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This mutation is associated with diverse health issues, however H63D syndrome is the only known specific expression of a homozygous HFE-H63D mutation to date. The homozygous HFE-H63D mutation is the cause of classic and treatable hemochromatosis in only 6.7% of its carriers. [25] H63D syndrome is independently a distinct entity, and the ...
The worldwide prevalence rates for H63D, C282Y and S65C (minor allele frequencies) are 10%, 3% and 1% respectively. [29] [30] [31] The C282Y allele is a transition point mutation from guanine to adenine at nucleotide 845 in HFE, resulting in a missense mutation that replaces the cysteine residue at position 282 with a tyrosine amino acid. [32]
In medical genetics, compound heterozygosity is the condition of having two or more heterogeneous recessive alleles at a particular locus that can cause genetic disease in a heterozygous state; that is, an organism is a compound heterozygote when it has two recessive alleles for the same gene, but with those two alleles being different from each other (for example, both alleles might be ...
[21] [22] Allele frequencies of H63D in ethnically diverse western European populations are 10-29%. [23] and in North American non-Hispanic whites are 14-15%. [24] At least 42 mutations involving HFE introns and exons have been discovered, most of them in persons with hemochromatosis or their family members. [25] Most of these mutations are rare.
This mutation, which at first glance appeared to be harmful, conferred enough of an advantage to heterozygotes to make it beneficial, so that it remained at dynamic equilibrium in the gene pool. Kalmus introduced flies with the ebony mutation to a wild-type population.
The remaining copy of the tumor suppressor gene can be inactivated by a point mutation or via other mechanisms, resulting in a loss of heterozygosity event, and leaving no tumor suppressor gene to protect the body. Loss of heterozygosity does not imply a homozygous state (which would require the presence of two identical alleles in the cell).
A transheterozygote is a diploid organism that is heterozygous at two different loci (genes). Each of the two loci has one natural (or wild type) allele and one allele that differs from the natural allele because of a mutation.
Hemoglobin variants occur when there are mutations in specific genes that code for the protein chains, known as globins, which make up the hemoglobin molecule. This leads to amino acid substitutions in the hemoglobin molecule that could affect the structure, properties, and/or the stability of the hemoglobin molecule.