Introducing genetic testing for adult-type hypolactasia

Area of Science:

• Genetics
• Gastroenterology
• Molecular Diagnostics

Background:

• Adult-type hypolactasia is a common cause of lactose intolerance.
• Diagnosis often relies on symptomatic presentation and functional tests like the H2 breath test.
• Genetic variants associated with hypolactasia are increasingly recognized.

Purpose of the Study:

• To evaluate the diagnostic utility of genotyping two specific DNA variants (c.1993+327C>T and c.1438+117G>A) for adult-type hypolactasia.
• To compare the accuracy of genetic testing with the standard hydrogen (H2) breath test.
• To assess the role of these variants in the diagnosis of lactose intolerance.

Main Methods:

• Inclusion of 166 consecutive patients with gastrointestinal symptoms suggestive of hypolactasia.
• Performance of DNA genotyping for variants c.1993+327C>T and c.1438+117G>A.
• Comparison of genotyping results with the standard H2 breath test.

Main Results:

• The c.1993+327C variant was detected in 91.4% of patients with a positive H2 breath test and in 4% of those with a negative test.
• Genotyping for c.1993+327C demonstrated high sensitivity (91.4%) and specificity (96.0%).
• Genotyping for c.1438+117G provided no additional diagnostic information; other conditions caused hypolactasia in some cases.

Conclusions:

• Genotyping for the c.1993+327C DNA variant is a highly sensitive and specific test for adult-type hypolactasia.
• This genetic test offers a reliable new tool for diagnosing hypolactasia in symptomatic individuals.
• The c.1438+117G variant was not found to be a significant diagnostic marker in this study.