Genetics of β-aminoisobutyric acid excretion / Эрүүл мэндийн лаборатори

ABSTRACT

Background@#It was first proposed by Harris that the constant elevated excretion of beta-aminoisobutyric acid (β-AIB) by some healthy individuals, so called high excretors, is determined by an autosomal recessive gene. Several studies of the variability of β-AIB excretion have been conducted, but they failed to show that the distribution of the variation in β-AIB excretion was bimodal. Most of these studies have been carried out on Caucasoid populations which are not suitable material for proving the bimodality since they have a very low proportion of high excretors of β-AIB. A genetically conditioned high excretion of β-AIB has been detected in 2-8% of Caucasoids and in 35-65% of healthy adults of Mongoloid descent.@*Materials and method@#The study of the distribution of the β-AIB concentration involved 319 unrelated subjects (166 adults and 153 children), and the testing of the hypothesis of autosomal recessive inheritance included the data on 15 complete families. The urinary level of β-AIB was determined using a reversed-phase high-performance liquid chromatography (HPLC). @*Results@#The distribution of urinary concentrations of β-AIB of the surveyed show the bimodality with the antimode at 4.5 (=ln 90.02 mmol of β-AIB/mol creatinine) for adults and at 5,5 (=ln 244,69 mmol/mol creat.) for children. The frequency of high-excretors among adults was 0.706 and that among children was 0.716. The testing of the hypothesis of autosomal recessive inheritance of the elevated excretion of β-AIB showed an absence of a significant difference between observed and theoretical numbers.@*Conclusions@#</br> 1. Bimodal distribution of urinary β-AIB concentration was demonstrated in the Mongolian population, with the frequency of high excretors being 0.706 and the gene frequency being 0.84. </br> 2. Results of the family study were consistent with the hypothesis of autosomal recessive inheritance, high excretors being homozygous for the recessive allele.