scholarly journals Tyr is Responsible for the Cctq1a QTL and Links Developmental Environment to Central Corneal Thickness Determination

2021 ◽  
Author(s):  
Kacie J Meyer ◽  
Demelza R Larson ◽  
S Scott Whitmore ◽  
Carly J van der Heide ◽  
Adam Hedberg-Buenz ◽  
...  
Keyword(s):  
Quantitative Trait ◽  
Central Corneal Thickness ◽  
Light Exposure ◽  
Corneal Thickness ◽  
Causative Gene ◽  
Direct Function ◽  
Multiple Alleles ◽  
Albino Mice ◽  
Trait Locus ◽  
Derivatives Of

Central corneal thickness is a quantitative trait with important associations to human health. In a phenotype-driven approach studying corneal thickness of congenic derivatives of C57BLKS/J and SJL/J mice, the critical region for a quantitative trait locus influencing corneal thickness, Cctq1a, was delimited to a 10-gene interval. Exome sequencing, RNAseq, and studying independent mutations eliminated multiple candidate genes and confirmed one. Though the causative gene, Tyr, has no obvious direct function in the transparent cornea, studies with multiple alleles on matched genetic backgrounds, both in isolation and genetic complementation crosses, confirmed allelism of Tyr-Cctq1a; albino mice lacking Tyr function had thin corneas. Albino mice also had increased axial length. Because albinism exposes eyes to increased light, the effect of dark-rearing was tested and found to rescue central corneal thickness. In sum, the results point to an epiphenomenon; developmental light exposure interacts with genotype as an important determinate of adult corneal thickness.

scholarly journals Quantitative trait loci associated with murine central corneal thickness

2010 ◽  
Vol 42 (2) ◽  
pp. 281-286 ◽  
Author(s):  
Geoffrey D. Lively ◽  
Demelza Koehn ◽  
Adam Hedberg-Buenz ◽  
Kai Wang ◽  
Michael G. Anderson
Keyword(s):  
Quantitative Trait ◽  
Central Corneal Thickness ◽  
Genetic Basis ◽  
Phenotypic Variability ◽  
Corneal Thickness ◽  
Biological Significance ◽  
Chromosome 7 ◽  
Structural Support ◽  
Trait Locus ◽  
Lines Of Evidence

The cornea is a specialized transparent tissue responsible for refracting light, serving as a protective barrier, and lending structural support to eye shape. Given its importance, the cornea exhibits a surprising amount of phenotypic variability in some traits, including central corneal thickness (CCT). More than a mere anatomic curiosity, differences in CCT have recently been associated with risk for glaucoma. Although multiple lines of evidence support a strong role for heredity in regulating CCT, the responsible genes remain unknown. To better understand the genetic basis of CCT variability, we conducted a genomewide quantitative trait locus (QTL) analysis with (C57BLKS/J × SJL/J) F2mice. This experiment identified a locus, Cctq1 (central corneal thickness QTL 1) on chromosome 7 (Chr 7; peak, 105 Mb), that is significantly associated with CCT. To independently test the biological significance of these results, (C57BLKS/J × NZB/B1NJ) F2mice were generated and analyzed for associations with Chr 7. This experiment identified a significant association at 131 Mb. Furthermore, low-generation congenic mice in which the Chr 7 QTL interval from the SJL strain was transferred onto the KS background had CCT values significantly higher than inbred KS mice. These results demonstrate that the genetic dependence of CCT in mice is a multigenic trait, which in these contexts is significantly regulated by a region on Chr 7. Future identification of the genes for these QTL will provide improved understanding of the processes regulating CCT and the pathophysiology of glaucoma.

scholarly journals A classical setting for associations between markers and loci affecting quantitative traits

1999 ◽  
Vol 74 (3) ◽  
pp. 271-277 ◽  
Author(s):  
DAHLIA M. NIELSEN ◽  
B. S. WEIR
Keyword(s):  
Genetic Marker ◽  
Quantitative Trait ◽  
Quantitative Traits ◽  
Genetic Variance ◽  
Genetic Model ◽  
Marker Locus ◽  
Multiple Alleles ◽  
Classical Setting ◽  
Tests Of Association ◽  
Trait Locus

We examine the relationships between a genetic marker and a locus affecting a quantitative trait by decomposing the genetic effects of the marker locus into additive and dominance effects under a classical genetic model. We discuss the structure of the associations between the marker and the trait locus, paying attention to non-random union of gametes, multiple alleles at the marker and trait loci, and non-additivity of allelic effects at the trait locus. We consider that this greater-than-usual level of generality leads to additional insights, in a way reminiscent of Cockerham's decomposition of genetic variance into five terms: three terms in addition to the usual additive and dominance terms. Using our framework, we examine several common tests of association between a marker and a trait.

scholarly journals Evidence for Multiple Alleles at the DGAT1 Locus Better Explains a Quantitative Trait Locus With Major Effect on Milk Fat Content in Cattle

Genetics ◽  
2004 ◽  
Vol 167 (4) ◽  
pp. 1873-1881 ◽  
Author(s):  
Christa Kühn ◽  
Georg Thaller ◽  
Andreas Winter ◽  
Olaf R. P. Bininda-Emonds ◽  
Bernhard Kaupe ◽  
...  
Keyword(s):  
Quantitative Trait Locus ◽  
Quantitative Trait ◽  
Milk Fat ◽  
Major Effect ◽  
Fat Content ◽  
Multiple Alleles ◽  
Trait Locus

scholarly journals Multiple alleles for tuber shape in diploid potato detected by qualitative and quantitative genetic analysis using RFLPs.

Genetics ◽  
1994 ◽  
Vol 137 (1) ◽  
pp. 303-309 ◽  
Author(s):  
H J Van Eck ◽  
J M Jacobs ◽  
P Stam ◽  
J Ton ◽  
W J Stiekema ◽  
...  
Keyword(s):  
Qtl Mapping ◽  
Quantitative Trait ◽  
Genetic Factors ◽  
Inbred Strains ◽  
Width Ratio ◽  
Tuber Shape ◽  
Multiple Alleles ◽  
Length Polymorphisms ◽  
Trait Locus ◽  
Diploid Level

Abstract Tuber shape in potato is commonly regarded as displaying continuous variation, yet at the diploid level phenotypes can be discerned visually, having round or long tubers. Inheritance of qualitative tuber shape can be explained by a single locus Ro, round being dominant to long. With restriction fragment length polymorphisms (RFLPs) the Ro locus was mapped on chromosome 10. Tuber shape was also studied as a quantitative trait, using the length/width ratio as trait value. The estimated broad sense heritability was h2 = 0.80. The morphologically mapped Ro locus explained 75% of the genetic variation, indicating the presence of a major quantitative trait locus (QTL) at the Ro locus and minor genetic factors. RFLP alleles linked with Ro alleles were used to divide the progeny into four genotypic classes: RofemaleRomale:Rofemalero:roRomale:roro = 1:1:1:1. The recessive ro allele is identical by descent in both parents. The significantly different effects (P = 0.0157) of the non-identical alleles Rofemale and Romale provided evidence for multiallelism at the Ro locus. Linkage mapping of the Ro locus was compared with QTL mapping. Only those markers which are polymorphic in both parents allow accurate QTL mapping when genetic factors segregate from both parents. This finding applies to QTL mapping in all outbreeders without homozygous inbred strains.

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