Huygens W, Thomis MA, Peeters MW, Aerssens J, Janssen RG, Vlietinck RF, Beunen G. A quantitative trait locus on 13q14.2 for trunk strength. Twin Res. 2004 Dec;7(6):603-6. 

Joossens S, Vermeire S, Van Steen K, Godefridis G, Claessens G, Pierik M, Vlietinck R, Aerts R, Rutgeerts P, Bossuyt X. A quantitative trait locus on 13q14.2 for trunk strength. Inflamm Bowel Dis. 2004 Nov;10(6):771-7.  


Vos MA, Paulussen AD. Genetic basis of drug-induced arrhythmias. Ann Med. 2004;36 Suppl 1:35-40.


Van Den Bosch BJ, De Coo IF, Hendrickx AT, Busch HF, De Jong G, Scholte HR, Smeets HJ Increased risk for cardiorespiratory failure associated with the A3302G mutation in the mitochondrial DNA encoded tRNA(Leu(UUR)) gene. Neuromuscul Disord. 2004 Oct;14(10):683-8.


Knaapen AM, Ketelslegers HB, Gottschalk RW, Janssen RG, Paulussen AD, Smeets HJ, Godschalk RW, Van Schooten FJ, Kleinjans JC, Van Delft JH. Simultaneous genotyping of nine polymorphisms in xenobiotic-metabolizing enzymes by multiplex PCR amplification and single base extension. Clin Chem. 2004 Sep;50(9):1664-8.  


Geithner CA, Thomis MA, Eynde BV, Maes HH, Loos RJ, Peeters M, Claessens AL, Vlietinck R, Malina RM, Beunen GP Related Articles Growth in Peak Aerobic Power during Adolescence. Med Sci Sports Exerc. 2004 Sep;36(9):1616-1624.

Yarden J, Radojkovic D, De Boeck K, Macek M Jr, Zemkova D, Vavrova V, Vlietinck R, Cassiman JJ, Cuppens H. Polymorphisms in the mannose binding lectin gene affect the cystic fibrosis pulmonary phenotype. J Med Genet. 2004 Aug;41(8):629-33.  

Pierik M, Vermeire S, Steen, KV, Joossens S, Claessens G, Vlietinck R & Rugeerts P. Tumour necrosis factor-alfa receptor 1 and 2 polymorphisms in inflammatory bowel disease and their association with repsonse to infliximab. Aliment Pharmacol Ther. Aug 2004; 20:1-8  


Vermeire S, Rutgeerts P, Van Steen K, Joossens S, Claessens G, Pierik M, Peeters M, Vlietinck R. Genome wide scan in a Flemish inflammatory bowel disease population: support for the IBD4 locus, population heterogeneity, and epistasis. Gut. 2004 Jul;53(7):980-6.

Jan R. Brants, Torik A.Y. Ayoubi, Kiran Chada, Wim J. M. Van de Ven and Marleen M. R. Petit. Differential regulation of the insulin-like growth factor II mRNA-binding protein genes by architectural transcription factor HMGA2. FEBS Lett. 2004 Jul 2;569(1-3):277-83.  

Thomis MA, Huygens W, Heuninckx S, Chagnon M, Maes HH, Claessens AL, Vlietinck R, Bouchard C, Beunen GP.Exploration of myostatin polymorphisms and the angiotensin-converting enzyme insertion/deletion genotype in responses of human muscle to strength training. Eur J Appl Physiol. 2004

Zeegers MP, Rijsdijk F, Sham P, Fagard R, Gielen M, De Leeuw PW, Vlietinck R. The contribution of risk factors to blood pressure heritability estimates in young adults: the East flanders prospective twin study. Twin Res. 2004 Jun;7(3):245-53.  

Huygens W, Thomis MA, Peeters MW, Aerssens J, Janssen R, Vlietinck RF, Beunen G. Linkage of myostatin pathway genes with knee strength in humans. Physiol Genomics. 2004 May 19;17(3):264-70.

Van de Putte B, Matthijs K, Vlietinck R. A social component in the negative effect of sons on maternal longevity in pre-industrial humans. J Biosoc Sci. 2004 May;36(3):289-97.

Huygens W, Thomis MA, Peeters MW, Vlietinck RF, Beunen GP Determinants and upper-limit heritabilities of skeletal muscle mass and strength. Can J Appl Physiol. 2004 Apr;29(2):186-200.


Zeegers MP, Poppel Fv F, Vlietinck R, Spruijt L, Ostrer H. Founder mutations among the Dutch. Eur J Hum Genet. 2004 Jul;12(7):591-600. 

