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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]
5,10-Methenyltetrahydrofolate synthetase deficiency (MTHFS deficiency) is a rare neurodevelopmental disorder caused by mutations affecting the MTHFS gene, which encodes the enzyme 5,10-Methenyltetrahydrofolate synthetase. [2] The disease starts at birth or in early infancy and presents with microcephaly, short stature, and developmental delay.
A 2007 study based on 12 cases from the Faroe Islands (where there is a relatively high incidence due to a founder effect) suggested that the outcome is often poor with early lethality. [18] More recent studies (2015) with 50 people with SUCLA2 mutations, with range of 16 different mutations, show a high variability in outcomes with a number of ...
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 ...
A variety of mutations in the TYMP gene have been discovered that lead to the onset of mitochondrial neurogastrointestinal encephalopathy syndrome. [2] The TYMP gene is a nuclear gene, however, mutations in the TYMP gene affect mitochrondrial DNA and function. [2] Mutations in this gene result in a loss of thymidine phosphorylase activity. [2]
DiGeorge syndrome is typically due to the deletion of 30 to 40 genes in the middle of chromosome 22 at a location known as 22q11.2. [3] About 90% of cases occur due to a new mutation during early development, while 10% are inherited. [7] It is autosomal dominant, meaning that only one affected chromosome is needed for the condition to occur. [7]
Mutations in the BTD gene cause biotinidase deficiency. Biotinidase is the enzyme that is made by the BTD gene. Many mutations that cause the enzyme to be nonfunctional or to be produced at extremely low levels have been identified. Biotin is a vitamin that is chemically bound to proteins. (Most vitamins are only loosely associated with proteins.)