Down's syndrome (DS) is the most frequent chromosomal anomaly observed
in the general population, affecting 1 in 800 newborns throughout
the world and is the main genetic factor for moderate mental retardation
Different studies have shown that patients with DS present several
immune dysfunctions (),
which lead to increased frequency of recurrent infections, as well
as autoimmune diseases. A high association between DS and autoimmune
diseases has been already reported by several authors (),
with the most significant association with celiac disease (CD) ()
and autoimmune thyroiditis ().
CD affects individuals of all ages and is characterized by permanent
gluten intolerance. In its classic form, CD appears with symptoms
and signs of intestinal malabsorption. However, the disease may
occur in a silent or latent form ().
According to Marsh (),
the duodenal mucosa can be normal or present changes ranging from
mild alterations to severe atrophy in mucosal architecture. The
treatment with a gluten-free diet results in clinical and mucosal
recovery, with recurrence of the disease after the return of gluten
to the diet ().
The classic and symptomatic form of CD is the presence of diarrhea,
vomiting and weight loss, which appears in a minority of cases.
On the other hand, most of the patients present unspecific gastroenterologic
symptoms such as dyspepsia, abdominal pain, flatulence and alteration
of the intestinal rhythm. These characteristics often cause delay
in CD diagnosis and the incorrect management of patients ().
In 1975, Bentley reported for the first time the association between
CD and DS ().
In the following years, several reports showed increased frequency
of CD in individuals with DS in different populations, with a prevalence
ranging from 3.2 to 10.3% ().
In this study we investigate the prevalence of CD in children with
DS from southern Brazil.
Materials and methods
The institutional ethics committee approved the present investigation.
Seventy-one consecutive DS patients (32 female and 39 male) with
mean age 6.12 years (range 2-18 years) from the DS clinic of the
Hospital de Clínicas - Universidade Federal do Paraná
(UFPR) (Curitiba, Brazil) were studied. DS patients older than 18
years were excluded from the study. After formal consenting of DS
children's first-degree relatives, 3 ml of blood were collected
from each subject. Samples were centrifuged and the serum separated,
aliquoted and immediately stored at -80 °C, until used. Only
the EmA-IgA/anti-tTG positive patients were clinically evaluated
and submitted to upper gastrointestinal endoscopy. Crypt hyperplasia
and villous atrophy were classified as partial (PVA) or total (TVA),
according to Marsh ().
Blood samples of 80 healthy children of the same geographic area
of the patients, matched with sex and age with the DS group (38
female and 42 male, mean age 8.02 years), range 2-19 years, were
used as controls.
All subjects were screened for EmA-IgA according to Volta et al.
using immunofluorescence indirect assay, with human umbilical cord
as substrate and FITC anti-IgA human as conjugate (INOVA, USA).
Anti-tissue transglutaminase IgA antibodies (tTG) were determined
by enzyme-linked immunosorbent assay (ELISA) with guinea pig liver
tTG as antigen, using a commercial kit (INOVA Diagnostics Inc.,
San Diego, CA, USA), according to Dieterich et al ().
Results were considered positive when higher than 20 units.
The total serum IgA levels was determined by turbidimetry (Behring,
Data were analyzed with Statistica (Microsoft, USA) software, using
the Fisher exact test.
Serological screening for CD based on EmA and tTG antibodies was
performed in 71 patients with DS and in 80 healthy children.
These results for DS patients and controls are shown in Figure
1. A highly significant positivity of EmA-IgA (p = 0.021) and anti-tTG
(p < 0.001) was observed in the DS patients when compared to
the controls. Five DS patients (7%; 5/71), four male and one female,
were positive for EmA-IgA, with titers varying from 1/5 to 1/80.
Fourteen patients (17.5%; 14/71), seven male and seven female, were
positive for anti-tTG antibodies with values from 21 to 340 U/ml.
Five of these patients were concomitantly positive for EmA-IgA and
the other nine were only positive for anti-tTG antibodies, presenting
borderline values (Table 1). None of the 80 control individuals
was positive for EmA-IgA or anti-tTG.
