The iceberg cometh: Establishing the prevalence of celiac disease in the United States and Finland

Abstract

Fasano A, Berti I, Gerarduzzi T, Not T, Colletti RB, Drago S, Elitsur Y, Green PHR, Guandalini S, Hill ID, Pietzak M, Ventura A, Thorpe M, Kryszak D, Fornaroli F, Wasserman SS, Murray JA, Horvath K (Center for Celiac Research, University of Maryland School of Medicine). Prevalence of celiac disease in at-risk and not-at-risk groups in the United States: a large multicenter study. Arch Intern Med 2003;163:286–292.Maki M, Mustalahti K, Kokkonen J, Kulmala P, Haapalahti M, Karttunen T, Ilonen J, Laurila K, Dahlbom I, Hansson T, Höpfl P, Knip M (University of Tampere, Tampere, Finland). Prevalence of celiac disease among children in Finland. N Engl J Med 2003;348:2517–2524.Celiac disease (CD) is a T-cell mediated enteropathy provoked by ingested gluten in genetically susceptible individuals. Patients often present with classical symptoms including diarrhea, failure to thrive, and anemia. Well-recognized related phenomena include extraintestinal symptoms (hepatitis, seizures, arthropathy, infertility), long-term complications (lymphoma, osteoporosis, short stature), and associated autoimmune diseases (diabetes, thyroiditis). While CD in Europe is known to occur in as many as 1 in 130 individuals, the diagnosis is still thought to be uncommon in the United States.The debate about the “true” prevalence of disease has been revitalized by the growing reliability of serologic testing and efforts to screen large numbers of people. To address this debate, 2 recent studies examined the prevalence of CD in 2 different populations of children. Fasano et al. (Arch Intern Med 2003;163:286–292) used a multicenter approach to assess disease prevalence in a large cohort of pediatric subjects in the United States with and without specific risk factors for CD. Maki et al. (N Engl J Med 2003;348:2517–2524) performed serum analysis of samples from a well-defined group of school children in Finland to assess the frequency of CD. Both hypothesized that the prevalence of CD is higher in general and in specific at-risk populations than currently recognized. In addition, they attempted to provide evidence supporting the iceberg analogy linked to CD: the existence of both a highly visible group of affected patients with significant symptoms, abnormal serology, and pathological mucosa and a heretofore invisible group with abnormal serology/genetic markers, variably pathological mucosa, and absent/minimal symptoms.In the first study, 13,145 subjects from 32 states were screened for serological evidence of CD between February 1996 and May 2001. Serological analysis was performed using 3 different tests including IgA and IgG anti-gliadin antibodies (AGA, IgA human tissue transglutaminase antibodies [hTTG], and IgA endomysial antibodies [EMA]). EMA-positive subjects were tested for HLA haplotypes associated with CD. Endoscopy with mucosal biopsy was recommended for EMA-positive individuals and for subjects who were IgG AGA positive and IgA deficient. Criteria for diagnosis of CD included either EMA positive serology with positive duodenal biopsy or positive serologies with the appropriate HLA haplotype. Logistic regressional analysis was used to examine relationships among several independent variables versus outcomes of CD testing. Fisher exact tests served to test comparisons between HLA gene frequencies and clinical groupings.Samples were obtained from 9019 subjects “at risk” (defined as first and second-degree relatives of patients with biopsy-proven CD or children or adults with symptoms frequently associated with CD) and from 4126 “not at risk” subjects (defined as blood donors, schoolchildren, and patients seen for routine check ups). Clinical and historical details were abstracted from questionnaires provided to all subjects tested. Age and sex distribution closely approximated United States demographics.Of all subjects screened, 350 (2.7%) were EMA positive. In at-risk groups, CD prevalence (i.e., first-degree relatives, second-degree relatives, and symptomatic adults) was 1:22, 1:39, and 1:68, respectively. Of symptomatic children, 1:25 were EMA positive. All ages of children (1–18 years) demonstrated similar frequencies of positive serologies. Mucosal biopsy specimens were obtained from 33% (116/350) of EMA-positive subjects and although all were abnormal, only 34% of this group revealed classical Marsh 3b or c findings. Of the remaining EMA-positive group