Identification of a candidate modifying gene for spinal muscular atrophy by comparative genomics.
Spinal muscular atrophy (SMA) is a common recessive disorder characterized by the loss of lower motor neurons in the spinal cord. The disease has been classified into three types based on age of onset and severity. SMA I-III all map to chromosome 5q13 (refs 2,3), and nearly all patients display deletions or gene conversions of the survival motor neuron (SMN1) gene. Some correlation has been established between SMN protein levels and disease course; nevertheless, the genetic basis for SMA phenotypic variability remains unclear, and it has been postulated that the loss of an additional modifying factor contributes to the severity of type I SMA. Using comparative genomics to screen for such a factor among evolutionarily conserved sequences between mouse and human, we have identified a novel transcript, H4F5, which lies closer to SMN1 than any previously identified gene in the region. A multi-copy microsatellite marker that is deleted in more than 90% of type I SMA chromosomes is embedded in an intron of this gene, indicating that H4F5 is also highly deleted in type I SMA chromosomes, and thus is a candidate phenotypic modifier for SMA.
Scharf
J M
JM
Program in Neuroscience, Harvard Medical School, Boston, Massachusetts 02115, USA.
Endrizzi
M G
MG
Wetter
A
A
Huang
S
S
Thompson
T G
TG
Zerres
K
K
Dietrich
W F
WF
Wirth
B
B
Kunkel
L M
LM
D000595:Amino Acid Sequence; D000818:Animals; D002874:Chromosome Mapping; D002895:Chromosomes, Human, Pair 5; D003001:Cloning, Molecular; D017362:Cyclic AMP Response Element-Binding Protein; D017353:Gene Deletion; D005819:Genetic Markers; D006720:Homozygote; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009134:Muscular Atrophy, Spinal / Q000235:genetics*; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D016601:RNA-Binding Proteins; D055532:SMN Complex Proteins; D017386:Sequence Homology, Amino Acid; D055533:Survival of Motor Neuron 1 Protein
D017362:Cyclic AMP Response Element-Binding Protein; D005819:Genetic Markers; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins; C114841:SERF1A protein, human; D055532:SMN Complex Proteins; C526471:SMN1 protein, human; C526472:Smn1 protein, mouse; D055533:Survival of Motor Neuron 1 Protein