Jacobs LJ, Jongbloed RJ, Wijburg FA, de Klerk JB, Geraedts JP, Nijland JG, Scholte HR, de Coo IF, Smeets HJ. Pearson syndrome and the role of deletion dimers and duplications in the mtDNA. J Inherit Metab Dis. 2004 March;27(1):47-55  


Jongbloed RJ, Marcelis CL, Doevendans PA, Schmeitz-Mulkens JM, Van Dockum WG, Geraedts JP, Smeets HJ. Variable clinical manifestation of a novel missense mutation in the alpha-tropomyosin (TPM1) gene in familial hypertrophic cardiomyopathy. J Am Coll Cardiol. 2003 Mar 19;41(6):981-6.  

Paulussen AD, Gilissen RA, Armstrong M, Doevendans PA, Verhasselt P, Smeets HJ, Schulze-Bahr E, Haverkamp W, Breithardt G, Cohen N, Aerssens J. Genetic variations of KCNQ1, KCNH2, SCN5A, KCNE1, and KCNE2 in drug-induced long QT syndrome patients. J Mol Med. 2004 Mar;82(3):182-8.  

Esters N, Pierik M, van Steen K, Vermeire S, Claessens G, Joossens S, Vlietinck R, Rutgeerts P. Transmission of CARD15 (NOD2) variants within families of patients with inflammatory bowel disease. Am J Gastroenterol. 2004 Feb;99(2):299-305.  


Van Larebeke N, Koppen G, Nelen V, Schoeters G, Van Loon H, Albering H, Riga L, Vlietinck R, Kleinjans J; Flemish Environment and Health Study Group.Differences in HPRT mutant frequency among middle-aged Flemish women in association with area of residence and blood lead levels.Biomarkers. 2004 Jan-Feb;9(1):71-84.

Drusedau M, Dreesen JC, De Die-Smulders C, Hardy K, Bras M, Dumoulin JC, Evers JL, Smeets HJ, Geraedts JP, Herbergs J. Preimplantation genetic diagnosis of spinocerebellar ataxia 3 by (CAG)(n) repeat detection. Mol Hum Reprod. 2004 Jan;10(1):71-5.


Marcus-Soekarman D, Hamers G, Velzeboer S, Nijhuis J, Loneus WH, Herbergs J, de Die-Smulders C, Schrander-Stumpel C, Engelen J. Mosaic trisomy 11p in monozygotic twins with discordant clinical phenotypes. Am J Med Genet A. 2004 Jan 30;124(3):288-91




Preimplantation Genetic Diagnosis in Maastricht: An overview.
J. Herbergs1, J. Dreesen1, E. Coonen2, C. De Die-Smulders1, J. Den Hartog2, M. Drüsedau1, J. Dumoulin2, G. De Wert3, J. Engelen1, J. Evers2, J. Geraedts1, H. Smeets1. 1) Clinical Genetics, Academic Hospital Maastricht, Maastricht, Netherlands; 2) Obstetrics & Gynaecology, Academic Hospital Maastricht, Maastricht, Netherlands; 3) Institute for Bioethics, Maastricht University, Maastricht, Netherlands. Preimplantation Genetic Diagnosis (PGD) is an alternative for prenatal diagnosis for couples at risk of transmitting a genetic disorder to their offspring. The genetic diagnosis of the early cleavage stage embryo can prevent couples from making the difficult decision of pregnancy termination in case of an affected foetus after prenatal diagnosis or can significantly increase the chance of an ongoing pregnancy, in case of recurrent pregnancy loss. PGD in Maastricht started at the end of 1994 with FISH sex selection soon followed by PCR analysis of a specific single gene disorder. The first FISH translocation analysis was done in 1997. In almost nine years 237 PGD cycles were started in 106 patients. In the first year PGD was performed for only two different X-linked disorders. Currently PGD sex selection has been performed for 19 different XL disorders. Furthermore, 14 different chromosomal aberrations have been diagnosed as well as 10 different single gene disorders. This involved 177 ovum pick ups (OPU) and the analysis of 1236 embryos. Of the analysed embryos 507 were either not affected by the disorder investigated or of the female gender in case of a sex selection. In 147 cycles an embryo transfer (ET) could be performed resulting in, 37 singleton, 9 twin and one triplet pregnancy, of which 6 ended in an early abortion. From the triplet pregnancy one child was a stillborn. In total 40 healthy babies were born with no major complications. Nine pregnancies are still ongoing. Conclusion: In the past years the number of PGD cycles and different disorders for which PGD can be offered has steadily grown and PGD has proved to be a successful alternative for prenatal diagnosis with pregnancy rates of 27% per OPU and 32% per ET.

