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Concentrations of triglycerides and cholesterol in serum and the distribution of plasma lipoprotein fractions have been studied in 25 patients with chronic non‐nephrotic renal failure. Hyperlipoproteinemia was demonstrated in 17 of them (type II 1 case, type III 1 case, type IV 13 cases, type V 2 cases). None of the recognized causes of secondary hyperlipoproteinemia appeared to be responsible for this high incidence. In 19 patients the i.v. glucose tolerance test showed abnormal responses. For patients with 24‐hour urinary losses of protein exceeding 3.5 g a statistically significant (inter‐patient) correlation was found between the concentration of triglyceride in serum and the rate of renal protein excretion. Including patients with milder degrees of proteinuria this relationship was obscured, and no further correlation could be established between serum lipid values and proteinuria, renal function or glucose tolerance. 1972 Association for the Publication of the Journal of Internal Medicine

We have recently developed a simple mutation screening assay based on the denaturing gradient gel electrophoresis (DGGE) technique for detection of mutations in the coding and regulatory regions of the low density lipoprotein receptor (LDLR) gene and the codon 3500 region of the apolipoprotein (apo) B-100 gene leading to familial hypercholesterolemia (FH) and familial defective apo B-100 (FDB), respectively. To evaluate the assay, 14 Danish families suspected of FH were studied. In ten families, the DGGE assay detected seven different point mutations, including mutations undescribed prior to establishing the assay. In addition, in one of these ten families and in one of the remaining four families, Southern blotting detected the FH-DK3 exon 5 deletion. Based on segregation analysis and clinical data, the FH diagnosis was dubious in the remaining three families without DGGE or Southern blotting detectable mutations. In conclusion, a simple DGGE based mutation screening assay may detect underlying mutations in most FH/FDB families, thus allowing its routine use in genetic counselling of FH-families.

The lipid disorder familial hypercholesterolemia (FH) predisposes to cardiovascular disease. With a prevalence of approximately one in 500 in the general Caucasian population, FH is one of the most frequent single-gene disorders. As the mutational spectra vary between populations, it is crucial to identify the mutations in a given population in order to implement a molecular genetic screening strategy. A total of 1053 referred individuals with clinical signs of FH were investigated, and mutations were identified in 425 individuals. Fifty-four different mutations were identified, of which 13 are novel. The five most frequent mutations accounted for 56.3% of all disease-causing mutations. The majority of the remaining mutations were of a private nature only encountered in single families. In this study, a reliable molecular genetic screening protocol was established, and the relevance of performing presymptomatic genetic analysis as part of a preventive strategy was documented. We have acquired knowledge of the mutational spectra in the Danish population and thus will be able to trace mutations in their relatives through our index cases.

Hereditary haemorrhagic telangiectasia (HHT) is a rare disorder with one per 6000-10,000 affected individuals in the general Caucasian population. HHT is genetically heterogeneous, involving at least two loci HHT1 mapping to chromosome 9q34.1 and HHT2 mapping to chromosome 12q31. The loci have been identified as endoglin (ENG) and activin receptor-like kinase 1 (ALK1). In order to gain knowledge of the genotype distribution and prevalence in the Danish population and to establish a reproducible and sensitive molecular genetic test method, we developed a denaturating gradient gel electrophoresis protocol for mutation scanning of the two loci. Twenty-five Danish HHT families were tested. A total of eight new as well as seven previously reported mutations were identified. A founder mutation was characterized present in seven families and possibly introduced around 350 years ago. In one individual, a presumed spontaneous mutation was characterized. The method developed proved to be very sensitive for mutation detection in both ENG and ALK1. Genetic screening in HHT families facilitates an early treatment strategy for silent HHT manifestations in first degree relatives.

