title: Molecular genetics of human lactase deficiencies.
abstract: Lactase non-persistence (adult-type hypolactasia) is present in more than half of the human population and is caused by the down-regulation of lactase enzyme activity during childhood. Congenital lactase deficiency (CLD) is a rare severe gastrointestinal disorder of new-borns enriched in the Finnish population. Both lactase deficiencies are autosomal recessive traits and characterized by diminished expression of lactase activity in the intestine. Genetic variants underlying both forms have been identified. Here we review the current understanding of the molecular defects of human lactase deficiencies and their phenotype-genotype correlation, the implications on clinical practice, and the understanding of their function and role in human evolution.
authors.affiliation: Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland. irma.jarvela@kolumbus.fi
authors.forename: Irma
authors.initials: I
authors.lastname: Järvelä
authors.forename: Suvi
authors.initials: S
authors.lastname: Torniainen
authors.forename: Kaija-Leena
authors.initials: KL
authors.lastname: Kolho
mesh_terms: D000328:Adult; D002648:Child; D015536:Down-Regulation; D005387:Finland; D015971:Gene Expression Regulation, Enzymologic; D005838:Genotype; D006801:Humans; D043322:Lactase / Q000172:deficiency / Q000235:genetics*; D007787:Lactose Intolerance / Q000235:genetics*; D008967:Molecular Biology; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide
chemical_list: D043322:Lactase