Papers by Marc Abramowicz
The European respiratory journal, Sep 1, 2003
Primary pulmonary hypertension (PPH) is characterised by sustained elevations of pulmonary arteri... more Primary pulmonary hypertension (PPH) is characterised by sustained elevations of pulmonary arterial pressure without a demonstrable cause, leading to right ventricular failure and death. Hereditary mutations in the bone morphogenetic protein receptor type II (BMPR2) gene result in familial PPH transmitted as an autosomal dominant trait, albeit with low penetrance. The causes in cases without a BMPR2 mutation are unknown, but a syndrome of pulmonary arterial hypertension (PAH) similar to hereditary PPH is associated with systemic connective tissue disease, congenital heart disease, portal hypertension, and human immunodeficiency virus infection, or with the use of appetite-suppressant drugs. The authors identified a BMPR2 gene mutation in a 27-yr-old female who developed PAH after a short course of the appetite-suppressant drug amfepramone (diethylpropion). This allowed molecular genetic counselling and prevention of potentially harmful drug exposure in the patient9s son treated for attention deficit disorder with methylphenidate, an amphetamine-related drug. No BMPR2 mutation was found in four additional, unrelated patients with appetite suppressant-related PPH. The findings provide strong evidence that amfepramone can trigger primary pulmonary hypertension in a bone morphogenetic protein receptor type II gene mutation carrier, and indicate that other genes are probably implicated in genetic susceptibility to appetite suppressants.
bioRxiv (Cold Spring Harbor Laboratory), Feb 23, 2023
BMC Nephrology, Aug 28, 2014
Human Genomics
Background Congenital hydrocephalus is characterized by ventriculomegaly, defined as a dilatation... more Background Congenital hydrocephalus is characterized by ventriculomegaly, defined as a dilatation of cerebral ventricles, and thought to be due to impaired cerebrospinal fluid (CSF) homeostasis. Primary congenital hydrocephalus is a subset of cases with prenatal onset and absence of another primary cause, e.g., brain hemorrhage. Published series report a Mendelian cause in only a minority of cases. In this study, we analyzed exome data of PCH patients in search of novel causal genes and addressed the possibility of an underlying oligogenic mode of inheritance for PCH. Materials and methods We sequenced the exome in 28 unrelated probands with PCH, 12 of whom from families with at least two affected siblings and 9 of whom consanguineous, thereby increasing the contribution of genetic causes. Patient exome data were first analyzed for rare (MAF < 0.005) transmitted or de novo variants. Population stratification of unrelated PCH patients and controls was determined by principle compo...
Clinical Genetics
Bi‐allelic variants affecting one of the four genes encoding the AP4 subunits are responsible for... more Bi‐allelic variants affecting one of the four genes encoding the AP4 subunits are responsible for the “AP4 deficiency syndrome.” Core features include hypotonia that progresses to hypertonia and spastic paraplegia, intellectual disability, postnatal microcephaly, epilepsy, and neuroimaging features. Namely, AP4M1 (SPG50) is involved in autosomal recessive spastic paraplegia 50 (MIM#612936). We report on three patients with core features from three unrelated consanguineous families originating from the Middle East. Exome sequencing identified the same homozygous nonsense variant: NM_004722.4(AP4M1):c.1012C>T p.Arg338* (rs146262009). So far, four patients from three other families carrying this homozygous variant have been reported worldwide. We describe their phenotype and compare it to the phenotype of patients with other variants in AP4M1. We construct a shared single‐nucleotide polymorphism (SNP) haplotype around AP4M1 in four families and suggest a probable founder effect of A...
Revue Médicale de Bruxelles, 2002
Created in 1987, the department of medical genetics finds its origins in molecular endocrinology ... more Created in 1987, the department of medical genetics finds its origins in molecular endocrinology research which had developed from the seventies at the Institut de Recherche Interdisciplinaire en Biologie Humaine et Moleculaire (IRIBHM) of the Faculty of Medicine. After its fusion with the Center of Human Genetics of the ULB, in 1992, the department is composed of three units: the lab of molecular genetics and oncology, the lab of cytogenetics and a clinical genetics unit. One thousand consultations of genetic counseling and more than 15,000 molecular or cytogenetic diagnostic procedures are performed annually. The development of the clinical activities was paralleled by a very active research activity, resulting in a series of "firsts". Amongst the main results are: the identification of the first mutations responsible for congenital hypothyroidism; the molecular cloning of the TSH receptor and of a series of "orphan" G protein-coupled receptors; the identificat...
