Biomedical subjects

K Brusgaard

Publications and source records attributed to K Brusgaard.

At least 19 recordsLinked to original sources

PubMed2006

Molecular genetic analysis of 1053 Danish individuals with clinical signs of familial hypercholesterolemia.

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.

Apolipoprotein B-100↗

PubMed2005

Hyperinsulinemic hypoglycemia in Beckwith-Wiedemann syndrome due to defects in the function of pancreatic beta-cell adenosine triphosphate-sensitive potassium channels.

BACKGROUND: Beckwith-Wiedemann syndrome (BWS) is a congenital overgrowth syndrome that is clinically and genetically heterogeneous. Hyperinsulinemic hypoglycemia occurs in about 50% of children with BWS and, in the majority of infants, it resolves spontaneously. However, in a small group of patients the hypoglycemia can be persistent and may require pancreatectomy. The mechanism of persistent hyperinsulinemic hypoglycemia in this group of patients is unclear. PATIENTS AND METHODS: Using patch-clamp techniques on pancreatic tissue obtained at the time of surgery, we investigated the electrophysiological properties of ATP-sensitive K(+) (K(ATP)) channels in pancreatic beta-cells in a patient with BWS and severe medically-unresponsive hyperinsulinemic hypoglycemia. RESULTS: Persistent hyperinsulinism was found to be caused by abnormalities in K(ATP) channels of the pancreatic beta-cell. Immunofluorescence studies using a SUR1 antibody revealed perinuclear pattern of staining in the BWS cells, suggesting a trafficking defect of the SUR1 protein. No mutations were found in the genes ABCC8 and KCNJ11 encoding for the two subunits, SUR1 and KIR6.2, respectively, of the K(ATP) channel. Genetic analysis of this patients BWS showed evidence of mosaic paternal isodisomy. CONCLUSIONS: In this novel case of BWS with mosaic paternal uniparental disomy for 11p15, persistent hyperinsulinism was due to abnormalities in K(ATP) channels of the pancreatic beta-cell. The mechanism/s by which mosaic paternal uniparental disomy for 11p15 causes a trafficking defect in the SUR1 protein of the K(ATP) channel remains to be elucidated.

ATP-Binding Cassette Transporters↗

PubMed2005

Clinical symptoms according to genotype amongst patients with hereditary haemorrhagic telangiectasia.

BACKGROUND: Hereditary haemorrhagic telangiectasia (HHT) is a dominantly inherited disease, characterized by a wide variety of clinical manifestations, including epistaxis, gastrointestinal (GI) bleeding, pulmonary arteriovenous malformations (PAVMs) and neurological symptoms. HHT is a genetically heterogeneous disorder involving at least two loci; HHT 1 mapping to chromosome 9 q 34.1 (ENG) and HHT 2 mapping to chromosome 12 q 31 (ALK-1). OBJECTIVE: To evaluate and describe the diversity of clinical manifestations in a Danish population of HHT patients with known HHT 1 or HHT 2 subtype. DESIGN: Prospective clinical examination with genetic evaluation and follow-up. SETTING: Investigation centre was Odense University Hospital. All HHT patients in the County of Fyn were included. METHODS: HHT family members were invited to a clinical examination including registration of HHT manifestations, screening for PAVM and neurological evaluation. Blood tests were performed for analysis of disease-causing mutation, and clinical manifestations in the HHT subtypes were compared. The survival of the patients was studied in the follow-up period. RESULTS: Included in the study were 73 HHT patients representing 18 families. In 14 of the families we identified a disease-causing mutation. Thirty-nine patients (from 10 families) had HHT1 and 16 HHT patients from four families had HHT2. CONCLUSION: Amongst patients with HHT1 genotype the prevalence of PAVM was higher than amongst HHT patients with HHT2 genotype. HHT1 patients had experienced more severe GI bleeding than HHT2 patients. There was no significant difference in severity of epistaxis or age at debut. Finally the mortality over a 90-month observation period was not significantly increased.

Activin Receptors, Type I↗

PubMed2004

Significantly higher adrenocorticotropin-stimulated cortisol and 17-hydroxyprogesterone levels in 337 consecutive, premenopausal, caucasian, hirsute patients compared with healthy controls.

