The molecular lesion is in Dnaaf1 (NM_026648) at chr8:119582732 bp (exon 4: c.556 + 2T - C). This is in the splice donor site of exon 4, two bases distal from the exon. This results in splicing mutations, with both skipping of exon 4 and retention of intron 4 seen in RT-PCR analysis. Either splicing mutation will result in premature truncation of the encoded protein. (J:199782, J:240195)