In the largest study of its kind, researchers studied 47 twin pairs, who were selected on the basis that one belonged to the Italian Celiac Disease Association (AIC).
They were tested for antibodies specific to celiac disease to ensure that "silent" disease was detected, and their genetic profile was mapped.
Tissue samples were taken to confirm changes indicative of the disease.
The findings of the study were reported in the May issue of Gut.
There were 20 (monozygotic) identical twin pairs, 6 of whom were male and 14 of whom were female. There were 27 non-identical (dizygotic) pairs, 8 of whom were male, 7 of whom were female, and 12 of whom were opposite sex pairs.
Some 15 of the identical and 3 of the non-identical twins had signs of celiac disease.
All identical twin pairs had genes that predispose to developing the disease (DQ2 or DQ8, or DRB4).
Five non-identical pairs carried a "risky" gene, but only 1 of the 5 pairs matched.
| A "risky" gene pattern tripled the risk of celiac disease in the co-twin.
The team found that 13 non-identical pairs had different genetic patterns that also increased the risk of developing celiac disease. However, this matched in only 2 pairs.
Being female increased the risk of developing the disease by 30% in a twin who was not affected.
In addition, those over the age of 30 were twice as likely to develop the disease.
A "risky" gene pattern tripled the risk in the co-twin.
The authors conclude that, apart from gluten in the diet, a shared environment has little or no impact on the risk of developing celiac disease in non-identical twins, and that environmental factors have little influence, overall.
However, they suggest that more than one gene may be involved in the development of the disease.
Rather than it being a case of a missing or faulty gene, it is perhaps a series of genetic factors that combine together to produce gluten intolerance.