Is there a relationship between stature and age of onset of type 2 Diabetes?

AIMS: MSP1A and MSP1B polymorphic sites located in the GH genomic area have been found associated with GH response to insulin stimulation, with familiar short stature and with age at onset of Type 2 Diabetes (T2D). These observations prompted us to search for a possible relationship between stature and age at onset of the disease. METHODS: We have reexamined the data of 272 subjects with T2D mellitus. RESULTS: There is a highly significant negative correlation between stature and age at onset in non obese females (p < 0.001) but not in obese females and in males. In non obese females with stature within the first quartile the mean age at onset is 62 years while in those with a stature greater than the first quartlile the mean age at onset is 52 yesrs (p < 0.001). No difference is observed in obese females and males. CONCLUSIONS: These observations suggest the existence of different mechanisms underlying susceptibility to T2D. In addition to the well known increased risk due to obesity, endocrine dysfunctions related to genetic variability within the GH genomic area could represent another mechanism operating in non obese females. A cluster of non obese women characterized by short stature and late onset of diabetes seems to be separated by this mechanism from other women.

Genetic polymorphism within human growth hormone gene region and BMI in type 2 diabetes.

Currently there is a surge of interest in the association of obesity with growth hormone (GH). Our hypothesis is that genetic variation within the hGH area could predispose to obesity in type 2 diabetes. We examined 68 Caucasian subjects with type 2 diabetes from the central area of Continental Italy. In these subjects we examined four polymorphic loci (Msp1A, Msp1B, BglIIA and BglIIB) located in the hGH gene region (chromosome 17q22-9-24). A sample of 192 adults from the population of Central Italy were studied as controls. Msp1B and Msp1A polymorphisms are associated with BMI. For both polymorphisms the proportion of overweight subjects is greater in the *1/*1 genotype than in carriers of the *2 allele (97% vs. 79% and 94% vs. 86% respectively). For both polymorphisms, the mean value of BMI is greater in the *1/*1 genotype than in carriers of the *2 allele. The mean values of age at onset of diabetes are greater in Msp1B*1/*1 and Msp1A*1/*1 genotypes than in carriers of the *2 allele. BglIIA and BglIIB polymorphisms are not associated with being overweight. The present study suggests that the structural organisation of the hGH genomic area may have an important role in being overweight associated with type 2 diabetes.

Diabetic complications and the genetics of signal transduction. A study of retinopathy in NIDDM.

Cytosolic low molecular weight acid phosphatase (ACP1) is a high polymorphic phosphotyrosine-protein-phosphatase involved in signal transduction. In NIDDM subjects we have found that ACP1 genotype is a highly significant predictor of retinopathy, suggesting that genetic variability of signal transduction may have an important role in the susceptibility to this complication. Adenosine deaminase, ABO blood groups and several clinical variables have been also considered. The results point out the importance of interactions between genetic systems. Among non-genetic variables dislipidemia and treatment with insulin are significantly associated with retinopathy.

Phosphotyrosine-protein-phosphatase and diabetic disorders. Further studies on the relationship between low molecular weight acid phosphatase genotype and degree of glycemic control.

We have studied a new sample of 276 NIDDM patients from the population of Penne (Italy). Comparison of the new data with those of 214 diabetic pregnant women from the population of Rome reported in a previous paper has shown that the pattern of association between low molecular weight acid phosphatase genotype and degree of glycemic control is similar in the two classes of diabetic patients. Among nonobese subjects the proportion of ACP1*A (the allele showing the lowest enzymatic activity) is lower in diabetic patients with high glycemic levels (mean value greater than 8.9 mmol/l) than in diabetic patients with a low glycemic level (mean value less than 8.9 mmol/l). Among obese subjects no significant association is observed between glycemic levels and ACP1. Among nonobese subjects the concentration of f isoform of ACP1 is higher in patients showing a high glycemic level than in patients showing a low glycemic level. No significant difference is observed for s isoform.

A study of human growth hormone and insulin gene regions in relation to metabolic control of non-insulin-dependent diabetes mellitus.

The possible association of human growth hormone (hGH) and insulin (INS) gene regions with metabolic control in diabetes was investigated in 98 subjects with non-insulin-dependent diabetes mellitus (NIDDM); 54 control subjects from the same population were also studied. Two polymorphic restriction sites in the region of the hGH cluster (BGLIIA and BGLIIB) show significant association with both glycemic and hemoglobin A1c (HbA1c) levels. Mean values for plasma glucose and HbA1c show a maximum in the BGLIIA *1/*1 genotype and a minimum in the BGLIIA *2/*2 genotype. Mean values for plasma glucose and HbA1c show a maximum in the BGLIIB *1/*2 genotype. The BGLIIA*2/BGLIIB*1 haplotype shows a negative correlation with plasma glucose and HbA1c levels. Since the two markers are located in the area surrounding the hGH-V locus, the expression of this gene in NIDDM warrants further investigation.

Type 2 diabetes and the genetics of signal transduction: a study of interaction between adenosine deaminase and acid phosphatase locus 1 polymorphisms.

