Alpha-1 Antitrypsin Deficiency PI*Z and PI*S Gene Frequency Distribution Using on Maps of the World by an Inverse Distance Weighting (IDW) Multivariate Interpolation Method

Hepat Mon. 2012 Oct;12(10 HCC):e7434. doi: 10.5812/hepatmon.7434. Epub 2012 Oct 21.


Background: Currently, there is a remarkable lack of genetic epidemiological studies on alpha 1-antitrypsin (AAT) deficiency in about half of the 193 countries of the World. This fact impedes the establishment of a true prevalence pattern of this deleterious hereditary disorder in extensive regions of human population. 2.

Objectives: The aim of the present study was to generate detailed maps of the frequency distribution of the two most frequent AAT deficiency alleles (i.e., PI*S and PI*Z) in all areas of the World. 3.

Materials and methods: Available data provided by epidemiological studies performed in 94 of 193 countries worldwide was used to develop detailed maps of these two alleles, We employed an informatics mathematical approach, namely: the ArcMap [a component of ESRI's ArcGIS Geographical Information System (GIS), for Microsoft Windows], based on the inverse distance weighting (IDW) multivariate interpolation method, which creates new numerical points from known data, using a simple logarithm based in the distance existing between them 4.

Results: In this method, PI*S and PI*Z frequencies were represented by colored scales, where qualitative colors were converted into quantitative data, providing information on their distribution in all parts of the world. This approach not only confirmed our previous data, but also provided digital images of the remaining regions of all continents. 5.

Conclusions: By using this approach, striking differences were found among regions, and unsuspected significant values of the PI*S and PI*Z alleles frequencies were obtained for several geographic regions where have not been studied yet. In fact, some of these regions might be considered as priority targets for further screening studies on AAT deficiency, in order to identify, and properly manage, individuals at risk for the diverse adverse health effects associated with AAT deficiency.

Keywords: Alpha 1-Antitrypsin; Alpha 1-Antitrypsin Deficiency; Molecular Epidemiology.