without biopsy (234 subjects), 56 went on a gluten-free diet, 55 remained on an unrestricted diet, 52 were undecided, and 71 were denied mucosal biopsy either by their physician or insurance company. All EMA-positive subjects were also hTTG positive and, when tested, all had CD-associated HLA haplotypes.Analysis of symptoms determined that almost half of the 350 EMA-positive subjects were asymptomatic. Diarrhea, abdominal pain, and constipation were the most common presenting symptoms, but most subjects had asymptomatic disease or demonstrated extra-intestinal findings including Down’s syndrome, infertility, Type I diabetes, anemia, short stature, joint pain, arthritis, fatigue, asthma, osteoporosis, and Sjögren syndrome. Logistic regression using genetic-relatedness, age, sex, and presence of symptoms as factors revealed that only genetic-relatedness significantly predicted presence of CD.Prevalence of EMA positivity in not at-risk adult subjects was 1:105 and in children, 1:320. Mucosal biopsies were performed in 30% of these patients and results were abnormal in all. A prevalence of 1:236 was identified in minority groups.The authors state that their findings contradict previously held beliefs that CD is uncommon in the United States. Furthermore, the large number of asymptomatic “silent” CD subjects highlights the importance of screening even in asymptomatic individuals. Finally, results of logistical regression analysis make plain the importance of the hereditary predisposition as the dominant predictor of CD.Acknowledged limitations included lack of random sampling of at-risk subjects, lack of duodenal biopsies in a majority of EMA-positive subjects, lack of 100% sensitivity of the screening test (EMA positivity), and insufficient inclusion of non-white individuals.During 2001, Maki et al. performed hTTG, EMA, and HLA genotype testing on 3654 Finnish schoolchildren. The sera had been collected in 1994 during a previous study assessing for risk factors for Type 1 diabetes mellitus. All children who tested positive, and had not received the diagnosis of CD during the previous 7 years, were asked to undergo esophagogastroduodenoscopy and mucosal biopsy. Diagnostic criteria for CD focused on increased villous-crypt ratio. HLA typing was performed on frozen sections of duodenal tissue.The results of this study revealed 56 of 3654 children had a positive CD titer; 37 were ultimately found to have an abnormal duodenal biopsy for a minimal prevalence of 1:99. Despite the fact that 56 of 3654 subjects showed serological evidence of CD in samples from 1994, CD was not a clinical diagnosis in any of the subjects at that time; thus, 56 subjects had evidence of “silent CD.”Between 1994 and 2001, 10 subjects received the diagnosis of CD on the basis of gastrointestinal symptoms and abnormal duodenal biopsy. Of these, 9 had increased IgA hTTG and EMA and 1 patient with IgA deficiency had increased IgG hTTG and EMA. Of the remaining 46 hTTG/EMA-positive subjects, 36 underwent mucosal biopsy and 27 had diagnostic findings. Of the remaining 9 with normal biopsies, 8 had increased T cells and all had HLA-DR genotyping suggestive of CD. HLA analysis of all 3654 subjects revealed 18.1% and 39.6% of children tested positive for HLA-DR3-DQ2/HLA-DR3-DQ2 or HLA-DR4-DQ8 haplotypes, respectively. Of the htTG/EMA-positive subjects, 96% carried one of these haplotypes. The authors concluded that “silent CD” is highly prevalent in an unselected population of Finnish children and adults.CommentThe results of these 2 important studies emphasize the relevance of genetic predisposition as a predisposing factor for CD and highlight the power of current serological techniques. Importantly, each detected a significant number of asymptomatic patients—those below the tip of the visible iceberg. In the end, these efforts provide additional strong support for larger-scale targeted screening as a part of pediatric care.Although Fasano’s study proposes that genetic relatedness significantly predicts the presence of CD, the specific gene(s) defining this predisposition remain largely unknown. Genetic diseases such as trisomy 21 and Turner’s syndrome are clearly associated with CD. Twin studies (Gut 2002;50:624–628) identify high concordance rates in CD (monozygotic twins 75%, dizygotic twins 11%). In addition, greater than 95% of individuals with CD carry specific MHC II DQ2 genes (DQA1-0501 and DQB1-0201) (N Engl J Med 2002;346:180–188). In contrast, studies of twins (Gut 