title: Genetic testing for adult-type hypolactasia in Italian families.
abstract: BACKGROUND
  Adult-type hypolactasia is characterized by the inability to digest lactose during adulthood, due to lactase (LCT) deficiency. It is usually diagnosed by the measurement of breath hydrogen increase after a lactose load (breath hydrogen test, BHT). A substitution of C to T at position -13910 bp upstream the LCT gene (rs4988235), in a regulatory region, was found to be strongly associated with the lactase persistence phenotype in North-European populations.
  
  
  METHODS
  We investigated the -13910 C/T polymorphism to determine LCT genotype distribution and to validate genetic testing for adult-type hypolactasia in a Southern European population. A total of 43 children referred for suspected lactose malabsorption were enrolled in the study, their parents and siblings (whole sample=112 individuals) also took the breath test, and all were enrolled for clinical monitoring and genotype determination. In addition, 125 unrelated blood donors from the same geographic area were genotyped for the calculation of allelic frequencies. The frequency of C/C genotypes was 70%.
  
  
  RESULTS
  The correlation between the C/C genotype (which should correspond to lactose non-digesters) and positive BHT in unrelated family founders was significant (chi(2)=16.7, p<0.002). The genetic test compared to the BHT had a sensitivity of 95% and 91% and a specificity of 48% and 55% in adults and children, respectively.
  
  
  CONCLUSIONS
  Low specificity might be due to intrinsic limitations of the standard BHT or to other possible mutations, although no sequence variation was found upon sequencing a 253 bp fragment of the LCT regulatory region in asymptomatic individuals.
authors.affiliation: Department of Mother and Child, Biology and Genetics, University of Verona, Verona, Italy. monica.mottes@univr.it
authors.forename: Monica
authors.initials: M
authors.lastname: Mottes
authors.forename: Francesca
authors.initials: F
authors.lastname: Belpinati
authors.forename: Monia
authors.initials: M
authors.lastname: Milani
authors.forename: Daniela
authors.initials: D
authors.lastname: Saccomandi
authors.forename: Elena
authors.initials: E
authors.lastname: Petrelli
authors.forename: Marisa
authors.initials: M
authors.lastname: Calacoci
authors.forename: Roberta
authors.initials: R
authors.lastname: Chierici
authors.forename: Pier Franco
authors.initials: PF
authors.lastname: Pignatti
authors.forename: Caterina
authors.initials: C
authors.lastname: Borgna-Pignatti
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005190:Family; D005260:Female; D005787:Gene Frequency; D005820:Genetic Testing; D005838:Genotype; D006801:Humans; D007558:Italy; D043322:Lactase / Q000172:deficiency* / Q000235:genetics; D007787:Lactose Intolerance / Q000175:diagnosis / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D012680:Sensitivity and Specificity
chemical_list: D043322:Lactase