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Methylmalonic acidemia has an autosomal recessive pattern of inheritance.. Methylmalonic acidemias have an autosomal recessive inheritance pattern, which means the defective gene is located on an autosome, and two copies of the gene—one from each parent—must be inherited to be affected by the disorder.
The life expectancy of individuals with EE is less than ten years. [3] Pathophysiology. Mutations in the ETHE1 gene cause ethylmalonic encephalopathy. [7]
In malonic aciduria, malonic acid and methylmalonic acid are also elevated, which is why it used to be called combined malonic and methylmalonic aciduria. Although ACSF3 deficiency was not discovered until later, the term combined malonic and methylmalonic aciduria has now become established in medical databases for ACSF3 deficiency. [30] [31]
By calculating the malonic acid to methylmalonic acid ratio in blood plasma, malonic aciduria can be clearly distinguished from combined malonic and methylmalonic aciduria (CMAMMA) and classic methylmalonic acidemia. [13] The latter applies for both, vitamin B 12 responders and non-responders in methylmalonic acidemia. [13]
The life expectancy of patients with homocystinuria is reduced only if untreated. It is known that before the age of 30, almost one quarter of patients die as a result of thrombotic complications (e.g., heart attack). [citation needed]
Although methylmalonic acidemia has a variety of causes, both genetic and dietary, methylmalonyl CoA mutase deficiency is an autosomal recessive genetic disorder. Patients with the deficiency either have a complete gene lesion, designated as mut0 or a partial mutation in the form of a frameshift designated as mut-.
However, elevated methylmalonic acid levels may also be related to metabolic disorders such as methylmalonic acidemia. If elevated methylmalonic acid levels are further accompanied by elevated malonic acid levels, this may be indicative of combined malonic and methylmalonic aciduria (CMAMMA). [147]
Methylmalonic acid is elevated in 90–98% of patients with vitamin B 12 deficiency. It has lower specificity since 20–25% of patients over the age of 70 have elevated levels of methylmalonic acid, but 25–33% of them do not have B 12 deficiency. For this reason, the testing of methylmalonic acid levels is not routinely recommended in the ...