@article {317, title = {Digenic inheritance of an SMCHD1 mutation and an FSHD-permissive D4Z4 allele causes facioscapulohumeral muscular dystrophy type 2.}, journal = {Nat Genet}, volume = {44}, year = {2012}, month = {2012 Dec}, pages = {1370-4}, abstract = {

Facioscapulohumeral dystrophy (FSHD) is characterized by chromatin relaxation of the D4Z4 macrosatellite array on chromosome 4 and expression of the D4Z4-encoded DUX4 gene in skeletal muscle. The more common form, autosomal dominant FSHD1, is caused by contraction of the D4Z4 array, whereas the genetic determinants and inheritance of D4Z4 array contraction-independent FSHD2 are unclear. Here, we show that mutations in SMCHD1 (encoding structural maintenance of chromosomes flexible hinge domain containing 1) on chromosome 18 reduce SMCHD1 protein levels and segregate with genome-wide D4Z4 CpG hypomethylation in human kindreds. FSHD2 occurs in individuals who inherited both the SMCHD1 mutation and a normal-sized D4Z4 array on a chromosome 4 haplotype permissive for DUX4 expression. Reducing SMCHD1 levels in skeletal muscle results in D4Z4 contraction-independent DUX4 expression. Our study identifies SMCHD1 as an epigenetic modifier of the D4Z4 metastable epiallele and as a causal genetic determinant of FSHD2 and possibly other human diseases subject to epigenetic regulation.

}, keywords = {Adult, Aged, Chromosomal Proteins, Non-Histone, Chromosomes, Human, Pair 18, CpG Islands, DNA Methylation, Epigenesis, Genetic, Female, Haplotypes, Heredity, Homeodomain Proteins, Humans, Male, Middle Aged, Muscular Dystrophy, Facioscapulohumeral, Mutation}, issn = {1546-1718}, doi = {10.1038/ng.2454}, author = {Lemmers, Richard J L F and Tawil, Rabi and Petek, Lisa M and Balog, Judit and Block, Gregory J and Santen, Gijs W E and Amell, Amanda M and van der Vliet, Patrick J and Almomani, Rowida and Straasheijm, Kirsten R and Krom, Yvonne D and Klooster, Rinse and Sun, Yu and den Dunnen, Johan T and Helmer, Quinta and Donlin-Smith, Colleen M and Padberg, George W and van Engelen, Baziel G M and de Greef, Jessica C and Aartsma-Rus, Annemieke M and Frants, Rune R and de Visser, Marianne and Desnuelle, Claude and Sacconi, Sabrina and Filippova, Galina N and Bakker, Bert and Bamshad, Michael J and Tapscott, Stephen J and Miller, Daniel G and van der Maarel, Silv{\`e}re M} } @article {322, title = {Facioscapulohumeral muscular dystrophy: consequences of chromatin relaxation.}, journal = {Curr Opin Neurol}, volume = {25}, year = {2012}, month = {2012 Oct}, pages = {614-20}, abstract = {

PURPOSE OF REVIEW: In recent years, we have seen remarkable progress in our understanding of the disease mechanism underlying facioscapulohumeral muscular dystrophy (FSHD). The purpose of this review is to provide a comprehensive overview of our current understanding of the disease mechanism and to discuss the observations supporting the possibility of a developmental defect in this disorder.

RECENT FINDINGS: In the majority of cases, FSHD is caused by contraction of the D4Z4 repeat array (FSHD1). This results in local chromatin relaxation and stable expression of the DUX4 retrogene in skeletal muscle, but only when a polymorphic DUX4 polyadenylation signal is present. In some cases (FSHD2), D4Z4 chromatin relaxation and stable DUX4 expression occur in the absence of D4Z4 array contraction. DUX4 is a germline transcription factor and its expression in skeletal muscle leads to activation of early stem cell and germline programs and transcriptional activation of retroelements.

SUMMARY: Recent studies have provided a plausible disease mechanism for FSHD in which FSHD results from inappropriate expression of the germline transcription factor DUX4. The genes regulated by DUX4 suggest several mechanisms of muscle damage, and provide potential biomarkers and therapeutic targets that should be investigated in future studies.

}, keywords = {Animals, Chromatin, Homeodomain Proteins, Humans, Muscle, Skeletal, Muscular Dystrophy, Facioscapulohumeral, Transcription, Genetic}, issn = {1473-6551}, doi = {10.1097/WCO.0b013e328357f22d}, author = {van der Maarel, Silv{\`e}re M and Miller, Daniel G and Tawil, Rabi and Filippova, Galina N and Tapscott, Stephen J} }