 variant, which associates with insulin resistance in non-diabetic subjects. We investigated here whether the combination of the ACE DD genotype and the PC-1 Q121 variant predicts the development and/or progression of DN in type 1 diabetic patients. METHODS: Type 1 diabetic patients either with (n=159) or without (n=122) nephropathy were evaluated in a cross-sectional study. DN was defined as the presence of microalbuminuria or persistent proteinuria in a subject with more than 10-year duration of disease and concomitant diabetic retinopathy, and with no evidence of heart failure or other renal disease. Seventy-five (47 male/28 female) type 1 diabetic patients with nephropathy in whom retrospective information with repeated measurements of serum creatinine was available, were analysed in a longitudinal study. RESULTS: No association of the PC-1 Q121 variant and the ACE D/D genotype with DN development was observed. However, the ACE DD genotype and the PC-1 Q121 variant were associated, both independently (P=0.02 and P=0.025, respectively) or in combination (P=0.02), with a faster rate of glomerular filtration rate decline. An interaction (P=0.03) was observed between the two genes in increasing the individual patient's risk of being a fast progressor. CONCLUSION: Our data suggest that, in type 1 diabetic patients, the ACE and the PC-1 genes interact in increasing the individual risk of having a faster DN progression.

Adult↗
PubMed1999

Genetic markers to predict polygenic disease: a new problem for social genetics.

Many genetic markers that relate to common multifactorial disease in adults have been identified during the past 15 years. Their use as adjuncts for the diagnosis, prognosis, prediction of disease or targeting therapy for these disorders has begun, good examples being the Factor V Leiden mutation for venous-thromboembolism, lipoprotein lipase mutations for hypertriglyceridaemia and the apolipoprotein E4 variant for Alzheimer's dementia. However, extensive gene-gene and gene-environment interactions make their use more complex than markers for the simpler monogenic disorders (such as cystic fibrosis, or Duchenne's muscular dystrophy). Possible misapplication of the genetic markers for multifactorial disease in the fields of risk prediction, direct sales to the public, life assurance, employment rights, and legislation for regulation of their use are discussed.

Adult↗