title: Prevalence and trends in adult-type hypolactasia in different age cohorts in Central Sweden diagnosed by genotyping for the adult-type hypolactasia-linked LCT -13910C > T mutation.
abstract: OBJECTIVE
  Adult-type hypolactasia (AtH) can be diagnosed by genotyping in addition to functional tests or intestinal biopsy. The aims of this study were to estimate the prevalence of AtH by genotyping and to investigate whether AtH prevalence has changed in Sweden during the 20th century.
  
  
  METHODS
  Schoolchildren (n=690) born in 1983 and 1989, and elderly individuals (n=392) born between 1920 and 1932 were genotyped for AtH using Pyrosequencing technology.
  
  
  RESULTS
  The overall prevalence of AtH among children was 14.1%. The majority of children (92%, n=635) were Caucasians with genotype prevalences: CC, 61 (10%); CT, 259 (41%); TT, 307 (49%). The frequency of the mutated allele q was 0.300 in this cohort. The prevalence of AtH estimated from the Hardy-Weinberg equilibrium (HWE) (q 2), was 9.0% (95% CI: 6.7-11.2%). Eight percent (n=55) of the children were non-Caucasian; genotype prevalences were CC, 36 (66%); CT, 15 (27%); TT, 4 (7%). The prevalence of AtH in these children estimated from HWE was 62.5% (95% CI: 49.7-75.3%). The elderly subjects were all Caucasians. Their genotype prevalences were: CC, 20 (5%); CT, 166 (42%); TT, 206 (53%); the frequency of the mutated allele q was 0.262 and their AtH prevalence estimated from HWE was 6.8% (95% CI: 4.3-9.2%).
  
  
  CONCLUSIONS
  The overall prevalence of AtH in children (14%) was higher than previously thought. Among Caucasians, higher figures were seen in children than in the elderly (9% versus 6.8%). The prevalence thus seems to be increasing and this may be due to the immigration of both non-Caucasian and Caucasian groups with a higher prevalence of AtH.
authors.affiliation: Family Medicine Research Centre, Department of Clinical Medicine, Orebro University, Sweden. ricardo.almon@orebroll.se
authors.forename: Ricardo
authors.initials: R
authors.lastname: Almon
authors.forename: Peter
authors.initials: P
authors.lastname: Engfeldt
authors.forename: Curt
authors.initials: C
authors.lastname: Tysk
authors.forename: Michael
authors.initials: M
authors.lastname: Sjöström
authors.forename: Torbjörn K
authors.initials: TK
authors.lastname: Nilsson
mesh_terms: D000293:Adolescent; D017677:Age Distribution; D000483:Alleles; D002648:Child; D004247:DNA / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D043322:Lactase / Q000235:genetics*; D007787:Lactose Intolerance / Q000097:blood / Q000453:epidemiology / Q000235:genetics; D008297:Male; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide; D015995:Prevalence; D013548:Sweden / Q000453:epidemiology; D044465:White People
chemical_list: D004247:DNA; D043322:Lactase