Molecular Genetics of Lactase Deficiencies

Congenital lactase deficiency (CLD) (MIM 223000) is a rare autosomal recessive gastrointestinal disorder characterized by watery diarrhea in infants fed with breast milk or other lactose-containing formulas. The CLD locus was previously assigned by linkage and linkage disequilibrium analyses on 2q21 in 19 Finnish families. In this study, the molecular background of this disorder is reported. The CLD locus was refined in 32 CLD patients in 24 families by using microsatellite and single nucleotide polymorphism (SNP) haplotypes. Mutation analyses were performed by direct sequencing. We identified 5 distinct mutations in the lactase (LCT) gene, encoding the enzyme that hydrolyzes lactose in the intestinal lumen. These findings facilitate genetic testing of CLD in clinical practice and enable genetic counseling. The present data also provide the basis for detailed characterization of the molecular pathogenesis of this disorder. Adult-type hypolactasia (MIM 223100) (lactase non-persistence, lactose intolerance) is an autosomal recessive gastrointestinal condition that is a result of a decline in the activity of lactase in the intestinal lumen after weaning. Adult-type hypolactasia is considered to be a normal phenomenon among mammals and symptoms are remarkably milder than experienced in CLD. Recently, a variant C/T-13910 was shown to associate with the adult-type hypolactasia trait, locating 13.9 kb upstream of the LCT gene. In this study, the functional significance of the C/T-13910 variant was determined by studying the LCT mRNA levels in intestinal biopsy samples in children and adults with different genotypes. RT-PCR followed by solid-phase minisequencing was applied to determine the relative expression levels of the LCT alleles using an informative SNP located in exon 1. In children, the C-13910 allele was observed to be downregulated after five years of age in parallel with lactase enzyme activity. The expression of the LCT mRNA in the intestinal mucosa in individuals with the T-13910 A-22018 alleles was 11.5 times higher than that found in individuals with the C-13910, G-22018 alleles. These findings suggest that the C/T-13910 associated with adult-type hypolactasia is associated with the transcriptional regulation of the LCT gene. The presence of the T-13910 A-22018 allele also showed significant elevation lactase activity. Galactose, the hydrolysing product of the milk sugar lactose, has been hypothesized to be poisonous to ovarian epithelial cells. Hence, consumption of dairy products and lactase persistence has been proposed to be a risk factor for ovarian carcinoma. To investigate whether lactase persistence is related to the risk of ovarian carcinoma the C/T-13910 genotype was determined in a cohort of 782 women with ovarian carcinoma 1331 individuals serving as controls. Lactase persistence did not associate significantly with the risk for ovarian carcinoma in the Finnish, in the Polish or in the Swedish populations. The findings do not support the hypothesis that lactase persistence increases the risk for ovarian carcinoma.

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The purpose of the research was to determine how well Finnish children and youngsters in different ages recognize poisonous and eatable wild plant species and to which characteristics they pay attention to when identifying plants. The purpose was also to find out, how well the pupils and students can estimate if the wild plants are either poisonous or eatable. The goal was to gather knowledge about what factors explain these recognition and estimation skills. Also information was wanted about attitudes of children and youngsters towards recognizing and learning the poisonous and eatable wild plants. The research was made on subjects of 48 children and youngsters from grade 6 in primary school, grade 8 in lower- secondary school and vocational school. Both quantitative and qualitative methods were used. A plant recognition test, where 38 pictures on plants was presented, was made for the all subjects. The subjects were requested to name the plants and classify them to be either poisonous or eatable. In addition six students were interviewed from each class, altogether 18 subjects. The themes of the interviews were the attitudes towards eatable and poisonous wild plants and to learn to recognize species. During the interview pictures of plants were looked at and the subjects told which characteristics they pay attention to when trying to recognize it. The results showed that on average wild plants were recognized insufficiently. Standard variation in responses was large in all classes researched. The subjects got better results in classifying of the plants to be either poisonous or eatable than in naming the plants. This research shows that even when a subject cannot name a plant it is still possible for the subject to classify the plant to be either poisonous or eatable. Gender and being an immigrant explained the recognition skills of poisonous and eatable plants so that girls were somewhat better to recognize plant species and native Finns recognized poisonous and eatable plants better that immigrants. Age did not explain the skills to recognize species directly, since students in lower- secondary school recognized the poisonous and eatable plants better than primary school and vocational school students. In skills to estimate plants poisonous or eatability there was no difference according to gender, age, or immigrant background. The subjects considered the skills to recognize poisonous and eatable plants important. Learning to recognize plants at school was not considered interesting however. Since the recognition of plants in neighborhood belongs to tasks of general education it is important to think about how the teaching could be made interesting. According to findings of this study, especially the recognition of poisonous plants was considered important by the subjects. This knowledge as well as teaching about possibilities to utilize plants could be used as a way to motivate and teach the students. Avainsanat Nyckelord - Keywords Plant species recognition, recognition of poisonous plants, recognition of eatable plants, plant species education