Mogens Hauge

The Danish twin register.

BACKGROUND Population based twin registers represent a valuable tool for genetic epidemiological research, since twin studies aim at separating the effect of genes and environment for complex traits. The Danish Twin Registers history, size, ascertainment and completeness of data, as well as data accessibility and availability are described. RESULTS The Danish Twin Register comprises 14,051 twin pairs born 1870-1930, representing all twins surviving to age six years, and 20,888 twin pairs born 1953-1982, representing 75% of those born 1953-1967 and 95% of those born 1968-1982. The birth cohorts 1931-1952 og 1983-1993 are being ascertained at the moment. The register is available for research given certain conditions are fulfilled. CONCLUSION This register will in a few years be the most comprehensive twin register in the world. It is a very valuable Danish research resource.

Facial clefts in sibs and children of epileptic patients

The prevalence of facial clefts in sibs and children of 2,072 epileptics ascertained in a defined region was determined by record linkage with a national cleft register, which also provided expected figures. Observed/expected ratios were increased only for cleft lip with or without cleft palate if the mother had manifested epilepsy: it was 4.7 when anticonvulsants were given before and during pregnancy, 2.7 in cases with no treatment, and zero in children born prior to maternal epilepsy. Children of epileptic men and sibs of epileptics showed no increase. The prevalence of isolated cleft palate was not above expectation in any group.

Prevalence of Fasting Hyperglycemia and Known Non-Insulin-Dependent Diabetes Mellitus Classified by Plasma C-Peptide: Fredericia Survey of Subjects 60–74 Yr Old

A Danish population of 5699 individuals (60–74 yr old) was screened by fasting blood glucose (FBG) and interviewed about known diabetes. The distribution of FBG in individuals not known to have diabetes showed no sex difference or significant variation with age. Fasting hyperglycemia (FH), defined as FBG ≥ 7 mM in subjects without a history of diabetes, was found in 1.7% of men and women. Known diabetes (KD) had a prevalence of 3.9 and 5.0% in men and women, respectively. The prevalence rates of FH and KD increased significantly with age. In the two subgroups, plasma C-peptide was measured after overnight fasting and subsequently 6 min after an intravenous injection of glucagon. Based on the distribution of the C-peptide concentrations in non-insulin-treated KD subjects, lower limits for non-insulin-dependent diabetes mellitus (NIDDM) of 0.30 pmol/ml for fasting C-peptide and 0.60 pmol/ml for stimulated C-peptide were arbitrarily chosen. According to these cutoff points, only 38.5% of KD subjects treated with insulin had insulin-dependent diabetes mellitus, corresponding to 9.3% of all KD subjects. After exclusion of these patients, the prevalence of recognized NIDDM was 3.5% in men and 4.5% in women. All FH subjects except one had C-peptide values in the NIDDM interval. A close agreement between fasting and glucagon-stimulated C-peptide was seen. In epidemiological studies with an expected high prevalence of NIDDM, we propose to use fasting C-peptide for classification of patients with insulin-treated diabetes.