1. ¹Institute of Genetics, Biological Research Centre of Hungarian Academy of Sciences, Szeged, Hungary
2. ²Department of Paediatrics, Albert Szent-Györgyi Medical University, Szeged, Hungary

Correspondence: Dr D Nagy, Institute of Genetics, Biological Research Centre of Hungarian Academy of Sciences, POB 521, H-6701, Szeged, Hungary. E-mail: nagydor@gmail.com

Received 10 March 2008; Revised 25 September 2008; Accepted 2 December 2008; Published online 21 January 2009.

Abstract

The prevalence of adult-type hypolactasia varies ethnically and geographically among populations. A C/T_–13910 single nucleotide polymorphism (SNP), upstream of the lactase gene, is known to be associated with lactase non-persistence. The aim of this study was to determine the prevalence of lactase-persistent and non-persistent genotypes in the Hungarian population, the age at onset and the applicability of the lactose H₂ breath test in comparison with genetic screening. The prevalence of the C/C_-13910 genotype among adults was 37%. Hypolactasia starts to appear at around 5 years of age. Over the age of 12 years, almost all of those with a C/C_-13910 genotype have lactase non-persistence. The C/C_-13910 genotype was closely associated with a positive lactose H₂ breath test in symptomatic children, whereas the lactase-persistent genotypes correlated better with a negative H₂ test in a control group. In conclusion, supplementary non-invasive breath and genotyping tests furnish a perfect clinical diagnosis.