Celiac disease is "an inflammatory condition of the small intestine precipitated by the ingestion of wheat in individuals with certain genetic makeups"
From this definition of the disease, we already can see what the two major factors in celiac disease occurrence are: environmental factors (ingestion of wheat, which has gluten) and the genetic factor (a certain genetic predisposition for the disease).
The intolerance to glutton manifests itself in symptoms such as diarrhea, "blistering, burning, itchy rash on the extensor surfaces of the body (dermatitis herpetiformis)"
, bone weakness or tetany.
We have agreed that genetics definitely represent one of the causing factors of celiac disease. According to our primary article, investigation in this sense was performed both on twins and on family relatives. As such, "the concordance rate for celiac disease in monozygotic twins is estimated to be 75%"
, which makes us believe that, at least statistically speaking, genetics plays a large part in the development of celiac disease.
In terms of relatives, "15% of children with celiac disease have a first-degree relative with symptomatic celiac disease"
. Another study, published by Alessio Fasano
, shows the following prevalence of the disease, according to the familial groups: first degree relatives 1 in 22 (1 in 22 out of people having a first degree relative with celiac disease are likely to get the disease as well), second degree relatives 1 in 39, third degree relatives 1 in 56 and overall prevalence (no relatives with celiac disease) 1 in 33.
As such, from these statistical data we notice an increasing probability of having the disease if close relatives have it as well. If we consider the results I have already mentioned, direct observation and statistical records prove that genetic factors contribute to the development of celiac disease.
Biologically speaking, research has isolated only one genetic factor that actually has a role in the development of celiac disease: the HLA-DQ. This is "encoded by the MHC genes DQA1 and DQB on chromosome 6"
. The combination of DQA1*0501 and HLA-DQB1*02 alleles appears in 90% of all persons having the celiac disease.
Our main article however points out that the HLA association does not seem to be enough to prove a genetic occurrence for the disease. This is mainly because, practically only a small proportion of those carrying HLA-DQ2/8 do develop in time the celiac disease. The HLA-DQ2/8 genotype "accounts for approximately a four-to fivefold increased risk"
The HLA region comes as our first genetic determinant, but we should assume that there may be other determinants, many of them even stronger that may increase the probability of contracting the disease. Some scientists believe that the genes in the T cell immune response may have something to do with the celiac disease. The CTLA4 gene in particular has been suspected, even if several results have excluded it as a major risk factor.
The problem with the celiac disease, from a genetic point-of-view, may be the fact that there isn't yet a genetic model for the disease and it is hard to determine a specific gene that may influence disease occurrence. One does yet have to establish the genetic pattern of disease transmittal among relatives, just as much as the "disease gene frequency."
Statistically speaking, besides the figures I have already presented, the number of families that were actually studied remained quite small and, in any case, small enough to crate an impediment in drawing strict genetic conclusions on the disease's causality. Additionally, as the article mentions, there have been differences in diagnostic criteria, which, in turn, will probably lead to different diagnostic subtypes.
From a genetic point-of-view, we may conclude, as such, that, while some statistical data and several scientific genetic conclusions have led us to believe that there is a causal link between the existence of the disease among family members and the occurrence of the disease in a person, the results are not conclusive enough to strongly assert that the celiac disease has definite genetic consequences.
The second factor for disease occurrence we should mention is the environment. This is quite simple, giving the definition of the celiac disease I have already laid out in the beginning of my review. As the celiac disease is characterized by…