title: Mild CFTR mutations and genetic predisposition to lactase persistence in cystic fibrosis.
abstract: Taking into account the reported incidence of hypolactasia in cystic fibrosis (CF) and the possible impact of milk products on nutritional status we aimed to assess the genetic predisposition to adult-type hypolactasia (ATH) and its incidence in CF. Single nucleotide polymorphism upstream of the lactase gene (LCT) was assessed in 289 CF patients. In subject with -13910C/C genotype (C/C) predisposing to ATH, hydrogen-methane breath test (BT) with lactose loading was conducted and clinical symptoms typical for lactose malabsorption were assessed. The percentage of CF patients with C/C was similar to that observed in healthy subjects (HS) (31.5 vs 32.5% ). Eleven out of 52 (24.5%) CF C/C patients had abnormal BT results. The recalculated frequency of lactose malabsorption was similar for the entire CF and HS populations (6.9 vs 7.2%). Similarly as in the control group, few CF patients have identified and linked to lactose consumption clinical symptoms. The frequency of LCT polymorphic variants in CF patients having and not having severe mutations of CFTR gene showed significant differences. The C allele was more frequent in homozygotes of the severe mutations than in patients carrying at least one mild/unknown mutation (P<0.0028) and in patients with at least one mild mutation (P < 0.0377). In conclusion, CF patients carrying mild CFTR mutations seem to have lower genetic predisposition to ATH. Lactose malabsorption due to ATH in CF is not more frequent than in the general population. Symptomatic assessment of lactose malabsorption in CF is not reliable.
authors.affiliation: Department of Physiology, Poznań University of Medical Sciences, Poznań, Poland.
authors.forename: Edyta
authors.initials: E
authors.lastname: Mądry
authors.forename: Ewa
authors.initials: E
authors.lastname: Fidler
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Sobczyńska-Tomaszewska
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Lisowska
authors.forename: Patrycja
authors.initials: P
authors.lastname: Krzyżanowska
authors.forename: Andrzej
authors.initials: A
authors.lastname: Pogorzelski
authors.forename: Łukasz
authors.initials: Ł
authors.lastname: Minarowski
authors.forename: Beata
authors.initials: B
authors.lastname: Oralewska
authors.forename: Ewa
authors.initials: E
authors.lastname: Mojs
authors.forename: Ewa
authors.initials: E
authors.lastname: Sapiejka
authors.forename: Ryszard
authors.initials: R
authors.lastname: Marciniak
authors.forename: Dorota
authors.initials: D
authors.lastname: Sands
authors.forename: Anna
authors.initials: A
authors.lastname: Korzon-Burakowska
authors.forename: Jarosław
authors.initials: J
authors.lastname: Kwiecień
authors.forename: Jarosław
authors.initials: J
authors.lastname: Walkowiak
mesh_terms: D000293:Adolescent; D000328:Adult; D000483:Alleles; D002648:Child; D003550:Cystic Fibrosis / Q000235:genetics* / Q000503:physiopathology*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics*; D005260:Female; D005787:Gene Frequency / Q000235:genetics; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005838:Genotype; D006801:Humans; D043322:Lactase / Q000235:genetics* / Q000378:metabolism*; D007787:Lactose Intolerance / Q000235:genetics; D008297:Male; D009154:Mutation / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D055815:Young Adult
chemical_list: D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D043322:Lactase