Aims CYP2D6 and CYP2C19 are polymorphically expressed enzymes that show marked interindividual and interethnic variation. The aim of this study was to determine the frequency of the defective alleles in CYP2D6 and CYP2C19 in Africans and to test whether the genotype for CYP2C19 is better correlated with the proguanil/cylcoguanil ratio than the mephenytoin S/R ratio. Methods Two hundred and sixteen black Tanzanians were phenotyped for CYP2D6 with the use of sparteine, and for CYP2C19 with the use of mephenytoin and proguanil. Of these 196 subjects were also genotyped for CYP2D6 (including the CYP2D6*1, CYP2D6*3 and CYP2D6*4 alleles) and 195 were genotyped for CYP2C19 (including the CYP2C19*1, CYP2C19*2 and the CYP2C19*3 alleles). Furthermore 100 subjects were examined for the allele duplication in CYP2D6, leading to ultrarapid metabolism, with long PCR. Results The sparteine metabolic ratio (MR) was statistically significantly higher in the Tanzanian group of homozygous, extensive metabolizers compared to a historical control group of white Danish extensive metabolizers. Only one poor metabolizer for CYP2D6 (MR=124 and genotype CYP2D6*1/CYP2D6*4 ) was found. The gene frequencies were 0.96 for the CYP2D6*1 allele and 0.04 for the CYP2D6*4 allele. No CYP2D6*3 alleles were found. Nine subjects had an allele duplication in CYP2D6 (9%). For CYP2C19 there were seven subjects (3.6%) who were phenotyped as poor metabolizers, but only three subjects (1.5%) had a genotype (CYP2C19*2/CYP2C19*2 ) indicative of poor metabolism. The gene frequencies were 0.90 for the CYP2C19*1 allele and 0.10 for the CYP2C19*2 allele. No CYP2C19*3 alleles were found. The mephenytoin S/R ratios were not bimodally distributed. Conclusions Both the genotyping and phenotyping results show that there is a substantial difference between an African black population and a Caucasian population in the capacity to metabolize drugs via CYP2D6 and CYP2C19.

Hereditary haemochromatosis is an autosomal recessive disease that is genetically expressed by excessive accumulation of iron in the tissues, resulting in cirrhosis, diabetes mellitus, cardiomyopathy and hypogonadism. As the disease may be diagnosed before the appearance of symptoms, and prevented by repeated phlebotomies, there are strong implications for adoption of a screening procedure. Determinations of transferrin saturation (TS) and serum ferritin concentration (SF) were used to screen 4302 blood donors, who were selected for follow-up studies if they fulfilled any of the following three criteria: (i) TS greater than or equal to 0.7; (ii) TS greater than or equal to 0.5 together with SF greater than or equal to 150 micrograms l-1; (iii) SF greater than or equal to 300 micrograms l-1. A total of 58 subjects who fulfilled at least one of these criteria were reinvestigated, after which 18 individuals still fulfilled at least one criterion. Fifteen subjects having SF greater than or equal to 300 micrograms l-1 were offered liver biopsy and thirteen of these accepted. In one individual, no stainable iron was detected, and two subjects did not fulfil the previously established diagnostic criteria for the diagnosis of hereditary haemochromatosis. Ten subjects who had a high TS and liver iron grade 2-4 according to Bassett were classified accordingly as homozygotes. On the basis of these results, the prevalence of haemochromatosis in Denmark was estimated to be 0.0037-0.0046.

The pH‐dependent chemical shift behavior in 31P NMR spectroscopy of inorganic phosphate (P1) and methylphosphonic acid (MeP) in solutions of various composition at 37°C are presented. An ionic strength dependent lowering of the pKa. values of both P1 and MeP is observed. 3 mmol/liter Mg2+ did not affect the pH‐dependent chemical shift behavior of P1 and MeP in solutions containing 135 mmol/liter KCl and 5 mmol/liter NaCl. This finding: was reinforced by adding 5 mmol/liter 2,3‐diphosphoglycerate (2,3‐DPG) and 1.5 mmol/liter ATP to solutions with 3 mmol/liter Mg2+. The presence of these Mg+‐binding substances had no detectable effect on the chemical shift of P1 and MeP at various pH values The pH dependence of the chemical shift of MeP, P1 and 2,3‐DPG in oxygenated erythrolysates was compared to protein free model solutions. No significant differences could be detected for MeP and P1 whereas there was a change in the chemical shift of about 0.1–0.2 ppm for both phosphates in 2,3‐DPG. Finally intracellular pH estimated by 31P NMR were compared to pH measured by electrode in freeze‐thawed hemolysates. At an extracellular pH of 7.341 ± 0.045 (SD) (n = 6) the intracellular pH was 7.160 ± 0.014 (SD) by the freeze‐thaw procedure and 7.213 ± 0.027 (SD), 7.172 ± 0.029 (SD), and 7.152 ± 0.033 (SD) estimated by the chemical shift of MeP, and 3‐phosphorus and 2‐phosphorus of 2,3‐DPG, respectively. © 1987 Academic Press, Inc.