OBJECTIVE: To investigate whether elevated ACTH-stimulated 17-hydroxyprogesterone (17OHP) levels are caused by CYP21 genetic defects or by a general adrenal hyperresponsiveness in hirsute patients. METHODS: A total of 337 hirsute patients were evaluated by Ferriman-Gallwey score, serum testosterone, ACTH-stimulated 17OHP, and cortisol during the follicular phase. A cutoff value of 16 nmol/liter for maximum ACTH-stimulated 17OHP (M17OHP) responses was defined as the upper limit of the 95% confidence interval (CI) for the 97.5 percentile in 42 female controls. All patients were offered total screening of the CYP21 gene, and 252 healthy, premenopausal women with regular menses underwent genetic screening. RESULTS: Patients were divided into idiopathic hirsutism (IH) (n = 180) and polycystic ovary syndrome (PCOS) (n = 157) groups. M17OHP levels were significantly higher in IH [geometric mean value (nmol/liter +/- 2 sd) 12.2 (4.6-32.3)] and PCOS [11.9 (5.3-27.2)] compared with controls [8.5 (5.1-14.2)] (P < 0.001). A similar percentage of IH and PCOS patients had elevated M17OHP (20.5 vs. 20.8%, not significant), and these also had significantly higher 30-min cortisol levels compared with controls (P < 0.05). The prevalence of CYP21 mutations in patients was 8.6% compared with 6.3% in controls (P = 0.38). Ten of 19 carriers had M17OHP levels below the cutoff limit. CONCLUSION: The significantly higher ACTH-stimulated levels of cortisol and 17OHP in hirsute patients indicated adrenal hyperresponsiveness in IH and PCOS. CYP21-carrier status could not explain the observed high prevalence of abnormal ACTH-stimulated 17OHP levels in the hirsute population.

17-alpha-Hydroxyprogesterone↗

PubMed2004

Mutations in endoglin and in activin receptor-like kinase 1 among Danish patients with hereditary haemorrhagic telangiectasia.

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.

Activin Receptors, Type I↗

PubMed2003

New mutations in the lipoprotein lipase gene in a young boy with chylomicronaemia syndrome and in his family.

UNLABELLED: The case is reported of a 4-y-old boy with chylomicronaemia syndrome, under treatment with a low-fat diet and medium-chain triglycerides. The clinical and biochemical characteristics of the patient and 11 members of his family were studied. Lipoprotein profile, lipoprotein lipase (LPL) mass and activity were evaluated. Nucleotide substitutions in LPL promoter and exons were screened. The proband presented with severe hypertriglyceridaemia (triglycerides = 13.25 mmol l(-1)) and non-detectable LPL activity and mass. The boy was a compound heterozygote for four molecular defects in the LPL gene, two of which have not been reported before (CGT764 CTT/Arg170 --> Leu; GGA1482 --> GGT/Gly409 --> Gly). Among the family members, the proband was the only one who carried two genetic variants that modify LPL amino acid composition. CONCLUSION: The association of different alterations in the LPL gene could be a key factor in causing the severe phenotype observed. Moreover, treatment with a low-fat diet and medium-chain triglycerides failed to normalize the patient's hypertriglyceridaemia.

Anemia↗

PubMed2002

Effect of insulin on protein phosphatase 2A expression in muscle in type 2 diabetes.

BACKGROUND: Protein phosphatase 2A (PP2A) acts on a number of enzymes involved in the insulin regulation of glucose uptake and glycogen synthesis. This study was carried out to investigate the effect of insulin on PP2A expression in skeletal muscles of type 2 diabetic and control subjects. MATERIAL AND METHODS: Ten type 2 diabetic and 10 matched, control subjects were studied using the euglycaemic-hyperinsulinaemic clamp technique combined with indirect calorimetry. Immunoreactive protein levels of the catalytic alpha subunit of PP2A (PP2A-C alpha) were measured in biopsies from the vastus lateralis muscle obtained in the basal and insulin-stimulated state. RESULTS: In type 2 diabetic subjects insulin-mediated glucose disposal, glucose oxidation and nonoxidative glucose metabolism were reduced, whereas lipid oxidation was increased (all P < 0.05). Insulin down-regulated PP2A-C alpha expression in skeletal muscle of the control subjects (P < 0.05) but not in the type 2 diabetic subjects. In the control subjects, the insulin-mediated decrease in PP2A-C alpha correlated with the insulin-mediated increase in glucose disposal, glucose oxidation, nonoxidative glucose metabolism (all P < 0.05) and decrease in lipid oxidation (P < 0.01). In the type 2 diabetic subjects these relationships were absent. CONCLUSIONS: Down-regulation of PP2A-C alpha expression by insulin in skeletal muscle seems to be associated with a normal insulin action on glucose storage, glucose and lipid oxidation. Impaired down-regulation of PP2A-C alpha expression by insulin may be a marker for insulin resistance and contribute to the pathogenesis of type 2 diabetes.

