Screening for coeliac disease: the meaning of low titers of anti-gliadin antibodies (AGA) in non-coeliac children.

Coeliac disease is diagnosed by means of jejunal biopsy, an invasive procedure. Anti-gliadin antibodies (AGA) have therefore been used in the first screening of the disease. On the other hand, low titers of AGA are widely detected also in normal subjects. In order to investigate if low levels of AGA could be correlated with laboratory and clinical data, we performed a study on 167 subjects with various illnesses, such as recurrent abdominal pain, failure to thrive, short stature, diarrhoea or constipation, cow-milk protein intolerance and/or food allergy, recurrent vomiting or previous gastroenteritis, all non coeliac conditions which have been associated with AGA presence. Seventy coeliac children, all biopsied, were selected as a control group. Among the 167 cases we found 60 subjects positive for AGA (35.9%), a high proportion as compared with the general population. Only 33/167 patients, all IgG and IgA AGA positive, fulfil our laboratory and clinical criteria to perform a 'confirming' biopsy. For the 134 residual cases (14 IgA, 13 only IgG AGA positive, 107 AGA negative) a diagnosis of coeliac disease has been excluded by clinical criteria (scoring). As a whole, the patients with coeliac disease had significantly higher levels of AGA of both IgG and IgA classes (p < 0.01). On the other hand, no significant difference emerged for all the anamnestic and laboratory parameters considered between AGA+ and AGA- non-coeliac subjects. However, laboratory parameters of IgG-AGA and/or IgA-AGA positive patients were similar to those of coeliac children for ion, Xylose, total IgA count. As no biopsied case showed mucosal atrophy, it is suggested that the presence of even low AGA levels in non-coeliac children may represent a highly sensitive index of intestinal alteration causing an increased permeability to macromolecules, but it is very unlikely that one could detect coeliac children by means of Ig-AGA among such illnesses and normal subjects. Strong clinical diagnosis and laboratory parameters are required to justify intestinal biopsies. In fact, the production of AGA seems to be a merely immunological phenomenon linked to an increased and probably transient permeability to macromolecules of the intestinal mucosa.

Frequency and clinical pattern of celiac disease among siblings of celiac children.

To investigate the prevalence and clinical and genetic patterns of celiac disease (CD) among siblings of CD patients, 103 siblings and one twin of 80 celiac children were evaluated by means of their clinical history, physical examination, blood indices of nutritional status, and antigliadin antibodies (AGA). Antiendomysium antibody (AEA) levels were determined in 70 patients and 85 subjects were human leucocyte antigen (HLA) typed. On the basis of clinical or laboratory data or both, 21 siblings (20.2%) were submitted to intestinal biopsy, whereas intestinal biopsy in six siblings with positive serologic screening (AGA IgA or AEA or both) was not performed because of parental refusal. In a high percentage of cases (18%), all on a gluten-containing diet, the intestinal mucosa was atrophic, and CD was subsequently diagnosed. Because we could not submit all the siblings to intestinal biopsy, this figure could underestimate the real prevalence of the disease in our series; consequently, it was not possible to calculate accurately the sensitivity and specificity of AGA and AEA. Nevertheless, AEA (positive in all the nine siblings with mucosal atrophy), followed by AGA IgA, proved to be the best screening for CD. Eighteen of 19 CD siblings showed HLA-predisposing antigens. Among the 19 CD siblings, one showed a typical form with gastrointestinal symptoms, two had short stature, one suffered from recurrent vomiting, and in 15, the disease was clinically silent. On the contrary, among siblings who were first diagnosed (index cases), the majority (73.7%) had a typical form of CD, and no clinically silent cases were observed. We did not find any difference between index cases and CD siblings in food habits and distribution of HLA antigens. In 15 of 18 cases, the sibling diagnosed subsequently was the older one. Finally, the typical form of CD was significantly more frequent among the younger brother than the older. In conclusion, the high prevalence of the silent form of CD in our cases indicates that siblings of CD subjects should always be screened for CD. The combination of AGA IgA and AEA represent a good screening method to use in selecting children for the intestinal biopsy.

