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Hybrid survival motor neuron genes in Japanese patients with spinal muscular atrophy
Author(s) -
Nishio H.,
Horikawa H.,
Yakura H.,
Sugie K.,
Nakamuro T.,
Koterazawa K.,
Ishikawa Y.,
Lee M. J.,
Wada H.,
Takeshima Y.,
Matsuo M.,
Sumino K.
Publication year - 1999
Publication title -
acta neurologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.967
H-Index - 95
eISSN - 1600-0404
pISSN - 0001-6314
DOI - 10.1111/j.1600-0404.1999.tb07367.x
Subject(s) - spinal muscular atrophy , sma* , exon , motor neuron , biology , genetics , gene , pathology , medicine , disease , mathematics , combinatorics
Spinal muscular atrophy (SMA) is a frequently occurring autosomal recessive disease, characterized by the degeneration of spinal cord anterior horn cells, leading to muscular atrophy. Most SMA patients carry homozygous deletions of the telomeric survival motor neuron gene (SMN) exons 7 and 8. In the study presented here, we examined 20 Japanese SMA patients and found that 4 of these patients were lacking in telomeric SMN exon 7, but retained exon 8. In these 4 patients, who exhibited all grades of disease severity, direct sequencing analysis demonstrated the presence of a hybrid SMN gene in which centromeric SMN exon 7 was adjacent to telomeric SMN exon 8. In an SMA family, a combination of polymerase chain reaction and enzyme‐digestion analysis and haplotype analysis with the polymorphic multicopy marker Ag1‐CA indicated that the patient inherited the hybrid gene from her father. In conclusion, hybrid SMN genes can be present in all grades of disease severity and inherited from generation to generation in an SMA family.