Truncation of HERG proteins cause Long QT Syndrome in two Dutch families.
A.D.C. Paulussen1, A. Raes2, R.J. Jongbloed1, R.A.H.J. Gilissen3, A.A. Wilde4, D.J. Snyders2, H.J. Smeets1, J. Aerssens3. 1) Dept Genetics & Cell Biology, Univ Maastricht, Maastricht, The Netherlands; 2) Laboratory of Molecular Biophysics, Physiology and Pharmacology, University of Antwerp, Antwerp, Belgium; 3) Dept Drug Discovery, Jonhson & Johnson Research and Development, Beerse, Belgium; 4) Experimental and Molecular Cardiology Group, Academic Medical Centre, Amsterdam, The Netherlands. Background Long QT Syndrome (LQTS) is a ventricular arrhythmia, recognized by a prolongation on the ECG and which causes symptoms such as syncopes and sudden death. Six genes have been identified for this syndrome. Mutations in one of these genes, the KCNH2 (HERG) ion channel gene, are responsible for LQTS by causing a reduction of the delayed rectifier current IKr. This reduction delays repolarisation of cardiac cells and renders patients vulnerable to ventricular arrhythmias. Methods and Results We identified and characterized two heterozygous mutations (E698X and P872fs877) in the C-terminus of the KCNH2 gene in two Dutch LQTS families. Both mutations lead to premature truncations of the C-terminus of the HERG protein. Biochemical, confocal microscopy and electrophysiological techniques were used to investigate protein expression, trafficking and function. The E698X protein, lacking 461 amino acids, was expressed with reduced quantities en produced no currents in vitro. The P872fs877 protein, lacking 282 amino acids was expressed and functional. P872fs877 mutant channels produced currents with biophysical properties similar to WT channels. Heterologous co-expression of WT and P872fs877 subunits showed a complex functionality; during action potential clamp experiments the capacity of hERG current was increased from ~30 percent (homologous WT or mutant expression) to 70 percent. However, this positive effect was completely abolished by a high increase in ER-retention of heterotetramers. Conclusions LQTS in the first family is caused by haplo-insufficiency due to absence of E698X HERG proteins. LQTS in the second family is caused by ER retention due to heterotetramerization, which has a greater impact than the apparent gain in function of mutated channels.

Elucidation of pathogenic genetic pathways in the hypertrophic heart using microarray technology.
H. Smeets1, B. Van den Bosch1, P. Lindsey1, D. Lips2, C. Van den Burg1, P. Doevendans2, R. Vlietinck1. 1) Dept of Genetics & Cell Biol, Univ Maastricht, Maastricht, Netherlands; 2) Dept of Cardiology of the Heart Lung Centre Utrecht (UMCU), Utrecht, Netherlands. Introduction Gene expression differences between normal, hypertrophic and failing heart may unravel underlying pathogenic mechanisms in patients. To circumvent the complexity and scarcity of human biopsies, we used the Transverse Aortic Constricted (TAC) mouse model for cardiac hypertrophy. By gene expression profiling we aim at identifying the molecular program underlying myocardial hypertrophy, the most powerful predictor of heart failure. Methods Male Swiss mice (10 weeks old) were either TAC or sham-operated (n=5) and sacrificed at 48 hours, 1 week, 6 or 8 weeks after surgery. Hearts were harvested and hypertrophy was assessed by determining the ratio left ventricle weight/tibia length. Left ventricle RNA was analysed on microarrays containing 15,000 embryonic and fetal cDNA inserts (National Institute on Aging) and 4,200 controls, including RNA spikes, housekeeping genes and negative controls. Results At 48 hours, 1 week, 6 and 8 weeks after banding, respectively 779, 537, 1303 and 621 genes were significantly differentially expressed with fold changes ranging from 1.1 till more than 15. The differential genes included hypertrophy markers, like MHC and SERCA2, genes in known hypertrophic processes, like MAPK pathways and genes in calcium-signaling pathways. During the early hypertrophic phase, most genes were up-regulated, while at a later stage genes were mostly down-regulated. Early identified processes involved mainly signalling and transcription related genes, while energy metabolism and cell adhesion were mainly involved at a later stage. Conclusions Using a well-defined array design and data analysis we were able to identify significantly small changes in gene expression for large numbers of genes. Known genes and markers confirmed the hypertrophy process occurring. More extensive study of the data will be presented with new pathways and genes involved in the process of cardiac hypertrophy and may unravel targets for interventions.