2002;50:624–628) and family pedigrees suggest that HLA contributes no more than 40% to the overall risk of disease given an affected twin or sibling. Additionally, as shown by Maki et al. here and previously by others, most people who carry the implicated MHC genes never develop CD.Despite these complex genetic relationships, both studies support the use of early testing for CD. Recent data suggests that patients who develop CD in association with autoimmune (AI) diseases as toddlers may be genetically distinct from those with AI diseases that present during adulthood (Gut 2001;49:463–464). Early withdrawal of gluten from those with childhood-onset CD may prevent development of autoimmune (AI) disease, whereas such protection might not be afforded to those with adult-onset disease (Gut 2001;49:502–505).Serological testing can provide health care workers with vital and illuminating information. A dramatic example (Lancet 1999;354:9179) includes a recent study of blood samples from nearly 1000 Bedouin children that revealed 5% of subjects had positive EMA serology. Many of these children were malnourished secondary to what was presumed to be poor calorie intake. Those subjects with biopsy-proven CD who restricted wheat from their diet demonstrated significant clinical improvement. In the present studies, EMA and hTTG tests allowed identification of not only symptomatic individuals but also those with silent disease. In addition, Maki et al. show the strong correlation between EMA and hTTG testing.Although the gold standard for diagnosis of CD remains the small intestinal biopsy with a clinical response to gluten withdrawal, these results suggest the utility of blood sampling as a sole diagnostic test. Of the 350 subjects who were EMA positive in the Fasano et al. study, 116 (33%) underwent endoscopy with biopsy. There were no false-positive serologic tests. As well, no differences were found between the EMA-positive subjects with abnormal HLA patterns who underwent biopsy and those who did not have endoscopy, suggesting serology alone was an adequate diagnostic tool. Likewise, Maki et al. found that 56 of 3654 asymptomatic children and adolescents were found to have abnormal serology suggestive of CD. Given this information, some might ask whether we may soon be withholding biopsy confirmation in select cases of CD?Several important factors favor intestinal biopsy as the “gold standard” diagnostic test for CD. First, these studies were not designed to validate serologic and genetic tests as the sole diagnostic technique. Studies examining this question (J Peds 2000;137:356–360, Pediatrics 2001;107:e8) report positive predictive values of 67%–83% in samples drawn from North American populations. Second, although the results from these studies clearly point to the fact that a significant percentage of patients with abnormal EMA testing had abnormal mucosal biopsy results, we do not know whether the remaining EMA-positive subjects not undergoing endoscopy in fact have CD. Whereas 27 patients had increased crypt villous ratio, 9 patients in the study by Maki et al. were reported to have normal mucosal biopsy results (except for increased T cells). Long-term follow-up of these patients will be instructive as to the meaning of these findings. Last, removal of wheat products from the diet is not an easy task; before committing patients to this lifelong treatment, it is imperative to obtain the most sensitive and specific diagnostic information possible. Thus, the precedent and intuitive importance of histologic confirmation still remains.In summary, these studies emphasize the importance of CD as a diagnostic consideration for a wide array of clinical symptoms, tighten links between CD and genetics, validate extant serologic testing methods, and most importantly, document the high prevalence of CD in 2 different populations. Multicenter collaborative and longitudinal studies such as these serve as excellent examples of the cooperation and patience necessary to answer important epidemiological questions. O jest unseen, inscrutable, invisible, As a nose on a man’s face, or a weathercock on a steeple.