Lactose intolerance (primary hypolactasia) is predominantly associated in adult caucasians with a single nucleotide polymorphism in intron 13 of the MCM6 gene upstream of the chromosome 2 LCT gene for lactase. It has been postulated the Charles Darwin had this problem. Actually primary hypolactasia rates vary between about 8% in Northern Europeans to 100% in Thais reflecting the strong selective pressures of European farming practices on their population.
Some parents believe that common infant behaviours such as fussiness, crying, or need for attention are caused by lactose intolerance. This is not supported by evidence.
However the rare congenital lactase deficiency in infants is a serious condition leading to failure to thrive due to the predictable severe diarrhoea, even when breast-fed.
- ↑ Campbell AK, Waud JP, Matthews SB. The molecular basis of lactose intolerance. Science progress. 2009; 92(Pt 3-4):241-87.
- ↑ Sherman AL, Anderson J, Rudolph CD, Walker LS. Lactose-Free Milk or Soy-Based Formulas Do Not Improve Caregivers' Distress or Perceptions of Difficult Infant Behavior. Journal of pediatric gastroenterology and nutrition. 2015 Jul; 61(1):119-24.(Link to article – subscription may be required.)