Broad-spectrum autism, referred to as pervasive developmental disorder (PDD), may be associated with genetic factors. We examined 241 siblings in 269 Japanese families with affected children. The sibling incidence of PDD was 10.0% whereas the prevalence of PDD in the general population in the same geographic region was 2.1%. Both of these rates are higher than those reported previously, probably because of the expanded clinical criteria applied. The prevalence in males of the general population was 3.3% and that in females was 0.82%. The sibling incidences were 7.7 and 20.0% for families in which the probands were male and female, respectively. Because the reversed sex ratios correspond to the general rule for a multifactorial threshold model, we suggest that most PDD cases result from the cumulative effects of multiple factors (mostly genetic). The sibling incidences were 0 and 10.9% for families in which the proband had low and normal birth-weight, respectively, suggesting the risk is lower in families with lowbirth-weight probands.

An investigation of genetic structures underlying autistic traits was performed with samples from twins for which at least one proband had been ascertained as having autism spectrum disorders (ASDs) in our catchment area. In order to adjust for recent concepts of autism, we employed criteria for the broad spectrum of disease and the childhood autism rating scale (CARS) for quantitative assessment. The CARS test was performed on 45 twin pairs (19 monozygotic, 26 dizygotic) detected with a regional routine screening system. The obtained CARS scores were subjected to structural equation modeling (SEM), incorporating sex differences for each causal influence ascertainment correction, using the Mx software. A best fitting model of causal influences on autistic traits measured continuously, incorporating additive genetic (A) and non-shared environmental influences (E), was generated. With this AE model, the estimated heritability was 0.73 for males and 0.87 for females, based on the continuous CARS scores. There was no evidence for the existence of sex-specific genetic influences. Autistic traits were highly heritable in twins with even broad spectrum of autism, corresponding to the results of early studies based on classical autism. Additive genetic factors were more influential in females than males.

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Adenosine is a physiologically active molecule produced locally in many sites of the body to regulate various cell functions. Measurement of levels of the factor in organs and biological fluids provides clues to its role and we reported an accurate quantitative high-performance liquid chromatography method for urinary adenosine requiring no preliminary sample preparation, other than filtration. Analyses were performed isocratically with a reversed-phase and a molecular exclusion columns connected by a column switch. Each sample was analyzed automatically in 35 min. Linearity could be verified up to 1,000 μ mol/L (r = 0.999) and recovery of adenosine was 94.6 -98.0%. The coefficients of variation (CV) were established to be 0.56 -1.32%, intra-assay, and 1.61 -4.67%, inter-assay. Based on analyses of healthy individuals at different ages, we are here able to provide age-related values, infants (1.51 ± 0.71 μ mol/mmol creatinine) and children (1.06 ± 0.36 and 0.83 ± 0.27 μ mol/mmol creatinine; aged 1 -5 and 6 -10 years), excreting significantly higher amounts of adenosine than adults (0.44 ± 0.08 μ mol/mmol creatinine). We also measured urinary adenosine from patients suffering from metabolic disease or severe respiratory failure and found that unfavorable pathophysiologic conditions are associated with appreciable elevation of adenosine.adenosine; urine; HPLC; column-switching; metabolic disease

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