TY - JOUR
T1 - Functional characterization of two novel splicing mutations in the OCA2 gene associated with oculocutaneous albinism type II
AU - Rimoldi, Valeria
AU - Straniero, Letizia
AU - Asselta, Rosanna
AU - Mauri, Lucia
AU - Manfredini, Emanuela
AU - Penco, Silvana
AU - Gesu, Giovanni P.
AU - Del Longo, Alessandra
AU - Piozzi, Elena
AU - Soldà, Giulia
AU - Primignani, Paola
PY - 2014/3/1
Y1 - 2014/3/1
N2 - Oculocutaneous albinism (OCA) is characterized by hypopigmentation of the skin, hair and eye, and by ophthalmologic abnormalities caused by a deficiency in melanin biosynthesis. OCA type II (OCA2) is one of the four commonly-recognized forms of albinism, and is determined by mutation in the OCA2 gene.In the present study, we investigated the molecular basis of OCA2 in two siblings and one unrelated patient. The mutational screening of the OCA2 gene identified two hitherto-unknown putative splicing mutations. The first one (c.1503+5G>A), identified in an Italian proband and her affected sibling, lies in the consensus sequence of the donor splice site of OCA2 intron 14 (IVS14+5G>A), in compound heterozygosity with a frameshift mutation, c.1450_1451insCTGCCCTGACA, which is predicted to determine the premature termination of the polypeptide chain (p.I484Tfs*19). In- silico prediction of the effect of the IVS14+5G>A mutation on splicing showed a score reduction for the mutant splice site and indicated the possible activation of a newly-created deep-intronic acceptor splice site.The second mutation is a synonymous transition (c.2139G>A, p.K713K) involving the last nucleotide of exon 20. This mutation was found in a young African albino patient in compound heterozygosity with a previously-reported OCA2 missense mutation (p.T404M). In- silico analysis predicted that the mutant c.2139G>A allele would result in the abolition of the splice donor site.The effects on splicing of these two novel mutations were investigated using an in- vitro hybrid-minigene approach that led to the demonstration of the causal role of the two mutations and to the identification of aberrant transcript variants.
AB - Oculocutaneous albinism (OCA) is characterized by hypopigmentation of the skin, hair and eye, and by ophthalmologic abnormalities caused by a deficiency in melanin biosynthesis. OCA type II (OCA2) is one of the four commonly-recognized forms of albinism, and is determined by mutation in the OCA2 gene.In the present study, we investigated the molecular basis of OCA2 in two siblings and one unrelated patient. The mutational screening of the OCA2 gene identified two hitherto-unknown putative splicing mutations. The first one (c.1503+5G>A), identified in an Italian proband and her affected sibling, lies in the consensus sequence of the donor splice site of OCA2 intron 14 (IVS14+5G>A), in compound heterozygosity with a frameshift mutation, c.1450_1451insCTGCCCTGACA, which is predicted to determine the premature termination of the polypeptide chain (p.I484Tfs*19). In- silico prediction of the effect of the IVS14+5G>A mutation on splicing showed a score reduction for the mutant splice site and indicated the possible activation of a newly-created deep-intronic acceptor splice site.The second mutation is a synonymous transition (c.2139G>A, p.K713K) involving the last nucleotide of exon 20. This mutation was found in a young African albino patient in compound heterozygosity with a previously-reported OCA2 missense mutation (p.T404M). In- silico analysis predicted that the mutant c.2139G>A allele would result in the abolition of the splice donor site.The effects on splicing of these two novel mutations were investigated using an in- vitro hybrid-minigene approach that led to the demonstration of the causal role of the two mutations and to the identification of aberrant transcript variants.
KW - In vitro analysis
KW - OCA2
KW - Oculocutaneous albinism
KW - Splicing mutations
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U2 - 10.1016/j.gene.2013.11.102
DO - 10.1016/j.gene.2013.11.102
M3 - Article
C2 - 24361966
AN - SCOPUS:84892839018
VL - 537
SP - 79
EP - 84
JO - Gene
JF - Gene
SN - 0378-1119
IS - 1
ER -