Use of a threshold serum level of anti-gliadin antibodies improves diagnostic efficiency of the test in adult coeliac disease but is unreliable as a screening test.

Measurement of anti-gliadin antibodies is considered a highly sensitive test for coeliac disease in children. Specificity, however, appears to vary due to the presence of anti-gliadin antibodies in other diseases. Sensitivity and specificity of anti-gliadin antibody measurement for coeliac disease in adults has, thus, been assessed using the ratio of the densitometric unit test/the mean +3SD of densitometric unit values of a pool of sera of healthy biopsy-proven controls. Anti-gliadin antibodies-A and G were measured separately with an enzyme-linked immunosorbent assay in 64 coeliacs (20 males; 44 females; age range 14-71 years) with diagnosis confirmed at jejunal biopsy; and in 60 controls (25 males; 35 females; age range 16-69 years) with normal jejunal biopsy. Detection of anti-gliadin antibodies-A and G had a sensitivity of 58% and 61%, respectively, and a specificity of 85% and 94%. For the procedure a Receiver Operating Characteristic analysis was used. Considering anti-gliadin antibodies-A and G values of at least 0.9 densitometric unit, sensitivity was 50% and 60%, respectively, whereas specificity was 100% for both. These findings confirm the low sensitivity of these measurements in adult coeliacs and thus the unreliability for screening. The high specificity, when using a threshold value of 0.9 densitometric unit, may be useful in the evaluation of adults with suspected coeliac disease.

Coeliac disease, enamel defects and HLA typing.

The presence of dental enamel defects in coeliac disease and their relation to hypocalcaemia or a particular HLA class in 82 Italian children with coeliac disease was studied. Demarcated opacities or hypoplasia were detected in 23 subjects (group 1) while minimal or no dental lesions were found in the remaining 59 patients (group 2); in 189 normal controls, enamel lesions were significantly less frequent than in patients with coeliac disease (14.8% versus 28.0%; p < 0.005). No statistically significant differences were found for age at diagnosis and calcium concentrations between groups 1 and 2. Regression analysis showed a correlation between age at diagnosis and number of teeth with enamel defects. In our patients, the presence of HLA DR3 antigen significantly increased the risk of dental lesions, while genotype DR5,7 seemed to protect against enamel defects. A logistic regression analysis of the variables age, serum calcium concentrations, number of affected teeth, type of enamel defect and DR antigens showed that only DR antigens discriminated coeliac disease patients with from those without enamel defects.

[Antiendomysial antibodies: current role in the diagnosis of celiac disease compared to antigliadin antibodies]. / Anticorpi antiendomisio: ruolo attuale nella diagnosi di malattia celiaca a confronto con gli anticorpi anti-gliadina.

We evaluated in parallel the action of antigliadin (AGA-IgA) and anti-endomysium (EmA) antibodies in a group of 144 coeliac patients during the various diagnostic procedures, and in 277 controls (206 affected by other gastroenterological diseases and 71 healthy or affected by non-gastroenterological diseases, not causing any immune changes). Little difference was observed between the two tests both during the initial phase of the disease and during gluten-free diet. No EmA positivity was observed in controls; AGA-IgA resulted positive in 6.3% of gastroenterological controls and in 5.6% of non-gastroenterological controls. Finally, the sensitivity, specificity and predictability of the two tests were evaluated in a sample of 92 subjects undergoing intestinal biopsy. The results show that the tests have the same sensitivity, but only for EmA 100% specificity was found.

Diabetes-related autoantibodies do appear in children with coeliac disease.

