Gene conversion events in adult-onset spinal muscular atrophy.
OBJECTIVE
To investigate the possible occurrence of a conversion event in three patients with adult-onset spinal muscular atrophy (SMA) type IV, which represents the mildest form within the spectrum of the SMA phenotype.


METHODS
We observed three patients with adult onset SMA and apparent isolated deletion of telomeric survival motor neuron (SMN1) exon 7. To distinguish between a deletion and a sequence conversion event of exon 7, these patients were analyzed in greater detail by a simple PCR-based assay.


RESULTS
Analysis by DdeI digestion showed products for both telomeric and centromeric copies of exon 8. These findings indicated a gene conversion event as the site for primer R111 was retained at least in one of two alleles.


CONCLUSIONS
These results provide first evidence that a conversion event may be also associated with adult-onset SMA, and further support the notion that a gene conversion event is usually associated with a milder SMA phenotype and a later onset of disease.
Mazzei
R
R
Institutes of Neurological Sciences, National Research Council, Piano Lago di Mangone, Cosenza, Italy.
Gambardella
A
A
Conforti
F L
FL
Magariello
A
A
Patitucci
A
A
Gabriele
A L
AL
Sprovieri
T
T
Labate
A
A
Valentino
P
P
Bono
F
F
Bonavita
S
S
Zappia
M
M
Muglia
M
M
Quattrone
A
A
D000328:Adult; D017668:Age of Onset; D000368:Aged; D017362:Cyclic AMP Response Element-Binding Protein; D005091:Exons; D017353:Gene Deletion; D006801:Humans; D008297:Male; D009134:Muscular Atrophy, Spinal / Q000235:genetics* / Q000473:pathology; D009419:Nerve Tissue Proteins / Q000235:genetics*; D010641:Phenotype; D016133:Polymerase Chain Reaction; D016601:RNA-Binding Proteins; D055532:SMN Complex Proteins; D012720:Severity of Illness Index; D055533:Survival of Motor Neuron 1 Protein; D016615:Telomere / Q000235:genetics
D017362:Cyclic AMP Response Element-Binding Protein; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins; D055532:SMN Complex Proteins; C526471:SMN1 protein, human; D055533:Survival of Motor Neuron 1 Protein