—William Shakespeare (1564–1616) The Two Gentleman of Verona Fasano A, Berti I, Gerarduzzi T, Not T, Colletti RB, Drago S, Elitsur Y, Green PHR, Guandalini S, Hill ID, Pietzak M, Ventura A, Thorpe M, Kryszak D, Fornaroli F, Wasserman SS, Murray JA, Horvath K (Center for Celiac Research, University of Maryland School of Medicine). Prevalence of celiac disease in at-risk and not-at-risk groups in the United States: a large multicenter study. Arch Intern Med 2003;163:286–292. Maki M, Mustalahti K, Kokkonen J, Kulmala P, Haapalahti M, Karttunen T, Ilonen J, Laurila K, Dahlbom I, Hansson T, Höpfl P, Knip M (University of Tampere, Tampere, Finland). Prevalence of celiac disease among children in Finland. N Engl J Med 2003;348:2517–2524. Celiac disease (CD) is a T-cell mediated enteropathy provoked by ingested gluten in genetically susceptible individuals. Patients often present with classical symptoms including diarrhea, failure to thrive, and anemia. Well-recognized related phenomena include extraintestinal symptoms (hepatitis, seizures, arthropathy, infertility), long-term complications (lymphoma, osteoporosis, short stature), and associated autoimmune diseases (diabetes, thyroiditis). While CD in Europe is known to occur in as many as 1 in 130 individuals, the diagnosis is still thought to be uncommon in the United States. The debate about the “true” prevalence of disease has been revitalized by the growing reliability of serologic testing and efforts to screen large numbers of people. To address this debate, 2 recent studies examined the prevalence of CD in 2 different populations of children. Fasano et al. (Arch Intern Med 2003;163:286–292) used a multicenter approach to assess disease prevalence in a large cohort of pediatric subjects in the United States with and without specific risk factors for CD. Maki et al. (N Engl J Med 2003;348:2517–2524) performed serum analysis of samples from a well-defined group of school children in Finland to assess the frequency of CD. Both hypothesized that the prevalence of CD is higher in general and in specific at-risk populations than currently recognized. In addition, they attempted to provide evidence supporting the iceberg analogy linked to CD: the existence of both a highly visible group of affected patients with significant symptoms, abnormal serology, and pathological mucosa and a heretofore invisible group with abnormal serology/genetic markers, variably pathological mucosa, and absent/minimal symptoms. In the first study, 13,145 subjects from 32 states were screened for serological evidence of CD between February 1996 and May 2001. Serological analysis was performed using 3 different tests including IgA and IgG anti-gliadin antibodies (AGA, IgA human tissue transglutaminase antibodies [hTTG], and IgA endomysial antibodies [EMA]). EMA-positive subjects were tested for HLA haplotypes associated with CD. Endoscopy with mucosal biopsy was recommended for EMA-positive individuals and for subjects who were IgG AGA positive and IgA deficient. Criteria for diagnosis of CD included either EMA positive serology with positive duodenal biopsy or positive serologies with the appropriate HLA haplotype. Logistic regressional analysis was used to examine relationships among several independent variables versus outcomes of CD testing. Fisher exact tests served to test comparisons between HLA gene frequencies and clinical groupings. Samples were obtained from 9019 subjects “at risk” (defined as first and second-degree relatives of patients with biopsy-proven CD or children or adults with symptoms frequently associated with CD) and from 4126 “not at risk” subjects (defined as blood donors, schoolchildren, and patients seen for routine check ups). Clinical and historical details were abstracted from questionnaires provided to all subjects tested. Age and sex distribution closely approximated United States demographics. Of all subjects screened, 350 (2.7%) were EMA positive. In at-risk groups, CD prevalence (i.e., first-degree relatives, second-degree relatives, and symptomatic adults) was 1:22, 1:39, and 1:68, respectively. Of symptomatic children, 1:25 were EMA positive. All ages of children (1–18 years) demonstrated similar frequencies of positive serologies. Mucosal biopsy specimens were obtained from 33% (116/350) of EMA-positive subjects and although all were abnormal, only 34% of this group revealed classical Marsh 3b or c findings. Of the remaining EMA-positive group without biopsy (234 subjects), 56 went on a gluten-free diet, 55 remained on an unrestricted diet, 52 were undecided, and 71 were denied mucosal biopsy either by their physician or insurance company. All EMA-positive subjects were also hTTG positive and, when tested, all had CD-associated HLA haplotypes. Analysis of symptoms determined that almost half of the 350 EMA-positive subjects were