Humoral immune factors related to type 1 diabetes have been investigated in children with coeliac disease. Anti-insulin (IAAb), immunoglobulin (alpha IgAb), islet cell (ICA) and glucagon autoantibodies were examined in 15 children with coeliac disease at diagnosis (group 1), in 15 children with coeliac disease following a gluten-free diet (group 2) and in 30 control patients (groups 3 and 4). IAAb were present in 27% of group 1 and in 20% of group 2 patients and alpha IgAb were significantly increased in group 1 and 2 patients; two patients in group 2 were positive for ICA; none of the coeliac disease patients were positive for anti-glucagon antibodies. The levels of anti-gliadin antibodies in group 1 were positively correlated with those of alpha IgAb. Coeliac disease-related HLA antigens were not correlated with antibody presence. The presence of diabetes-related humoral immune factors in coeliac disease raises the question as to whether or not they are predictive of subclinical pancreatic damage or whether they are simply indicators of a more general autoimmune diathesis.

A study of Italian pediatric celiac disease patients confirms that the primary HLA association is to the DQ(alpha 1*0501, beta 1*0201) heterodimer.

Celiac disease (CD) has been recently reported to be primarily associated with the DQ(alpha 1*0501, beta 1*0201) heterodimer encoded in cis on DR3 haplotype and in trans in DR5,7 heterozygous individuals. The high incidence of DR5,7 heterozygotes, reflecting the high frequency of the DR5 allele in Italy, makes the analysis of the Italian CD patients critical. Polymerase chain reaction-amplified DNA from 50 CD patients and 50 controls, serologically typed for DR and DQw antigens, was hybridized with five DQA1-specific oligonucleotide probes detecting DQA1*0101 + 0102 + 0103, DQA1*0201, DQA1*0301 + 0302, DQA1*0401 + 0501 + 0601, and DQA1*0501 and a DQB1-sequence-specific oligonucleotide probe recognizing DQB1*0201 allele. As expected by the DR-DQ disequilibria, DQA1*0201 [62% in patients versus 26% in controls, relative risk (RR) = 5] and DQA1*0501 (96% versus 56%, RR = 19) show positive association with the disease. Of CD patients, 92% (50% DR3 and 42% DR5,7) compared to 18% of the controls carry both DQA1*0501 and DQB1*0201 alleles, so that the combination confers an RR of 52, higher than both the risks of the single alleles (DQA1*0501 RR = 19, DQB1*0201 RR = 30), confirming the primary role of the dimer in determining genetic predisposition to CD both in DR3 and in DR5,7 subjects.

Short stature as the primary manifestation of monosymptomatic celiac disease.

It is generally accepted that celiac disease (CD) must always be taken into consideration when dealing with children manifesting growth failure. It is therefore important to have laboratory tests capable of detecting patients who should undergo intestinal biopsy. Auxological and endocrine parameters, bone age, some nutritional indices (hemoglobin, serum iron, calcium, total protein, and albumin), and anti-gliadin antibodies (AGA) IgA and IgG and 1-h blood xylose levels were evaluated in 49 children of short stature. On the basis of the intestinal biopsy, 29 (59.1%) patients affected by CD were found. When patients with atrophic and normal intestinal mucosa were compared, significant differences in the frequency of pathological values of hemoglobinemia, serum iron, AGA, and 1-h blood xylose levels were found, whereas no difference was observed in the levels of serum calcium, total protein, and albumin. Bone age was delayed in 81% of the celiac patients and in 47% of the controls. In particular, AGAs were found in 27 of 29 celiac patients and in three control subjects who showed a low level of one of the two antibodies. The results of our study demonstrate that AGA (IgA and IgG), together with 1-h blood xylose, hemoglobinemia, serum iron, and family history of CD determination, are extremely useful for screening patients of short stature. This type of screening cannot, however, replace the intestinal biopsy because such tests cannot be completely sensitive and specific.

Scanning electron microscopy of the small intestine during gluten-challenge in celiac disease.

