No abstract

In Sardinians, adult-type hypolactasia becomes phenotypically evident in all individuals older than 9 years, suggesting that this should be considered the minimum age at which the genetic test for lactase nonpersistence should be applied.

New guidelines for celiac disease (CD) diagnosis from the European Society for Paediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) propose the option to omit the duodenal biopsy in the diagnosis of CD. For this option, all four of the following criteria have to apply in children and adolescents: signs and symptoms suggestive of CD, anti-transglutaminase type 2 antibody (anti-TG2) levels more than 10 times the upper limit of normal, positive confirmation tests of anti-endomysium-IgA antibodies (EMA), and at-risk HLA-DQ2 or HLA-DQ8. Here, we report the case of a female patient, 2 years old, with chronic diarrhea that started after an acute viral gastroenteritis. The patient had anti-TG2 levels of more than 10 times the upper limit of normal, positivity for EMA, antigliadin IgA, and IgG (AGA-IgA, AGA-IgG, respectively), and the at-risk HLA-DRB1*0301, DQB1*0201/DRB1*10, DQB1*0501 genotype, thus fulfilling all criteria for the diagnosis of CD. Although the diarrhea disappeared after about 5 weeks, anti-TG2, EMA, and AGA-IgG remained positive. Therefore, a duodenal biopsy was performed and evidenced a normal mucosa (Marsh 0). After about 18 months, the antibody titer for AGA-IgG, anti-TG2, and EMA became negative. The patient was all the time on a normal, gluten-containing diet. This clinical case represents an exception to the new ESPGHAN guidelines for CD diagnosis. During 5 weeks, the new ESPGHAN criteria were all fulfilled, allowing to propose for this patient the diagnosis of CD without performing a duodenal biopsy. Therefore, a prudent approach is suggested when the pediatric gastroenterologist makes a diagnosis of CD without duodenal biopsy.

Although Sardinia does not show reduced diversity at the TPMT locus, the spectrum of TPMT allele frequencies affords evidence of remarkable influence of genetic drift and founder effects throughout its population history. In the broad context of the European TPMT diversity, the Sardinians come out as outliers, an observation consistent with previous genetic inferences that Sardinia has features of a genetic isolate.

Adult-type hypolactasia results from the progressive decline of lactase-phlorizin hydrolase activity in enterocytes after weaning. Lactase nonpersistence may determine a primary lactose intolerance with reduced diary product consumption, which is possibly related to an increased risk of colon cancer. Recently, a genetic variant C/T(-13910) upstream of the lactase-phlorizin hydrolase (LCT) gene has been strongly correlated with the lactase persistence/nonpersistence trait in both family and case-control studies. The authors validate a denaturing high-performance liquid chromatography (dHPLC)-based assay versus conventional genotype sequencing in detecting the C/T(-13910) polymorphism of LCT and evaluate its prevalence in 2 different Italian geographical areas and in colorectal cancer patients. DNA samples of 157 healthy subjects and 124 colon cancer patients from Apulia and of 97 healthy subjects from Sardinia were evaluated for the C/T(-13910) polymorphism by dHPLC, sequencing, and restriction fragment length polymorphism (RFLP). Under optimized conditions, dHPLC was as sensitive as DNA sequencing and detected a new genetic variant (T/C(-13913)) in 2 individuals that was not identified by RFLP assay. Frequency of lactase nonpersistence genotype (C/C(-13910)) was similar in healthy subjects from 2 different Italian geographical areas and not increased in patients with colorectal cancer. The results indicate that the dHPLC method may be used as a rapid, noninvasive, and labor-saving screening tool for genotyping C/T(-13910) polymorphism, with high success, low cost, and reproducibility.