asymptomatic. Diarrhea, abdominal pain, and constipation were the most common presenting symptoms, but most subjects had asymptomatic disease or demonstrated extra-intestinal findings including Down’s syndrome, infertility, Type I diabetes, anemia, short stature, joint pain, arthritis, fatigue, asthma, osteoporosis, and Sjögren syndrome. Logistic regression using genetic-relatedness, age, sex, and presence of symptoms as factors revealed that only genetic-relatedness significantly predicted presence of CD. Prevalence of EMA positivity in not at-risk adult subjects was 1:105 and in children, 1:320. Mucosal biopsies were performed in 30% of these patients and results were abnormal in all. A prevalence of 1:236 was identified in minority groups. The authors state that their findings contradict previously held beliefs that CD is uncommon in the United States. Furthermore, the large number of asymptomatic “silent” CD subjects highlights the importance of screening even in asymptomatic individuals. Finally, results of logistical regression analysis make plain the importance of the hereditary predisposition as the dominant predictor of CD. Acknowledged limitations included lack of random sampling of at-risk subjects, lack of duodenal biopsies in a majority of EMA-positive subjects, lack of 100% sensitivity of the screening test (EMA positivity), and insufficient inclusion of non-white individuals. During 2001, Maki et al. performed hTTG, EMA, and HLA genotype testing on 3654 Finnish schoolchildren. The sera had been collected in 1994 during a previous study assessing for risk factors for Type 1 diabetes mellitus. All children who tested positive, and had not received the diagnosis of CD during the previous 7 years, were asked to undergo esophagogastroduodenoscopy and mucosal biopsy. Diagnostic criteria for CD focused on increased villous-crypt ratio. HLA typing was performed on frozen sections of duodenal tissue. The results of this study revealed 56 of 3654 children had a positive CD titer; 37 were ultimately found to have an abnormal duodenal biopsy for a minimal prevalence of 1:99. Despite the fact that 56 of 3654 subjects showed serological evidence of CD in samples from 1994, CD was not a clinical diagnosis in any of the subjects at that time; thus, 56 subjects had evidence of “silent CD.” Between 1994 and 2001, 10 subjects received the diagnosis of CD on the basis of gastrointestinal symptoms and abnormal duodenal biopsy. Of these, 9 had increased IgA hTTG and EMA and 1 patient with IgA deficiency had increased IgG hTTG and EMA. Of the remaining 46 hTTG/EMA-positive subjects, 36 underwent mucosal biopsy and 27 had diagnostic findings. Of the remaining 9 with normal biopsies, 8 had increased T cells and all had HLA-DR genotyping suggestive of CD. HLA analysis of all 3654 subjects revealed 18.1% and 39.6% of children tested positive for HLA-DR3-DQ2/HLA-DR3-DQ2 or HLA-DR4-DQ8 haplotypes, respectively. Of the htTG/EMA-positive subjects, 96% carried one of these haplotypes. The authors concluded that “silent CD” is highly prevalent in an unselected population of Finnish children and adults. CommentThe results of these 2 important studies emphasize the relevance of genetic predisposition as a predisposing factor for CD and highlight the power of current serological techniques. Importantly, each detected a significant number of asymptomatic patients—those below the tip of the visible iceberg. In the end, these efforts provide additional strong support for larger-scale targeted screening as a part of pediatric care.Although Fasano’s study proposes that genetic relatedness significantly predicts the presence of CD, the specific gene(s) defining this predisposition remain largely unknown. Genetic diseases such as trisomy 21 and Turner’s syndrome are clearly associated with CD. Twin studies (Gut 2002;50:624–628) identify high concordance rates in CD (monozygotic twins 75%, dizygotic twins 11%). In addition, greater than 95% of individuals with CD carry specific MHC II DQ2 genes (DQA1-0501 and DQB1-0201) (N Engl J Med 2002;346:180–188). In contrast, studies of twins (Gut 2002;50:624–628) and family pedigrees suggest that HLA contributes no more than 40% to the overall risk of disease given an affected twin or sibling. Additionally, as shown by Maki et al. here and previously by others, most people who carry the implicated MHC genes never develop CD.Despite these complex genetic relationships, both studies support the use of early testing for CD. Recent data