Figure 1 -
Anti-endomysial (IgA-EmA) and anti-transglutaminase (tTG) antibodies
in Down syndrome patients and controls
Table 1 -
Antiendomisyum and anti-transglutaminase antibodies, symptoms and
histologic aspects in DS patients
Among the five patients concomitantly positive for EmA-IgA and
anti-tTG antibodies, three showed clinical symptoms such as diarrhea,
abdominal pain, anemia and growth failure (Table 1). Four of them
underwent an upper digestive endoscopy followed by duodenal mucosa
biopsy. Histological aspects of duodenal mucosa compatible with
CD were observed in all patients, three of them presented TVA and
one PVA. Only one asymptomatic patient (EmA 1/5, anti tTG = 72 UI)
did not undergo digestive endoscopy and duodenal biopsy. Thus, the
prevalence of confirmed CD among the investigated DS patients was
Neither the DS patients nor the controls presented IgA deficiency.
This is the first report to show the prevalence of CD in children
with DS in Brazil. Our findings confirmed the increased prevalence
of CD among patients with DS reported by several studies in Europe,
North America and Argentina ().
The prevalence of CD in the general population in these countries
ranges from 1:200 to 1:2,000, and among DS patients it presents
a 20-200 fold increase. In Brazil, the prevalence for CD has been
estimated to be 0.14% (1:687) in the central-western region ()
and 0.1% (1:1,000) in the south region ().
Although not all EmA positive patients in our study underwent an
intestinal biopsy, the confirmed CD prevalence in DS patients was
still very high (5.6%; 1:18), in comparison with the general population
of the same geographical area (1:1,000). If we consider CD prevalence
diagnosed by positive EmA, this prevalence would be 7%. The high
association of CD with DS has not yet been clarified, however both,
CD and DS patients present more frequent dysfunction in their immune
system and are more predisposed to autoimmune diseases, such as
thyroid diseases, diabetes mellitus type 1, lupus and arthritis
Besides that, this association may be related to shared common genetic
markers. It has been shown that the DS patients with CD present
the characteristic CD associated with high-risk human leukocyte
antigens (HLA) DR3 and DQ2 alleles ().
In addition, gene disorders caused by chromosomal imbalance may
be related to the enhanced expression of CD in SD patients.
Different studies have shown that the most sensitive and specific
serologic test for the diagnosis of CD is the assessment of EmA
antibodies. During this investigation, five patients were positive
for EmA-IgA (7%) and four of them underwent duodenal biopsy. All
patients who underwent intestinal biopsy showed clinical manifestations
and histological alterations of intestinal mucosa compatible with
CD. The other patient both EmA-IgA and anti tTG positive was asymptomatic
and did not undergo biopsy. It is possible that this patient had
a latent form of CD, which needs to be followed-up. Thus EmA screening
showed high sensitivity and specificity for the diagnosis of CD
in the investigated patients. Our results corroborate the widely
accepted concept that EmA-IgA is a specific screening test for CD.
EmA negative and anti-tTG positive patients, which did not undergo
duodenal biopsy, will now be followed up. Nevertheless, anti-tTG
antibodies have been shown to be positive in other diseases such
as inflammatory bowel disease, chronic liver disease and diabetes
Also, lower specificity of anti-tTG has been related to the use
of guinea pig liver extract as antigen in the ELISA kit. Recently,
the use of human tissue transglutaminase as purified antigen has
been shown to enhance the specificity of this assay ().
In the first 2 years of life, most of the CD patients present classic
symptoms and when associated with DS this diagnosis is almost always
delayed. Certain characteristics of DS children, such as a distended
abdomen and the tendency to consider growth failure as natural consequences
of the DS, can be responsible for the difficulty in diagnosing CD
in these patients. Thus, several authors consider that the CD is
underestimated as the cause of diarrhea, malnutrition or development
deficit in patients with DS ().
The importance of the CD investigation in DS patients has been
showed in recent studies, which recommend serologic tests every
2 years, since negative young individuals may be positive some years
The data reported in the present study emphasize the value of investigating
CD in DS patients, since the correct and early diagnosis will offer
a better quality of life to the patient and his family.