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The Determination of Atrial Natriuretic Peptide (ANP) by Radioimmunoassay in Diabetes Mellitus Dai Qing Lin, Li Mae Len et al. Jiu Xian Qiao Hospital, Beijing Research Institute of Hypertension and Diabetes, Beijing, People's Republic of China

The levels of ANP determined with the specific RIA in 64 cases of diabetes and 71 healthy subjects were 277.27±169.33 pg/ml and 378.1i169.2 pg/ml, respectively. In the meantime, the concentrations of angiotensin II, aldosterone, potassium and sodium in plasma were detected in diabetic patients and healthy subjects. Of 64 patients, the mean concentration of ANP was 323.6i178.18 pg/ml in 25 cases without diabetic chronic complications, and 246.79±144.3 pg-ml in 39 cases with diabetic chronic complications, P~0.OI. The concentration of ANP in 58 NIDDM patients was significantly less than that in healthy subjects, P<0.01. But no statistical significance between IDDM and healthy subjects.

Our data show that the level of ANP in diabetes was lower than healthy subjects. It was a significant decrease in NIDDM patients with chronic complications. The concentration of ANP was not affected by the level of plasma glucose.

This abstract was published in the Proceedings of The First Symposium on Diabetes Mellitus between China and Japan, May 5-6, 1987, Beijing.

S-3-7 THE IMMUNOGENETICS OF IDDM IN CAUCASIAN EUROPE T. Wilkin Endocrine Section, Dept Medicine II, General Hospital, Southampton

A high family frequency of diabetes was noted long before type I diabetes (IDDM) was recognised to be autoimmune. Nevertheless, only about 40% of identical twin pairs are concordant for IDDM, suggesting that environmental factors play an important role in determining clinical expression of the susceptibility. Certain HLA haplotypes, in particular HLA DR3 and/or DR4, occur in 95% Caucasian IDD's, but are not clinically useful markers because they are very common in the general population. Furthermore, the genes which code for HLA are not the genes which cause diabetes and DR4, for example, can be coded on at least seven different haplotypes, some of which do not incorporate IDDM susceptibility genes. Tissue typing is further limited by the failure of serology to identify certain D-region antigens such as DP. As a result, sero-typing is giving way to genotyping by Southern analysis of gene polymorphisms, and much interest is currently focused on polymorphisms of restriction fragments incorporating the DQB chain gene° The DQ gene products are thought to be important in the T cell recognition processes which initiate the immune response, and the finding that certain DQ poly- morphisms are several times more discriminating for IDDM than DR, suggests that DQ products have a closer functional relationship with autoimmunity.

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