suggests that patients who develop CD in association with autoimmune (AI) diseases as toddlers may be genetically distinct from those with AI diseases that present during adulthood (Gut 2001;49:463–464). Early withdrawal of gluten from those with childhood-onset CD may prevent development of autoimmune (AI) disease, whereas such protection might not be afforded to those with adult-onset disease (Gut 2001;49:502–505).Serological testing can provide health care workers with vital and illuminating information. A dramatic example (Lancet 1999;354:9179) includes a recent study of blood samples from nearly 1000 Bedouin children that revealed 5% of subjects had positive EMA serology. Many of these children were malnourished secondary to what was presumed to be poor calorie intake. Those subjects with biopsy-proven CD who restricted wheat from their diet demonstrated significant clinical improvement. In the present studies, EMA and hTTG tests allowed identification of not only symptomatic individuals but also those with silent disease. In addition, Maki et al. show the strong correlation between EMA and hTTG testing.Although the gold standard for diagnosis of CD remains the small intestinal biopsy with a clinical response to gluten withdrawal, these results suggest the utility of blood sampling as a sole diagnostic test. Of the 350 subjects who were EMA positive in the Fasano et al. study, 116 (33%) underwent endoscopy with biopsy. There were no false-positive serologic tests. As well, no differences were found between the EMA-positive subjects with abnormal HLA patterns who underwent biopsy and those who did not have endoscopy, suggesting serology alone was an adequate diagnostic tool. Likewise, Maki et al. found that 56 of 3654 asymptomatic children and adolescents were found to have abnormal serology suggestive of CD. Given this information, some might ask whether we may soon be withholding biopsy confirmation in select cases of CD?Several important factors favor intestinal biopsy as the “gold standard” diagnostic test for CD. First, these studies were not designed to validate serologic and genetic tests as the sole diagnostic technique. Studies examining this question (J Peds 2000;137:356–360, Pediatrics 2001;107:e8) report positive predictive values of 67%–83% in samples drawn from North American populations. Second, although the results from these studies clearly point to the fact that a significant percentage of patients with abnormal EMA testing had abnormal mucosal biopsy results, we do not know whether the remaining EMA-positive subjects not undergoing endoscopy in fact have CD. Whereas 27 patients had increased crypt villous ratio, 9 patients in the study by Maki et al. were reported to have normal mucosal biopsy results (except for increased T cells). Long-term follow-up of these patients will be instructive as to the meaning of these findings. Last, removal of wheat products from the diet is not an easy task; before committing patients to this lifelong treatment, it is imperative to obtain the most sensitive and specific diagnostic information possible. Thus, the precedent and intuitive importance of histologic confirmation still remains.In summary, these studies emphasize the importance of CD as a diagnostic consideration for a wide array of clinical symptoms, tighten links between CD and genetics, validate extant serologic testing methods, and most importantly, document the high prevalence of CD in 2 different populations. Multicenter collaborative and longitudinal studies such as these serve as excellent examples of the cooperation and patience necessary to answer important epidemiological questions. O jest unseen, inscrutable, invisible, As a nose on a man’s face, or a weathercock on a steeple.—William Shakespeare (1564–1616) The Two Gentleman of Verona The results of these 2 important studies emphasize the relevance of genetic predisposition as a predisposing factor for CD and highlight the power of current serological techniques. Importantly, each detected a significant number of asymptomatic patients—those below the tip of the visible iceberg. In the end, these efforts provide additional strong support for larger-scale targeted screening as a part of pediatric care. Although Fasano’s study proposes that genetic relatedness significantly predicts the presence of CD, the specific gene(s) defining this predisposition remain largely unknown. Genetic diseases such as trisomy 21 and Turner’s syndrome are clearly associated with CD. Twin