Clinical Utility of LCT Genotyping in Children with Suspected Functional Gastrointestinal Disorder.

María L Couce,Emiliano González-Vioque,Rosaura Leis,Paula Sánchez-Pintos

doi:10.3390/nu12103017

Abstract

Genetic testing is a good predictor of lactase persistence (LP) in specific populations but its clinical utility in children is less clear. We assessed the role of lactose malabsorption in functional gastrointestinal disorders (FGID) in children and the correlation between the lactase non-persistence (LNP) genotype and phenotype, based on exhaled hydrogen and gastrointestinal symptoms, during a hydrogen breath test (HBT). We also evaluate dairy consumption in this sample. We conducted a 10-year cross-sectional study in a cohort of 493 children with suspected FGID defined by Roma IV criteria. Distribution of the C/T-13910 genotype was as follows: CC, 46.0%; TT, 14.4% (LP allele frequency, 34.1%). The phenotype frequencies of lactose malabsorption and intolerance were 36.3% and 41.5%, respectively. We observed a strong correlation between genotype and both lactose malabsorption (Cramér’s V, 0.28) and intolerance (Cramér’s V, 0.54). The frequency of the LNP genotype (p = 0.002) and of malabsorption and intolerance increased with age (p = 0.001 and 0.002, respectively). In 61% of children, evaluated dairy consumption was less than recommended. No association was observed between dairy intake and diagnosis. In conclusion, we found a significant correlation between genotype and phenotype, greater in older children, suggesting that the clinical value of genetic testing increases with age.

Highlights

The digestion of lactose, a common disaccharide in human nutrition, is dependent on intestinal lactase (LCT) activity
LCT expression begins before birth, remains high during the nursing period, and in most people, progressively declines after weaning, resulting in lactase nonpersistence (LNP) [1]
Our results show that a diagnosis of lactose malabsorption was established in about one third (36.3%) of children with recurrent abdominal pain due to suspected functional disorder

Summary

Introduction

The digestion of lactose, a common disaccharide in human nutrition, is dependent on intestinal lactase (LCT) activity This enzyme, known as lactase-phlorizin hydrolase, is a β-d-galactosidase found in the apical surface of the intestinal microvilli. LCT expression begins before birth, remains high during the nursing period, and in most people, progressively declines after weaning, resulting in lactase nonpersistence (LNP) [1]. This genetically programmed reduction in lactase activity varies greatly between populations, with lowest levels observed in Nordic populations (

Methods

Results

Conclusion