, Ece Eker 2
, Fulya Çetinkaya 3
, Yonca Eğin 2
, Şengül Aydın 2
, Göksel Vatansever 3
, Ayşe Gül Güven 4
, Zehra Aycan 5
2Department of Pediatric Genetics, Ankara University Faculty of Medicine, Ankara, Türkiye
3Department of Pediatrics, Ankara University Faculty of Medicine, Ankara, Türkiye
4Department of Adolescent Health, Ankara University, Ankara, Türkiye
5Department of Adolescent Health, Ankara University Faculty of Medicine, Ankara, Türkiye; Department of Pediatric Endocrinology, Ankara University Faculty of Medicine, Ankara, Türkiye
Abstract
Objective: Lactose intolerance (LI) is a common cause of gastrointestinal complaints in adolescents and young adults, often leading to unnecessary dietary restrictions and reduced calcium intake. Although lactase non-persistence (LNP) is genetically determined, its clinical expression varies considerably. Genetic variants associated with lactase persistence/non-persistence (LCT/MCM6 locus), particularly rs4988235 and rs3754686, are frequently used in genetic testing; however, their clinical utility remains uncertain, especially in populations with a high prevalence of LNP, such as Türkiye.
Materials and Methods: In this cross-sectional study, 209 individuals aged 12–25 years were evaluated. Lactose-related symptoms were assessed using a validated questionnaire (a score ≥7 defined symptomatic individuals). Consumption of raw milk and fermented dairy products was recorded using a standardized frequency scale. Genotyping of rs4988235 and rs3754686 was performed using TaqMan real-time PCR. Associations between genotype, symptom status, age at symptom onset, and dietary patterns were statistically analyzed.
Results: Among the participants, 116 (55.5%) were symptomatic and 93 (44.5%) were asymptomatic. Symptomatic individuals were significantly older (p<0.001). The genotype distributions of rs4988235 and rs3754686 did not differ between symptomatic and asymptomatic individuals and were not associated with age at symptom onset. Dairy consumption patterns were not associated with symptom severity, although fermented dairy consumption was slightly higher among symptomatic individuals (p=0.046).
Conclusion: Common LCT/MCM6 variants did not predict clinical LI in this adolescent and young adult population. Therefore, routine genetic testing appears unlikely to provide limited additional value in supporting the diagnosis of lactose intolerance, particularly in populations with a high prevalence of LNP. Symptom-based assessment and functional testing should remain central to diagnosis and management, and, supporting appropriate nutritional guidance and avoiding unnecessary dietary restriction.