Objective: To establish a suitable human model for the study of the genetics of complex diseases. Methods: We have selected an Omani Arab population to provide the statistical power required to study the genetics of complex diseases with confidence. This model consists of five multigenerational highly inbred pedigrees, descending from a small number of founders just a few generations ago with environmental homogeneity, restricted geographical distribution, detailed records and well-ascertained and -validated pedigrees. Stringent criteria were adopted for defining the phenotypes of hypertension, diabetes mellitus, dyslipidemias and obesity. The SOLAR genetic software package was used to draw the pedigree structure. Results: Outstanding statistical power to detect susceptibility loci was obtained. Conclusions: This model represents a large homogeneous human family-based population for the study of genetic and environmental factors contributing to complex diseases.

The disease‐like leaf mutant exhibits sensitive symptoms in the absence of pathogens and is an important experimental material for studying leaf development and pathogen resistance mechanisms in plants. We used 60Co γ ray irradiation treatment of a Japanese soybean [Glycine max (L.) Merr.] plant introduction Tamahomore to obtain a new disease‐like mutant, designated NT301. The mutant leaves were significantly smaller and thicker than those of the wild‐type plant, with a reduction in leaf vein growth and increased growth of leaf mesophyll tissue. The surface of these rugose leaves resembled the symptoms of virus infection. Genetic analysis of two crosses between NT301 and the normal parents indicated that the rugose traits were controlled by two pairs of recessive duplicated genes, tentatively designated rl1 and rl2. We mapped rl1 between simple sequence repeats (SSR) markers BARCSOYSSR_18_0415 and BARCSOYSSR_18_0485 on chromosome 18. We mapped rl2 between BARCSOYSSR 08_1700 and Satt409 on chromosome 8, a region that is homoeologous to the rl1 position. We have inferred the possible process for creation of this induced mutant with double recessive genes. Our study will facilitate the gene cloning of rl1 and rl2, providing a new genetic stock for exploring the genetic mechanisms of leaf development and genome evolution in soybean.

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Screening of 9904 Omani schoolchildren from different regions in Oman gave a prevalence rate of rheumatic heart disease of 8 per 10 000 with no significant difference by sex or level of education. Follow-up of the sample for three months gave an estimated annual incidence of rheumatic fever of 4 per 10 000. The positive predictive value of definite murmurs for diagnosis of cardiovascular disease was 35.21% for school health physicians and 86.67% for regional physicians. The results show that rheumatic fever and rheumatic heart disease are not major public health problems in Oman. The study recommends integration of the management and control of the diseases within the primary health care system