Lactose intolerance: a non-allergic disorder often managed by allergologists.

Lactose malabsorption is a very common condition characterized by intestinal lactase deficiency. Primary lactose malabsorption is an inherited deficit present in the majority of the world's population, while secondary bypolactasia can be the consequence of an intestinal disease. The presence of malabsorbed lactose in the colonic lumen may cause gastrointestinal symptoms. This condition is known as lactose intolerance. Lactase non-persistence is the ancestral state, whilst two single nucleotide polymorphisms in the lactase gene have been associated with lactase persistence. These are C/T 13910 and G/A 22018 substitutions. Lactase persistence, this Mendelian dominant trait, only became advantageous after the invention of agriculture, when milk from domesticated animals became available for adults to drink. Lactase persistence is then strongly correlated with the diary history of the population. Diagnosis is assessed clinically by elimination of dietary lactose or, better, by non-invasive tests including hydrogen breath test and genetic test. In patients with lactase non-persistence, treatment should be considered exclusively if intolerance symptoms are present. In the absence of guidelines, the common therapeutic approach tends to exclude milk and dairy products from the diet. However, this strategy may have serious nutritional disadvantages. Several studies have been carried out to find alternative approaches, such as exogenous beta-galactosidase, yogurt and probiotics for their bacterial lactase activity, strategies that can prolong contact time between enzyme and substrate delaying gastrointestinal transit time, and chronic lactose ingestion to enhance colonic adaptation.

The genetic legacy of Paleolithic Homo sapiens sapiens in extant Europeans: a Y chromosome perspective.

A genetic perspective of human history in Europe was derived from 22 binary markers of the nonrecombining Y chromosome (NRY). Ten lineages account for >95% of the 1007 European Y chromosomes studied. Geographic distribution and age estimates of alleles are compatible with two Paleolithic and one Neolithic migratory episode that have contributed to the modern European gene pool. A significant correlation between the NRY haplotype data and principal components based on 95 protein markers was observed, indicating the effectiveness of NRY binary polymorphisms in the characterization of human population composition and history.

Human genomic diversity in Europe: a summary of recent research and prospects for the future.

Gene frequencies in Europe are intermediate with respect to those of other continents. A phylogenetic tree reconstructed from 95 gene frequencies tested on 26 European samples shows some deviant populations (Lapps, Sardinians, Greeks, Yugoslavs, Basques, Icelanders and Finns) and other weakly structured populations. This behavior may have a simple interpretation: Europeans have not evolved according to a tree of descent probably because of the major role played by migrations in prehistorical and historical times. The leading component of the European genetic landscape is a gradient that originates in the Middle East and is directed to the northwest. According to the hypothesis by Ammerman and Cavalli-Sforza this gradient was generated by a migration of Neolithic farmers from Anatolia followed by continuous, partial admixture of the expanding farmers with local hunter-gatherers. Other leading components of the gene frequencies in Europe show correlations with possible movements of Uralic-speaking people and pastoral nomads from a region north of the Caucasus and Black Sea, which according to Gimbutas is the area of origin of Indo-European speakers. This analysis is based on classical pre-DNA genetic markers. The prospect of future research using DNA polymorphisms is discussed in the context of the Human Genome Project.

Effect of iodine administration on thyroid function in diabetic patients.

Iodide-induced hypothyroidism has been observed in subjects treated with compounds with mild antithyroid activity. The hypoglycemic agent tolbutamide belongs to the aminoheterocyclic group, a class of compounds with antithyroid effect. Thus it was thought interesting to study the effect of large doses of iodide on thyroid function in diabetics chronically treated with tolbutamide. Basal thyroid function as assessed by clinical examination and iodothyronine and TSH concentrations was normal in all patients. Furthermore, in diabetics treated with tolbutamide, hormone concentrations were not different from those of patients treated with insulin or diet. Serum T4, T3 and TSH did not show any significant variation throughout the investigation period. Our results suggest that thyroid function is not affected by chronic treatment with tolbutamide even when large doses of iodide are administered.

Synthetic maps of human gene frequencies in Europeans.

Multivarate techniques can be used to condense the information for a large number of loci and alleles into one or a few synthetic variables. The geographic distribution of synthetic variables can be plotted by the same technique used in mapping the gene frequency of a single allele. Synthetic maps were constructed for Europe and the Near East, with the use of principal components to condense the information of 38 independent alleles from ten loci. The first principal component summarizes close to 30% of the total information and shows gradients. Maps thus constructed show clines in remarkable agreement with those expected on the basis of the spread of early farming in Europe, thus supporting the hypothesis that this spread was a demic spread rather than a cultural diffusion of farming technology.