Galactosemia Gene Mutation Detection - Test, Procedure & Cost

Galactosemia: Autosomal recessive disorder

It is an inherited metabolic disorder of carbohydrates that occurs due to a deficiency of 1 of the four enzymes galactose-1-phosphate uridyltransferase, galactokinase, uridine diphosphate galactose-4-epimerase, and galactose mutarotase.

There are four types of galactosemia

1. Classic galactosemia-due mutation in the GALT gene
2. Galactokinase deficiency-due to a mutation in the GALK gene
3. Galactose epimerase-due to a mutation in the GALE gene
4. Duarte galactosemia-due to a mutation in the GALT gene (same as in classic galactosemia, but less severe mutation)

The increased plasma concentration of galactose which leads to its manifestations-

• Loss of appetite.
• Lethargy.
• Vomiting.
• Diarrhea.
• Severe weight loss.
• Weakness.
• Failure to thrive.
• Jaundice.
• Enlarged liver.
• Abdominal swelling 

Complications

If galactosemia is not treated at its early stage, it leads to further complications such as liver failure, cirrhosis, intellectual disability, cataract splenomegaly, tremors, shock, learning disability, speech problems and delays, and low bone mineral density. They have an increased risk of Escherichia coli sepsis.

Females affected with galactosemia show premature ovarian insufficiency.

Materials and Methods

DNA prepared ration-Using allele-specific cleavage assay, specimens containing N314D, Q188R, S135L, and K285N mutations were identified during routine newborn galactosemia screening.DNA collected from dried blood specimens is used as tests for template

Amplification and hybridization probes.

How is it done?

Galactosemia screening is done by analyzing total galactose or by measuring the GALT gene activity. This approinfluentialfective but environmental factors and mutation in Duarte D2  mutation lead to false positive results.

A panel of five assays is performed on DNA derived from newborn dried blood specimens to fourteen four most common alleles associated with classic galactosemia. These assays are easy inter——nationally results insults in a decline of false positive results.

Classic galactosemia is also known as type -1 galactosemia; it occurs from a mutation in both less of the GALT gene. The Duarte N314D mutation, when paired with the h type-1 galactosemia allele, results in the milder and probably benign D/G phenotype with a nearly 75% decline in enzyme activity. Biochemicadatthat generated by a D/G mixed heterozygote mimics classical galactosemia in the newborn period, leading to a false positive result.