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Molecular basis of very long chain acyl‐CoA dehydrogenase deficiency in three Israeli patients: Identification of a complex mutant allele with P65L and K247Q mutations, the former being an exonic mutation causing exon 3 skipping
Author(s) -
Watanabe Hiroh,
Orii Kenji E.,
Fukao Toshiyuki,
Song XiangQian,
Aoyama Toshifumi,
IJlst Lodewijk,
Ruiter Jos,
Wanders Ronald J.A.,
Kondo Naomi
Publication year - 2000
Publication title -
human mutation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 162
eISSN - 1098-1004
pISSN - 1059-7794
DOI - 10.1002/(sici)1098-1004(200005)15:5<430::aid-humu4>3.0.co;2-1
Subject(s) - biology , frameshift mutation , nonsense mutation , exon , mutation , transition (genetics) , genetics , microbiology and biotechnology , transversion , mutant , intron , compound heterozygosity , acyl coa dehydrogenase , allele , gene , biochemistry , enzyme , dehydrogenase , missense mutation
Abstract Very long chain acyl‐CoA dehydrogenase (VLCAD) deficiency is a life‐threatening disorder of mitochondrial fatty acid β‐oxidation. We identified four novel mutations in three unrelated patients. All patients had the severe childhood form of VLCAD deficiency with early onset and high mortality. Immunoblot analysis revealed that VLCAD protein was undetectable in patients 2 and 3, whereas normal‐size VLCAD protein and an aberrant form of VLCAD (4kDa smaller) were detected in patient 1. As expected, null mutations were found in patients 2 and 3: patient 2 is homozygous for a frameshift mutation, del 4 bp at 798‐801, and patient 3 is homozygous for a nonsense mutation 65C>A(S22X). Patient 1 was homozygous for a complex mutant allele containing two alterations, including a 194C>T transition (P65L) and 739A>C transversion (K247Q); in the case of P65L, the amino acid change does not reduce enzyme activity. However, the nucleotide change resulted in exon 3 skipping, whereas the latter K247Q mutation had a drastic effect on enzyme activity. We verified these events by in vivo splicing experiments and transient expression analysis of mutant cDNAs. The P65L mutation locates 11 bases upstream of a splice donor site of intron 3. This is an example of an exonic mutation which affects exon‐splicing. Hum Mutat 15:430–438, 2000. © 2000 Wiley‐Liss, Inc.