Molecular studies. (A) Sequence electropherogram of proband’s (III-1) genomic DNA, showing the c.263-10A > G heterozygous substitution. (B) PCR-RFLP analysis of the c.263-10A > G mutation in affected family members available. DraI endonuclease cuts wild type DNA molecules, leaving mutated alleles uncut. (C) Sequence electropherograms of RT-PCR amplicons encompassing exon 5 and 7. Analysis of proband’s cDNA suggest the coexistence of normal and altered CCM1 transcripts. (D) Direct sequencing of clones obtained from RT-PCR reactions revealed the partial retention of intron 5 within CCM1 transcript as a consequence of the abnormal acceptor splice site created by c.263-10A > G mutation at genomic level.