Biomarkers↗

PubMed2001

[Congenital hyperinsulinism].

In the last five years, our knowledge about the heterogenous syndrome of congenital hyperinsulinism (HI) has expanded explosively. HI may be familiar or sporadic, mild or severe, transitory or persistent, and histologically focal or diffuse. At least 63 disease-causing mutations have been found in the genes for the beta cell's ATP-dependent potassium channel, whose elements are the sulphonylurea receptor, SUR1, and Kir6.2. Other mutations cause enhancement of the glucose-stimulated ATP production in the beta cell. The resulting non-functional, or closed, potassium channel causes hypersecretion of insulin. Genetic screening has succeeded in detecting mutations in less than 50% of HI-patients. Genotype-phenotype relations, diagnosis and treatment are reviewed.

Genetic Testing↗

PubMed2001

Mutations in the ALK-1 gene and the phenotype of hereditary hemorrhagic telangiectasia in two large Danish families.

Mutations in the ENG gene on chromosome 9 (HHT 1) and in the ALK-1 gene on chromosome 12 (HHT 2) have been reported as causes of hereditary hemorrhagic telangiectasia (HHT). HHT 1 has been correlated with a higher prevalence of pulmonary arteriovenous malformations than HHT 2. Other distinct phenotype-genotype correlations have not been described. The prevalence of HHT in the county of Fyn, Denmark, was 15.6 per 100,000 on January 1, 1995. All living patients and their first-degree relatives were invited to attend a detailed clinical examination and blood was drawn for mutation analysis. In two families mutations were identified in exon 8 of the ALK-1 gene. In family 6 we found a T1193A mutation. In this family a high prevalence of PAVM and severe GI bleeding was documented, while in family 8 with a C1120T mutation no individuals with PAVM were identified and only one patient had a history of severe GI bleeding. No mutations in the endoglin locus were found in either family.

Activin Receptors↗

PubMed2000

Predominance of a 6 bp deletion in exon 2 of the LDL receptor gene in Africans with familial hypercholesterolaemia.

In South Africa, the high prevalence of familial hypercholesterolaemia (FH) among Afrikaners, Jews, and Indians as a result of founder genes is in striking contrast to its reported virtual absence in the black population in general. In this study, the molecular basis of primary hypercholesterolaemia was studied in 16 Africans diagnosed with FH. DNA analysis using three screening methods resulted in the identification of seven different mutations in the coding region of the low density lipoprotein (LDLR) gene in 10 of the patients analysed. These included a 6 bp deletion (GCGATG) accounting for 28% of defective alleles, and six point mutations (D151H, R232W, R385Q, E387K, P678L, and R793Q) detected in single families. The Sotho patient with missense mutation R232W was also heterozygous for a de novo splicing defect 313+1G-->A. Several silent mutations/polymorphisms were detected in the LDLR and apolipoprotein B genes, including a base change (g-->t) at nucleotide position -175 in the FP2 LDLR regulatory element. This promoter variant was detected at a significantly higher (p<0.05) frequency in FH patients compared to controls and occurred in cis with mutation E387K in one family. Analysis of four intragenic LDLR gene polymorphisms showed that the same chromosomal background was identified at this locus in the four FH patients with the 6 bp deletion. Detection of the 6 bp deletion in Xhosa, Pedi, and Tswana FH patients suggests that it is an ancient mutation predating tribal separation approximately 3000 years ago.

Adolescent↗

PubMed1999