Decline of lactase activity and C/T-13910 variant in sardinian childhood

Objectives: Our study aims to determine the age of onset of adult-type hypolactasia in Sardinians, and to establish the age at which genotyping of the C/T-13910 variant can be used reliably in the diagnosis of lactose malabsorption. Patients and Methods: A lactose breath hydrogen test was given to 383 randomly selected patients, from 3 to 19 years old. Results: The C/C-13910 genotype was found in 90% of patients; the frequency of the positive lactose breath hydrogen test increased with age and reached a prevalence of 85% at 9 years. Conclusions: In Sardinians, adult-type hypolactasia becomes phenotypically evident in all individuals older than 9 years, suggesting that this should be considered the minimum age at which the genetic test for lactase nonpersistence should be applied. JPGN 45:503-506, 2007.