studies (Gut 2002;50:624–628) identify high concordance rates in CD (monozygotic twins 75%, dizygotic twins 11%). In addition, greater than 95% of individuals with CD carry specific MHC II DQ2 genes (DQA1-0501 and DQB1-0201) (N Engl J Med 2002;346:180–188). In contrast, studies of twins (Gut 2002;50:624–628) and family pedigrees suggest that HLA contributes no more than 40% to the overall risk of disease given an affected twin or sibling. Additionally, as shown by Maki et al. here and previously by others, most people who carry the implicated MHC genes never develop CD. Despite these complex genetic relationships, both studies support the use of early testing for CD. Recent data suggests that patients who develop CD in association with autoimmune (AI) diseases as toddlers may be genetically distinct from those with AI diseases that present during adulthood (Gut 2001;49:463–464). Early withdrawal of gluten from those with childhood-onset CD may prevent development of autoimmune (AI) disease, whereas such protection might not be afforded to those with adult-onset disease (Gut 2001;49:502–505). Serological testing can provide health care workers with vital and illuminating information. A dramatic example (Lancet 1999;354:9179) includes a recent study of blood samples from nearly 1000 Bedouin children that revealed 5% of subjects had positive EMA serology. Many of these children were malnourished secondary to what was presumed to be poor calorie intake. Those subjects with biopsy-proven CD who restricted wheat from their diet demonstrated significant clinical improvement. In the present studies, EMA and hTTG tests allowed identification of not only symptomatic individuals but also those with silent disease. In addition, Maki et al. show the strong correlation between EMA and hTTG testing. Although the gold standard for diagnosis of CD remains the small intestinal biopsy with a clinical response to gluten withdrawal, these results suggest the utility of blood sampling as a sole diagnostic test. Of the 350 subjects who were EMA positive in the Fasano et al. study, 116 (33%) underwent endoscopy with biopsy. There were no false-positive serologic tests. As well, no differences were found between the EMA-positive subjects with abnormal HLA patterns who underwent biopsy and those who did not have endoscopy, suggesting serology alone was an adequate diagnostic tool. Likewise, Maki et al. found that 56 of 3654 asymptomatic children and adolescents were found to have abnormal serology suggestive of CD. Given this information, some might ask whether we may soon be withholding biopsy confirmation in select cases of CD? Several important factors favor intestinal biopsy as the “gold standard” diagnostic test for CD. First, these studies were not designed to validate serologic and genetic tests as the sole diagnostic technique. Studies examining this question (J Peds 2000;137:356–360, Pediatrics 2001;107:e8) report positive predictive values of 67%–83% in samples drawn from North American populations. Second, although the results from these studies clearly point to the fact that a significant percentage of patients with abnormal EMA testing had abnormal mucosal biopsy results, we do not know whether the remaining EMA-positive subjects not undergoing endoscopy in fact have CD. Whereas 27 patients had increased crypt villous ratio, 9 patients in the study by Maki et al. were reported to have normal mucosal biopsy results (except for increased T cells). Long-term follow-up of these patients will be instructive as to the meaning of these findings. Last, removal of wheat products from the diet is not an easy task; before committing patients to this lifelong treatment, it is imperative to obtain the most sensitive and specific diagnostic information possible. Thus, the precedent and intuitive importance of histologic confirmation still remains. In summary, these studies emphasize the importance of CD as a diagnostic consideration for a wide array of clinical symptoms, tighten links between CD and genetics, validate extant serologic testing methods, and most importantly, document the high prevalence of CD in 2 different populations. Multicenter collaborative and longitudinal studies such as these serve as excellent examples of the cooperation and patience necessary to answer important epidemiological questions. O jest unseen, inscrutable, invisible, As a nose on a man’s face, or a weathercock on a steeple. —William Shakespeare (1564–1616) The Two Gentleman of Verona