Gastroenterology, Jun 1, 2018
A few rare monogenic primary immunodeficiencies (PIDs) are characterized by chronic intestinal in... more A few rare monogenic primary immunodeficiencies (PIDs) are characterized by chronic intestinal inflammation that resembles Crohn's disease (CD). We investigated whether 23 genes associated with 10 of these monogenic disorders contain common, low-frequency, or rare variants that increase risk for CD. Common and low frequency variants in 1 Mb loci centered on the candidate genes were analyzed using meta-data corresponding to genotypes of approximately 17,000 patients with CD or without CD (controls) in Europe. The contribution of rare variants was assessed by high-throughput sequencing of 4750 individuals, including 660 early-onset and/or familial cases among the 2390 patients with CD. Variants were expressed from vectors in SW480 or HeLa cells and functions of their products were analyzed in immunofluorescence, luciferase, immunoprecipitation, and immunoblot assays. We reproduced the association of the interleukin 10 locus with CD (P = .007), although none of the significantly as...
Genes, Aug 20, 2021
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Ophthalmic Genetics, 2022
Background: The c.2299delG mutation is prevalent and accounts for 24.5% USH2A pathogenic variants... more Background: The c.2299delG mutation is prevalent and accounts for 24.5% USH2A pathogenic variants, with promising prospects for customized gene therapy. Materials and Methods: We compared the ocular and auditory phenotypes in a retrospective cohort of 169 Usher type 2 patients, with and without the c.2299delG allele, including visual acuity, slit-lamp examination, optical coherence tomography, kinetic perimetry, and audiometric assessment to define the hearing disability. Statistical methods used were covariate balancing propensity score and adjusted survival curves log-rank test for the analysis of visual acuity. Results: We compare 54 Usher patients (31%) carrying at least one c.2299delG allele to 109 patients without this variant. The mean ages at onset of night blindness (14 years) and onset of peripheral vision deficiency (24 years) were similar in both groups, as was the severity of hearing loss (p = 0.731), even in homozygotes (p = 0.136). Based on the covariate balancing propensity score, the c.2299delG carrier patients developed cataract and reached a BCVA of 20/63 earlier than patients without this mutation (mean age 36 versus 42 y.o.; and 52.2 versus 55.1 y.o., respectively). Using adjusted survival curves and a log-rank test based on inverse probability weighting, patients with the c.2299delG variant reach blindness (BCVA <20/400) at 42.3 years old instead of 79.8 years for other USH2A pathogenic variants. Conclusions: We conclude that c.2299delG is associated with a more severe phenotype of the Usher type 2, in homozygotes and in compound heterozygotes.
Frontiers in Immunology, 2021
Graft-versus-host disease (GVHD) remains a major clinical drawback of allogeneic hematopoietic st... more Graft-versus-host disease (GVHD) remains a major clinical drawback of allogeneic hematopoietic stem cell transplantation (HSCT). Here, we investigated how the stress responsive heme catabolizing enzyme heme oxygenase-1 (HO-1, encoded by HMOX1) regulates GVHD in response to allogeneic hematopoietic stem cell transplantation in mice and humans. We found that deletion of the Hmox1 allele, specifically in the myeloid compartment of mouse donor bone marrow, promotes the development of aggressive GVHD after allogeneic transplantation. The mechanism driving GVHD in mice transplanted with allogeneic bone marrow lacking HO-1 expression in the myeloid compartment involves enhanced T cell alloreactivity. The clinical relevance of these observations was validated in two independent cohorts of HSCT patients. Individuals transplanted with hematopoietic stem cells from donors carrying a long homozygous (GT)n repeat polymorphism (L/L) in the HMOX1 promoter, which is associated with lower HO-1 expre...
