Are there differences between patients with and without the homozygous--13910CC genetic variant in the MCM-6 gene...

Patients with chronic abdominal complaints are a diagnostic challenge for general practitioners (GP). Lactose intolerance (LI) often remains undiagnosed in these patients. Genetic testing for the homozygous -13910CC variant of the MCM-6 gene (LI+) combined with a lactose-restricted diet (LRD) seems to be an acceptable approach. The primary aim of the study was to determine the effect of a LRD in patients with chronic abdominal complaints without a definite diagnosis, with or without the homozygous -13910CC variant. The secondary aim was to determine in family practices the prevalence of undiagnosed LI in these patients.

In 25 practices around Düsseldorf (Germany) all patients presenting with chronic abdominal complaints for at least 12 months without definite diagnosis were identified by their GPs. Patients participating underwent a MCM-6 gene test and all, including those not genetically predisposed, were asked to keep a LRD for eight weeks. Symptoms were evaluated three times over two months using a standardized gastrointestinal Questionnaire (GIQLI, max. score 144).

210 patients were included. The gene test revealed 29.5% genetically positive for the homozygous T-13910-C mutation (LI+). All patients showed a significant increase in GIQLI scores (improvement) during the observation period, i.e. after four and eight weeks on the diet (p = 0.001, two-way repeated measures ANOVA). There was no significant difference between both groups (LI+/LI-) at any point of symptom measurement.

A lactose-restricted diet showed an unspecific positive effect for patients with chronic abdominal pain without a defined diagnosis. For the LI-group, this could be explained by an unspecific effect of a diet in general, e.g., getting special attention. This can be important for a group of patients probably having psychosomatic complaints focussed on the abdomen.