A genetic test which can be used to diagnose adult-type hypolactasia in children
- H Rasinperä1,
- E Savilahti2,
- N S Enattah1,
- M Kuokkanen1,
- N Tötterman2,
- H Lindahl2,
- I Järvelä3,
- K-L Kolho2
- 1Department of Medical Genetics, University of Helsinki, Finland
- 2Hospital for Children and Adolescents, University of Helsinki, Finland
- 3HUSLAB, Laboratory of Molecular Genetics, Helsinki, Finland
- Correspondence to:
Dr K-L Kolho
Hospital for Children and Adolescents, Box 281, 00290 Helsinki, Finland;
- Accepted 19 April 2004
Background/Aims: Adult-type hypolactasia (primary lactose malabsorption) affects most of world’s human population and limits the use of fresh milk due to lactose intolerance. The diagnosis of adult-type hypolactasia has been difficult to establish because of unsatisfactory diagnostic methods. C/T-13910 single nucleotide polymorphism residing 13910 base pairs from the 5′ end of the lactase gene has been shown to be associated with lactase persistence. The aim of the study was to assess the applicability of the C/T-13910 variant as a diagnostic test for adult-type hypolactasia during childhood.
Methods: Intestinal biopsies were obtained from 329 children and adolescents of African, Finnish, and other White origins aged 0.1–20 years undergoing upper gastrointestinal endoscopy because of abdominal complaints. The biopsies were assayed for lactase, sucrase, and maltase activity and genotyped for the C/T-13910 variant using polymerase chain reaction minisequencing.
Results: The frequency of the C/C-13910 genotype defining lactase non-persistence was well in agreement in this study with published figures for the prevalences of adult-type hypolactasia in Africans and Whites. The C/C-13910 genotype was associated with very low lactase activity (<10 U/g protein) in the majority of children tested at 8 years of age and in every child older than 12 years of age giving a specificity of 100% and sensitivity of 93% for the genetic test. The decline of lactase activity was somewhat earlier in African compared with Finnish children with C/C-13910 genotype (p<0.03).
Conclusions: Genetic test of C/T-13910 polymorphism can be used as a first stage screening test for adult-type hypolactasia.
- CLD, congenital lactase deficiency
- LM, lactose malabsorption
- LPH, lactase-phlorizin hydrolase
- LTT, lactose tolerance test
- L:S, lactase:sucrase
- PCR, polymerase chain reaction
- SNP, single nucleotide polymorphism
- adult-type hypolactasia
- primary lactose malabsorption
- genetic testing
- PCR minisequencing
- disaccharidase activities
Funding: The Sigrid Jusélius Foundation, Helsinki, Finland, The Helsinki University Hospital Research Funding, Helsinki, Finland and The Helsinki University Science Foundation, Helsinki, Finland
Competing interests: the authors declare that they have no competing financial interests.