Revue Médicale de Bruxelles, 2001
Genetic counseling is a medical act that consists of informing a patient of his/her risk of devel... more Genetic counseling is a medical act that consists of informing a patient of his/her risk of developing a genetic disorder, or of transmitting it to his/her offspring, and of informing about diagnostic and therapeutic options, allowing for informed choices. When about a risk to future offspring, genetic counseling is often linked to prenatal diagnosis with elective termination of affected pregnancies, or in selected cases, to pre-implatation sorting of embryos ("pre-implantation diagnosis"). In a growing number of indications regarding late-onst hereditary disorders, like Huntington's chorea or some hereditary cancers, genetic counseling aims at optimizing medical prevention, or at allowing patients to make life choices which they deem appropriate. The coming years will witness the blossoming of tests allowing for medical previsions based on the genome ("predictive medicine") in frequent, multigenic disorders, or allowing to target drug therapies to the bioche...
American Journal of Transplantation, 2018
Hernandez et al recently reported on several large genomewide association studies (GWAS) in kidne... more Hernandez et al recently reported on several large genomewide association studies (GWAS) in kidney transplantation. 1 In particular, they investigated the effect of either donor single nucleotide polymorphisms (SNPs), recipient SNPs, or combined donor-recipient SNPs on graft survival and acute rejection. Despite impressive patient numbers, no SNP signal emerged. The authors concluded that "both phenotype heterogeneity and sample size may have contributed." We sought to understand the lack O RCI D
European Journal of Human Genetics, 2019
Intellectual disability (ID), megalencephaly, frontal predominant pachygyria, and seizures, previ... more Intellectual disability (ID), megalencephaly, frontal predominant pachygyria, and seizures, previously called "thin" lissencephaly, are reported to be caused by recessive variants in CRADD. Among five families of different ethnicities identified, one homozygous missense variant, c.509G>A p.(Arg170His), was of Finnish ancestry. Here we report on the phenotypic variability associated for this potential CRADD founder variant in 22 Finnish individuals. Exome sequencing was used to identify candidate genes in Finnish patients presenting with ID. Targeted Sanger sequencing and restriction enzyme analysis were applied to screen for the c.509G>A CRADD variant in cohorts from Finland. Detailed phenotyping and genealogical studies were performed. Twenty two patients were identified with the c.509G>A p.(Arg170His) homozygous variant in CRADD. The majority of the ancestors originated from Northeastern Finland indicating a founder effect. The hallmark of the disease is frontotemporal predominant pachygyria with mild cortical thickening. All patients show ID of variable severity. Aggressive behavior was found in nearly half of the patients, EEG abnormalities in five patients and megalencephaly in three patients. This study provides detailed data about the phenotypic spectrum of patients with lissencephaly due to a CRADD variant that affects function. High inter-and intrafamilial phenotypic heterogeneity was identified in patients with pachygyria caused by the homozygous CRADD founder variant. The phenotype variability suggests that additional genetic and/or environmental factors play a role in the clinical presentation. Since frontotemporal pachygyria is the hallmark of the disease, brain imaging studies are essential to support the molecular diagnosis for individuals with ID and a CRADD variant.
Revue médicale de Bruxelles
Molecular biology has produced important achievements in research, and provides useful applicatio... more Molecular biology has produced important achievements in research, and provides useful applications to the clinical field. This is true today in diagnostics, and will be true in therapeutics tomorrow. The identification of pathogenic mutations through direct analysis of known genes allows diagnoses to be reached in a growing number of disorders. When mutations cannot be identified, familial linkage studies using polymorphic molecular markers will reach a diagnosis indirectly, most of the times. This is useful either presymptomatically or prenatally. The identification of genetic risk factors in targeted populations is becoming a means of prevention of multifactorial diseases. This approach opens a very large field of applications of molecular genetics in clinical practice. Basic concepts of molecular genetics are briefly reviewed, and the principles of diagnostics in hereditary diseases are approached via a few representative examples.
Transplantation Journal, 2012
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Papers by Marc Abramowicz