title: Decline of lactase activity and c/t-13910 variant in Sardinian childhood.
abstract: OBJECTIVE
  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.
  
  
  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.
authors.affiliation: Department of Pediatric Science and Clinical Medicine, University of Cagliari, Cagliari, Italy. schirrue@yahoo.it
authors.forename: Enrico
authors.initials: E
authors.lastname: Schirru
authors.forename: Valeria
authors.initials: V
authors.lastname: Corona
authors.forename: Paolo
authors.initials: P
authors.lastname: Usai-Satta
authors.forename: Maria
authors.initials: M
authors.lastname: Scarpa
authors.forename: Francesco
authors.initials: F
authors.lastname: Cucca
authors.forename: Stefano
authors.initials: S
authors.lastname: De Virgiliis
authors.forename: Rossano
authors.initials: R
authors.lastname: Rossino
authors.forename: Fulvia
authors.initials: F
authors.lastname: Frau
authors.forename: Maria Doloretta
authors.initials: MD
authors.lastname: Macis
authors.forename: Rita-Désirée
authors.initials: RD
authors.lastname: Jores
authors.forename: Mauro
authors.initials: M
authors.lastname: Congia
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D001944:Breath Tests; D002648:Child; D002675:Child, Preschool; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D006859:Hydrogen; D007558:Italy / Q000453:epidemiology; D043322:Lactase / Q000235:genetics* / Q000378:metabolism; D007785:Lactose / Q000378:metabolism; D007787:Lactose Intolerance / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics*; D007789:Lactose Tolerance Test; D007792:Lactulose / Q000378:metabolism; D008297:Male; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D015995:Prevalence
chemical_list: D007792:Lactulose; D006859:Hydrogen; D043322:Lactase; D007785:Lactose