Acid phosphatase locus 1 (ACP1) is a highly polymorphic enzyme that has an important role in flavoenzyme activity and in the control of insulin receptor activity and band 3 protein phosphorylation status. Adenosine deaminase (ADA) is a polymorphic enzyme that catalyses the irreversible deamination of adenosine to inosine and has an important role in regulating adenosine concentration. Based on the hypothesis that ACP1 counteracts insulin signaling by dephosphorylating the insulin receptor and that adenosine has an anti-insulin action, we reasoned that low ACP1 activity (low dephosphorylating action on insulin receptor) when associated with high ADA activity (low adenosine concentration) would result in a cumulative effect towards an increased glucose tolerance. On the contrary, high ACP1 activity when associated with low ADA activity would result in a cumulative effect towards a decreased glucose tolerance. A total of 280 adult subjects with type 2 diabetes from the population of Penne (Italy) were studied. There was a nonsignificant trend toward an increase in the proportion of subjects with the complex type with high ACP1 activity and low ADA activity (ie, *B/*B; *A/*C; *B/*C; *C/*C//ADA*1/*2 and *2/*2) in type 2 diabetes relative to that observed in newborn infants from the same population. High ACP1 activity/low ADA activity joint genotype was positively associated with high glycemic levels and with high body mass index (BMI) values. Low ACP1 activity/high ADA activity joint genotype was also positively associated with dyslipidemia. These findings suggest that both ACP1 and ADA contribute to the clinical manifestations of type 2 diabetes and probably also have a marginal influence on susceptibility to the disease. Both additive and epistatic interactions between the 2 systems seem to be operative.

Low-molecular-weight acid phosphatase (ACP1), obesity, and blood lipid levels in subjects with non-insulin-dependent diabetes mellitus.

Low-molecular-weight acid phosphatase (ACP1) is a polymorphic protein-tyrosine phosphatase present in all human tissues, including adipocytes. A positive association between the low-activity ACP1*A/*A genotype and extreme body mass index has previously been shown by us in obese subjects from the population of Rome. We have now studied a sample of 265 subjects with non-insulin-dependent diabetes mellitus (NIDDM) from another Italian population. There is a significant interaction between ACP1, body mass index, and blood lipid level. A highly significant positive association between ACP1*A/*A and high body mass index similar to that previously observed in obese subjects from the population of Rome is present only in those NIDDM subjects with blood lipid levels within the normal range. In NIDDM subjects the low-activity ACP1*A/*A variant seems to favor the increase of body mass or blood lipid levels or both. The pattern of association is independent of sex, age at survey, age at onset of diabetes, duration of disease, and therapy.

RH blood groups and diabetic disorders: is there an effect on glycosylated hemoglobin level?

Recent cloning of RH genes has elucidated their structure, suggesting that RH proteins are part of an oligomeric complex with transport function in the erythrocyte. This observation prompted us to investigate a possible relationship between the RH system and the glycosylated hemoglobin level (Hb A(1c)) in diabetes. This compound is considered an important indicator- of glycemic control in diabetic disorders. We studied 278 subjects with non-insulin-dependent diabetes mellitus (NIDDM) from the population of Penne, Italy. Glycemic and glycosylated hemoglobin (Hb A(1c)) levels are associated with RH phenotype. Glucose and Hb A(1c) levels are increased in DCcEe subjects and decreased in ddccee subjects as compared to the mean values for other genotypes. Sex, age at onset of disease, duration of disease, and age of patients were also considered. Correlation analysis suggests that these variables influence glycemia directly and Hb A(1c) indirectly. The RH system, on the other hand, seems to influence the Hb A(1c) level directly. Preliminary data on 53 children with insulin-dependent diabetes mellitus (IDDM) from Sardinia seem to confirm the relationship between RH and Hb A(1c) observed in NIDDM. Since glycosylated hemoglobin is found inside red blood cells, the relationship between RH genetic variability and Hb A(1c) level suggests that RH proteins may influence glucose transport through red cell membrane and/or hemoglobin glycation.

Phosphotyrosine protein phosphatases and diabetic pregnancy: an association between low molecular weight acid phosphatase and degree of glycemic control.

Low molecular weight acid phosphatase encoded by the highly polymorphic locus ACP1 is a member of the protein-tyrosin phosphatase family (PTPases) which plays an essential role in the control of receptor signalling through phosphotyrosine pathways. Recent experiments have shown that purified rat liver ACP, corresponding to human ACP1, is able to hydrolyze a phosphotyrosine-containing synthetic peptide corresponding to the 1146-1158 sequence of the human insulin receptor, and shows a high affinity for it. This prompted us to analyze the degree of glycemic control in relation to ACP1 genetic variability in a sample of 214 diabetic pregnant women including IDDM, NIDDM and gestational diabetes. The ACP1 genotype was also determined in 482 non-diabetic pregnant women. In diabetic women glycemic levels in the last trimester of pregnancy appear to be significantly associated with the ACP1 genotype, and correlate positively with ACP1 enzymatic activity. The data suggest that quantitative variations of ACP1 may influence the clinical manifestations of diabetic disorders, and call for further studies on the role of this enzyme in the modulation of insulin-receptor phosphotyrosine pathways.