Two novel TNNI3 mutations in restrictive cardiomyopathy.
A. van den Wijngaard1, D. Merckx1, C. Marcelis4, E. Rubio1, 2, I. de Coo3, C. de Die1, R. Jongbloed1, H. Smeets1. 1) Clinical Genetics, Academic Hospital Maastricht, Maastricht, Netherlands; 2) Pediatrics, Academic Hospital Maastricht, Maastricht, The Netherlands; 3) Child Neurology, Erasmus MC, Rotterdam, The Netherlands; 4) Clinical Genetics, Radboud Hospital Nijmegen, Nijmegen, The Netherlands. Troponine I (TNNI3) is a sarcomeric protein expressed in the human ventricular myocardium. The protein is essential for the coupling between the myosin heavy chain globulair head and actin during contraction of the cardiac fibers. Occasionally mutations in TNNI3 are found in families with hypertrofic cardiomyopathy (HCM). Recently, also some mutations were reported in patients with restrictive cardiomyopathy. Restrictive cardiomyopathy is a rare cardiomyopathic disorder characterized by impaired ventricular filling with reduced volume, ultimately leading to heart failure. Especially in young children the prognosis is poor compared to adults where the clinical course is more variable. In this study we screened two exons of TNNI3 , known to contain the majority of previously identified mutations, in 69 HCM families for mutations by DHPLC. In addition, the complete TNNI3 gene was analyzed by direct sequence analysis in four families with idiopathic restrictive cardiomyopathy. No mutations were identified in the HCM families. However, in two of the four unrelated probands with restrictive cardiomyopathy we found three mutations. In proband 1 we found a novel splice site mutation (IVS7+2delT) and in proband 2 we found a known mutation (R145Q) together with a novel mutation (Arg192Cys). In both families the probands were young girls (age 0.5 and 9 years respectively). The disease manifestation is more severe in proband 1, which might be explained by the difference in the underlying genetic defect. These data indicates that TNNI3 should be analyzed completely when restrictive cardiomyopathy is diagnosed especially in young patients.

Regional absence of mitochondria causing energy depletion in the failing myocardium of the MLP knockout mouse.
B. Bosch van den1, C. Burg van den1, K. Schoonderwoerd2, P. Lindsey1, H. Scholte2, I. DeCoo2, E. Rooij van1, A. Wijngaard van den3, H. Rockman3, P. Doevendans4, H. Smeets1. 1) Genetics and Cell Biology, University Maastricht, Maastricht, Netherlands; 2) Depts. of Clinical Genetics, Biochemistry and Child Neurology, Erasmus MC Rotterdam, The Netherlands; 3) Dept. of Medicine, Duke University Medical Center, Durham NC; 4) Dept. of Cardiology of the Heart Lung Centre Utrecht (UMCU), The Netherlands. Defects in myocardial mitochondrial structure and function have been associated with heart failure in humans and animal models. However, the exact role for mitochondrial dysfunction in different stages of cardiac disease remains to be elucidated. Mice lacking the muscle LIM protein (MLP) develop morphological and clinical signs resembling human DCM and heart failure. We tested the hypothesis that defects in the cytoskeleton lead to DCM and heart failure through mitochondrial dysfunction in the MLP mouse model. Our results demonstrate a 35% decrease in overall mitochondrial OXPHOS activity and citrate synthase (CS) activity in the failing hearts. However, activity per amount of CS, a measure for mitochondrial density, was normal, indicating a decreased number of mitochondria in the knockouts. Light and electron microscopy revealed regional absence of mitochondria and a decreased overall mitochondrial size. Mitochondrial and nuclear-encoded transcripts were decreased to 60% of the controls, most likely resulting in decreased mitochondrial biogenesis. Peroxisome proliferator activated receptor gamma co-activator 1 (PGC-1 ), a key regulator of this process, was decreased to 67% of the controls and corroborates these findings. MtDNA copy number (ratio mtDNA/nuclear DNA) was slightly increased in the knockouts. Our results show that the absence of MLP causes a local loss of mitochondria, leading to energy depletion. This is likely caused by a disturbed interaction between cytoskeleton and mitochondria, which interferes with energy sensing and energy transfer. Recovery of energy depletion by stimulating mitochondrial biogenesis might be a useful therapeutic strategy for improving the energy imbalance in heart failure.