A novel donor splice site characterized by CFTR mRNA analysis induces a new pseudo-exon in CF patients.
BACKGROUND
The CFTR gene is tightly regulated and differentially expressed in many mucosal epithelial cell types. There is evidence of an increasing number of genomic variations in the intronic regions influencing mRNA splicing, and also the level of normal CFTR transcript.


METHODS
In the present study, we investigate the molecular defect by RT-PCR analyzing the mRNA of 25 cystic fibrosis (CF) patients in whom only one or no CF allele had been identified after DNA analysis (of all the exons of the CFTR gene).


RESULTS
mRNA analysis led to the detection of a cryptic exon in two patients: the new exon is a 104 bp insertion between exons 10 and 11 and is caused by a new point mutation c.1584+18672 bp A>G (http://www.hgvs.org/mutnomen/) discovered in intron 10; moreover, they showed the absence of exon 9 skipping.


CONCLUSIONS
Our results confirm the utility of RNA analysis in discovering new mutations and in investigating their effect on normal splicing processes.
Costantino
Lucy
L
Medical Genetics Laboratory, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Via Commenda, 12, 20122 Milan, Italy.
Claut
Laura
L
Paracchini
Valentina
V
Coviello
Domenico A
DA
Colombo
Carla
C
Porcaro
Luigi
L
Capasso
Patrizia
P
Zanardelli
Maddalena
M
Pizzamiglio
Giovanna
G
Degiorgio
Dario
D
Seia
Manuela
M
D019943:Amino Acid Substitution; D001483:Base Sequence; D003550:Cystic Fibrosis / Q000235:genetics*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics*; D005091:Exons / Q000235:genetics*; D006801:Humans; D007438:Introns / Q000235:genetics; D008969:Molecular Sequence Data; D017354:Point Mutation; D022821:RNA Splice Sites / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
C505032:CFTR protein, human; D022821:RNA Splice Sites; D012333:RNA, Messenger; D019005:Cystic Fibrosis Transmembrane Conductance Regulator