DNA Lactose Intolerance Test
Fee Schedule for Year 2019
|Test Type||Testing Time||Fee|
|DNA Lactose Intolerance Test||2 to 4 weeks||RM1780Order Kit|
All orders received before 2pm are shipped out the same business day. All orders received after 2pm or on weekends or holidays are shipped out the following business day. 24/7 online status check and account management available for all tests.
Lactose is the sugar found in dairy products. It is digested by the lactase enzyme produced in the small intestine. Lactase breaks down lactose into two smaller and more readily absorbable sugars – glucose and galactose. Most mammals produce high levels of the lactase enzyme as infants, and then lactase production decreases fater weaning.
However, due to our reliance on dairy products as a food source, many humans now have lactase persistence, where the lactase enzyme is continually produced throughout adulthood.These lactase persistent individuals can digest lactose throughout their lifetime.
What is lactose intolerance?
Lactose intolerance is caused by the decreased production of the lactase enzyme. Undigested lactose builds up in the large intestine, resulting in the growth of gas-producing gut bacteria, which contribute to the symptoms of lactose intolerance, including bloating, flatulence, diarrhea, nausea and abdominal pain.
Lactose intolerance may result from a temporary reduction of lactase levels (e.g. after surgery or short-term illness), a permanent reduction due to a lifelong disease (e.g. cystic fibrosis) or due to genetic variation. The DNA Lactose Intolerance Test identifies individuals who carry a genetic variation that permanently reduces lactase production. Lactose intolerance is not the same as a dairy allergy. Individuals who are allergic to dairy will have an immune response (an allergic reaction) against milk proteins, whereas lactose intolerance is a digestive disorder.
Lactose intolerance occurs in more than 95% of Native Americans and 90% of Asians. Only 25% of Caucasians around the world, and approximately 5% of people of Northern European ancestry are lactose intolerant.
What genetic variations distinguish between lactose intolerance and lactase persistence?
Five common genetic changes that occer near the MCM6 gene allow for lactase persistence. The MCM6 gene encodes a protein that controls the production of other proteins, including lactase, which is encoded by the nearby LCT gene.
Genetic changes in the MCM6 gene result in the increased production of lactase, and first appeared when humans became more reliant on dairy as a food source. The changes have been strongly selected for in populations that consume more dairy products.
How is lactose intolerance and lactase persistence inherited?
The LCT (lactase) and MCM6 (regulatory protein) genes are located on chromosome two, one of the autosomal chromosomes. Autosomal chromosomes are inherited in pairs – one from each parent.
If an individual inherits two copies of the normal MCM6 gene, they will be lactose intolerant in adulthood and will pass this wild type gene to the next generation. If an individual inherits two copies of the variant MCM6 gene, they will have lactase persistence and will pass this lactase persistence to the next generation. If an individual has one copy of a normal MCM6 gene and one copy of a variant MCM6 gene, they usually have lactase persistence (although there may be some lactose sensitivity).
This pattern of inheritance is referred to as autosomal dominant as only one copy of the variant gene is required to provide the lactase persistence.
DNA testing for lactose intolerance and lactase persistence
A simple DNA test can be completed to determine which versions of the MCM6 gene an individual has inherited. The DNA test provided by this laboratory examines these five markers that are associated with lactose intolerance (normal) or lactase persistence (variant).
- rs41525747, -13907C>G
- rs4988235, -13910C>T
- rs41380347, -13915T>G
- rs145946881, -14010G>C
- rs182549, -22018G>A