Myoclonus-dystonia due to maternal uniparental disomy.
BACKGROUND
Myoclonus-dystonia is a movement disorder often associated with mutations in the maternally imprinted epsilon-sarcoglycan (SGCE) gene located on chromosome 7q21. Silver-Russell syndrome is a heterogeneous disorder characterized by prenatal and postnatal growth restriction and a characteristic facies, caused in some cases by maternal uniparental disomy of chromosome 7.


OBJECTIVE
To describe and investigate the combination of a typical myoclonus-dystonia syndrome and Silver-Russell syndrome.


METHODS
Clinical and neurophysiological examination as well as cytogenetic and molecular analyses.


METHODS
Movement disorder clinic. Patient A 36-year-old man with typical myoclonus-dystonia and Silver-Russell syndrome.


METHODS
Clinical description of the disease and its genetic cause.


RESULTS
Cytogenetic analysis revealed mosaicism for a small chromosome 7 marker chromosome. Microsatellite analysis indicated loss of the paternal allele and maternal uniparental disomy of chromosome 7. In keeping with the maternal imprinting mechanism, no unmethylated allele of SGCE was detected after bisulfite treatment of the patient's DNA, and reverse transcription-polymerase chain reaction demonstrated loss of SGCE expression. Molecular analysis ruled out mutations in the SGCE gene.


CONCLUSIONS
We identified a new genetic alteration-maternal chromosome 7 disomy-that can cause myoclonus-dystonia. This alteration results in repression of both alleles of the maternally imprinted SGCE gene and suggests SGCE loss of function as the disease mechanism.
Service de Neurologie, Hôpital Saint-Antoine, AP-HP, Paris, France.
Emilie
E
Guettard
Marie-France
MF
Portnoi
Katja
K
Lohmann-Hedrich
Boris
B
Keren
Sylvie
S
Rossignol
Susen
S
Winkler
Imen
I
El Kamel
Smaranda
S
Leu
Emmanuelle
E
Apartis
Marie
M
Vidailhet
Christine
C
Klein
Emmanuel
E
Roze
D000328:Adult; D002897:Chromosomes, Human, Pair 7 / Q000235:genetics*; D004252:DNA Mutational Analysis; D020821:Dystonic Disorders / Q000235:genetics* / Q000503:physiopathology; D005819:Genetic Markers / Q000235:genetics; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D018392:Genomic Imprinting / Q000235:genetics; D006801:Humans; D040582:Inheritance Patterns / Q000235:genetics; D019656:Loss of Heterozygosity / Q000235:genetics; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D009207:Myoclonus / Q000235:genetics* / Q000503:physiopathology; D049031:Sarcoglycans / Q000235:genetics*; D013577:Syndrome; D024182:Uniparental Disomy / Q000175:diagnosis / Q000235:genetics*
D005819:Genetic Markers; C526572:SGCE protein, human; D049031:Sarcoglycans