Maria's lactose intolerance is in her DNA.
Maria carries the CC genotype at LCT/MCM6 rs4988235 — the ancestral, non-persistent allele. Her body switched off the lactase enzyme after weaning, so dairy in adulthood produces the classic bloating-cramps-discomfort cascade. Roughly 60–70% of southern Europeans carry this genotype. Maria's report explains what's actually happening, and what to do about it.
One variant carries most of the signal.
Lactose intolerance is unusual in genetics: a single regulatory SNP explains most adult cases worldwide. DeepDNA cross-checks two more variants relevant to Maria's profile.
Lactase: switched off, by design.
All mammals are born making lactase, the enzyme that breaks lactose (milk sugar) into glucose and galactose. In most of the world, the gene switches off after weaning. About 10,000 years ago, a single mutation upstream of the LCT gene started appearing in dairy-herding populations of northern Europe — and that mutation kept the gene on for life.
"Maria has two copies of the ancestral C allele. Her body produces little adult lactase. Undigested lactose ferments in her colon, which is what hydrogen-breath tests measure — and what her symptoms reflect."
The good news: this isn't a disease. It's the global default. The practical workarounds are well-studied and reliable — and her secretor status (FUT2 GG) means her gut microbiome will respond well to bifidobacteria-rich foods.
Three concrete things to do.
- Hard cheeses and yogurt are usually fine. Aging and fermentation strip most of the lactose. Parmesan, aged manchego, Greek yogurt: low risk. Fresh milk, fresh cheese, ice cream: high risk.
- Lactase pills work. Over-the-counter lactase enzyme taken with the first bite of a dairy-containing meal restores roughly the digestion she would have if she were lactase-persistent.
- Watch for hidden lactose. Bakery items, processed meats, "natural flavorings", and many medications use lactose as a filler. Symptom diary >>> elimination diet.
Sources cited in Maria's full report: Enattah et al. Nature Genetics 2002, ClinVar (rs4988235), Storhaug et al. Lancet Gastroenterol 2017.