INVESTIGADORES
CASALE Cesar Horacio
artículos
Título:
A two bases deletion in the exon 6 of the 3-hydroxy-3-methylglutaryl coenzime A lyase (HL) gene produce the skiping of exon 5 and 6 determines 3-hydroxy-3-methylglutaric aciduria
Autor/es:
CASALS N; PIE J; CASALE CH; ZAPATER N; RIBES, A.; CASTRO-GAGO, M.; RODRIGUEZ-SEGADE S; WANDERS R. J. A.; HEGARDT FG
Revista:
JLR PAPERS IN PRESS
Referencias:
Año: 1997 vol. 38 p. 2303 - 2313
ISSN:
0022-2275
Resumen:
A novel two-base deletion in the 3-hydroxy-3-methylglutaar>
llc oenzyme A lyase (HL) gene was found in a Spanish
patient with homozygous 3-hydroxy-3-methylglutaric aciduria.
Amplification by RT-PCR of the mRNAs showed that the
gene was transcribed into three different As. One
showed the complete deletion of exons 5 and 6 located between
nucleotides 348 and 561 of the HL cDNA. The second
transcript showed deletion of exon 6 only, and the third contained
a two-base deletion CT in exon 6, corresponding to
nucletotides 504 and 505 of the HL cDNA. These aberrant
mRNAs are predicted to encode three abnormal HMG-CoA
lyase proteins; the first (from skipped exons 5 and 6) lacks 71
amino acids, which represents 24% of the mature protein; the
second, (from the skipping of exon 6, producing a frameshift)
contains only 192 amino acids, the last 26 of which are missense
amino acids preceding a stop codon; the third contains
only 175 amino acids, the last 7 of which are missense. Northern
blot analysis showed that the HL mRNA levels of the patient
were 4% of the control. PCR quantitative analysis indicated
that the mRNA lacking exons 5 and 6 was the most
abundant, representing 88% of the total. The other two
mRNAs represented 8% and 4%, respectively. In the genomic
DNA only one CT deletion was found at positions +7 and +8
at beginning of exon 6. No mutations were observed in the
splice donor, splice acceptor, or pyrimidine-rich sequences of
the intronic regions flanking exons 5 and 6. All three aberrant
mRNAs resulted only from the deletion of nucleotides CT.I
We suggest that this deletion may affect the interaction between
the small nuclear ribonucleoproteins (snRNPs) and
exon 6, and that, as a result, the abnormal splicing of the premRNA
produces two different aberrant transcripts.-