Original Article
European Journal of Clinical Nutrition (2007) 61, 1220–1225; doi:10.1038/sj.ejcn.1602638; published online 21 February 2007
Genetic testing improves the diagnosis of adult type hypolactasia in the Mediterranean population of Sardinia
Guarantor: E Schirru.
Contributors: ES participated in the genotyping of the DNA variant, designing and drawing the paper and approved the final version. VC participated in the genotyping of the DNA variant, designing and drawing the paper and approved the final version. PUS participated in performing the breath test, in designing and drawing the paper and approved the final version. MS participated in performing the breath test and designing the paper approved the final version. FO participated in designing the paper and in collecting the bibliography and approved the final version. FLI participated in designing the paper and in selecting subjects negative and positive at the lactose breath hydrogen test with 25 g of lactose and approved the final version. FC participated in designing the paper and in statistical analysis and approved the final version. SDeV participated in designing the paper and in collecting the bibliography and approved the final version. RR participated in performing cloning, sequencing and designing the paper and approved the final version. MDM participated in performing cloning, sequencing and designing of the paper and approved the final version. RDJ participated in designing and drawing the paper and approved the final version. MC participated in genotyping the DNA, designing and drawing the paper and approved the final version.
E Schirru1, V Corona1, P Usai-Satta2, M Scarpa2, F Oppia2, F Loriga2, F Cucca3, S De Virgiliis1, R Rossino1, M Doloretta Macis1, R-D Jores1 and M Congia1
- 1Biomedical Science and Biotechnologies, University of Cagliari, Via Jenner, Cagliari, Italy
- 2Struttura complessa di Gastroenterologia, Azienda Ospedaliera Brotzu, Via Peretti, Cagliari, Italy
- 3Biomedical Scienze, University of Sassari, Viale S. Pietro.43, Sassari, Italy
Correspondence: Dr M Congia, Biomedical Science and Biotechnologies, University of Cagliari, Via Jenner, 09121 Cagliari, Italy. E-mail: mcongia@mcweb.unica.it
Received 3 May 2006; Revised 30 November 2006; Accepted 30 November 2006; Published online 21 February 2007.
Abstract
Objective:
Recently, the C/T-13910 polymorphism on chromosome 2q21 in North-European populations has been found completely associated with lactase activity and its genetic typing proposed as first-stage screening test for adult hypolactasia. However, the C/T-13910 variant in some sub-Saharan African groups is not a predictor of lactase persistence. In this work, we wanted to verify if in the Mediterranean island of Sardinia, located in Southern Europe, the C/T-13910 polymorphism may be useful or not for the diagnosis of adult type hypolactasia.
Design:
Validation study of a genetic testing for adult type hypolactasia in Sardinians.
Setting:
Brotzu Hospital and Microcitemico Hospital, Cagliari, Italy.
Subjects:
The sample consisted in 84 Sardinian individuals (63 women and 21 men; range 20–73 years) selected from a group of 832 patients.
Methods:
Genetic testing was compared to an improved test obtained by a combination of different breath hydrogen tests and clinical assessment.
Results:
We found that all 49 individuals with lactose malabsorption, demonstrated by a combination of different breath hydrogen tests and clinical assessment, carried the C/C-13910 genotype associated with lactase non-persistence, 23 individuals with lactose normal absorption carried the C/T-13910 genotype associated with lactase persistence and only one person with the above phenotype showed a discordant C/C-13910 genotype. The genetic testing showed very high sensitivity, specificity, positive and negative predictive values of 100, 95.8, 98 and 100%, respectively.
Conclusions:
Sardinians, unlike some ethnic groups in sub-Saharan Africa, show the same genetic association of hypolactasia with the C/T-13910 variant as other North-European populations. The genetic testing for the C/T-13910 variant may contribute to improving the diagnosis of adult type hypolactasia.
Keywords:
breath test, genotype, lactose malabsorption, lactase, RFLP
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