The celiac disease syndrome is characterized by structural and ultrastructural alterations of the small intestine mucosa. According to criteria by European Society of Paediatric Gastroenterology and Nutrition, the conclusive diagnosis of celiac disease in children depends on the demonstration of histological relapse of the mucosa after reintroduction of gluten in the diet, as this syndrome is a permanent condition of gluten intolerance. Under these diseased conditions, the structure of the intestinal villi has been studied by light microscopy; morphological alterations were revealed only when the gluten challenge induced a clinical relapse. Scanning electron microscopy analyses of the intestinal mucosa in celiac diseased patients showed a strikingly uniform destruction of the villi with changes in their dimensions and arrangement. At high magnification the enterocytes were irregular in size and shape with a decrease and disruption of the glycocalyx. Reductions in length and density of microvilli were also clearly identified. Although these scanning electron microscopy findings could not demonstrate a relationship between the degrees of mucosal atrophy and the duration of the gluten challenge, they nevertheless revealed early stages of fine villous alterations that cannot be detected by the presently employed low resolution light microscopic techniques.

Oligotyping of celiac multiplex families with the 11th International Histocompatibility Workshop reagents.

Using PCR and SSO probes from the 11th International Histocompatibility Workshop, we oligotyped for HLA-DRB1 gene and DQA1*0501, DQB1*0201 alleles 10 celiac families each with 2 affected children. All families belong to the Italian population except for one, whose mother is originally from Cape Verde island. 8/10 sibling pairs share the DQA1*0501/B1*0201 heterodimer, inherited in cis or in trans arrangement. All the dimer-negative patients were DR4-positive.

HLA antigens and antigliadin antibodies in coeliac disease.

Thirty-six coeliac children on gluten-containing diet were studied for AGA IgA and IgG levels. Patients were typed for HLA-A, -B, -C, -DR, -DQ antigens and data were analysed for any correlation between HLA-DR phenotype and AGA levels. AGA IgA and/or IgG were present in all these children. Subjects negative for DR3 or DR7 showed lower AGA levels than those DR3 + and/or DR7 positive. The data suggest that these patients could escape diagnosis if screening for those requiring intestinal biopsy is based only on AGA assay. The observation that coeliac children negative for DR3 and DR7 showed lower AGA levels is consistent with clinical and genetic heterogeneity of coeliac disease.

Beta 2-microglobulin levels in celiac disease.

The serum levels of beta 2-microglobulins (beta 2-m) were studied in 65 celiac children. Significant statistical differences (p less than 0.05) were found between the values of patients on a gluten-containing diet (mean +/- SD, 1.92 +/- 0.64 mg/L) and those on a gluten-free diet for less than (mean +/- SD, 2.38 +/- 0.76 mg/L) or greater than (mean +/- SD, 1.46 +/- 0.77 mg/L) 8 months. A significant difference was also found between the first group and the 15-subject control group, who underwent intestinal biopsy for low stature or chronic diarrhea but had normal intestinal mucosa (mean +/- SD, 1.56 +/- 0.42 mg/L). Serum beta 2-m levels were above normal values (less than 2 mg/L) in 10 of 26 (38.5%) celiac patients on a gluten-containing diet and in two of 15 (13.3%) subjects of the control group. The beta 2-m values of patients on a gluten-free diet for less than or equal to 8 months were significantly different (p less than 0.001) from those of patients on a gluten-free diet for greater than 8 months, as well from those of the control group. No significant differences were found between patients on a gluten-free diet for greater than 8 months and the control group. A significant correlation between the antigliadin antibody (AGA) IgA and beta 2-m in the patients on a gluten-free diet for greater than 8 months and control-group patients was found.(ABSTRACT TRUNCATED AT 250 WORDS)

[Intestinal polyposis in children. Description and differential diagnosis of 2 cases]. / Poliposi intestinale in età pediatrica. Descrizione e diagnosi differenziale di due casi.

The case of a 21-month-old girl with lymphoid nodular hyperplasia and the case of a 9-year-old girl with familial adenomatous polyposis are described. Both patients presented rectal bleeding. A defect of secretory IgA was found in the first patient. In both cases diagnosis was based on medical history, barium enema with aircontrast technique, colonscopy, and endoscopic biopsy. Differential diagnosis and diagnostic procedures in these two diseases are discussed.