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MTHFR is the rate-limiting enzyme in the methyl cycle, which includes the conversion of homocysteine into methionine. Defects in variants of MTHFR can therefore lead to hyperhomocysteinemia. [9] There are two common variants of MTHFR deficiency. In the more significant of the two, the individual is homozygous for the 677T polymorphism.
Some mutations in this gene are associated with methylenetetrahydrofolate reductase deficiency. [6] [7] [8] Complex I deficiency with recessive spastic paraparesis has also been linked to MTHFR variants. In addition, the aberrant promoter hypermethylation of this gene is associated with male infertility and recurrent spontaneous abortion. [9] [10]
Haemochromatosis is protean in its manifestations, i.e., often presenting with signs or symptoms suggestive of other diagnoses that affect specific organ systems.Many of the signs and symptoms below are uncommon, and most patients with the hereditary form of haemochromatosis do not show any overt signs of disease nor do they have premature morbidity, if they are diagnosed early, but, more ...
The CDKN2A gene is located on chromosome 9p21.3. Two main transcripts, isoforms '1' and '4', each contain three exons and span 7288 and 26740 bp, respectively. They encode proteins of 156 and 173 amino acids; isoform '1' encodes p16(INK4a), while isoform '4' encodes p14(ARF), a protein that is structurally unrelated to p16(INK4) but acts in cell cycle G1 control by stabilizing the tumor ...
Majority of the cases of hemochromatosis are caused by mutations in the HFE (Homeostatic Iron Regulator) gene. [17] Type 3 HH is characterized by compound heterozygote mutations in both transferrin receptor 2 (TFR2) and HFE, i.e. a single mutation in each gene. HFE is located on chromosome 6 and TFR2 is located on chromosome 7.
Co-expression of this mutation and the 677T polymorphism in methionine tetrahydrofolate reductase (MTHFR) Methylenetetrahydrofolate reductase act to further the extent of DNA damage. [ 36 ] Hypomethylation due to impaired methylation up regulates atherosclerotic susceptible genes whilst down regulating atherosclerosis protective genes. [ 36 ]
Duchenne muscular dystrophy is caused by a mutation of the dystrophin gene, located on the short arm of the X chromosome (locus Xp21) [22] that codes for dystrophin protein. Mutations can either be inherited or occur spontaneously during germline transmission, [ citation needed ] causing a large reduction or absence of dystrophin, a protein ...
It almost always occurs as a new mutation, with less than one percent of cases being inherited. [4] [5] It occurs almost exclusively in girls; [4] boys who have a similar mutation typically die shortly after birth. [5] Diagnosis is based on the symptoms and can be confirmed with genetic testing. [5] There is no known cure for Rett syndrome. [5]