Fig. 2

cDNA amplification and sequencing of fragments encompassing the putative POLR3B exonic deletions. a Patient 1: RNA isolation was performed using standard method and followed by reverse transcription-polymerase chain reaction (RT-PCR). Amplification of the fragment of complement DNA (cDNA) encompassing exons 20 to 23 revealed the presence of a putative deletion. The sequence in the overlapping reading frame were showing a normal cDNA PCR product of 630 bp, covering exons 20 to 23. The second sequence of a reduced product of 353 bp was encompassing exons 20 to 23, suggesting the complete or partial deletion of exons 21 and 22. b Patient 2: RNA isolation was performed using standard method and followed by reverse transcription-polymerase chain reaction (RT-PCR). Amplification of the fragment of complement DNA (cDNA) encompassing the exon 25 to 28 revealed the presence of a putative deletion. The sequence in the overlapping reading frame were showing a normal cDNA PCR product of 634 bp, covering exons 25 to 28. The second sequence of a reduced product of 346 bp was encompassing exons 25 and 28, suggesting the complete or partial deletion of exons 26 and 27. c Scheme depicts the large deletions in POLR3B gene characterized in our index patients with classical clinical and radiological findings of 4H