PMC6409050_01
Heterozygous deletion of exons 5 and 6 in the patient's genomic DNA was detected by the MLPA assay (a). The mother had an identical MLPA result (data not shown). The patient and her mother's genomic DNA produced heterozygous PCR products, suggesting an approximately 2,000-bp deletion (b) (Lane 1: DNA ladder; Lane 2: negative control; Lane 3: patient; Lane 4: patient's mother; and Lane 5: wild-type control).
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fig1
Using this technique, we found that the DNA copy numbers of exons 5 and 6 were half of the other exons in the same SERPING1 gene (Figure 1(a)), suggesting heterozygous deletions for each of these two exons. One pair of these primers (Supplementary Table 1) produced heterozygous PCR products from the patient's genomic DNA (Figure 1(b)).
Genomic DNA sequence electropherograms of the patient and her mother, in comparison with the reference sequence. The deletion is 2,009 bps in size and encompasses exons 5 and 6. The red arrows locate the 3' end breakpoint, whereas the red frame illustrates a part of the deleted sequence. The deletion boundaries are noted on the patient strand, as indicated by the nucleotide positions.
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fig2
Using the gel purification method, the smaller PCR product was then isolated and subjected to Sanger sequencing (Figure 2).
NG_009625.1:g.12156_14164del2009 led to the truncation of a 500-amino acid C1-INH protein into a 252-amino acid dysfunctional protein. Please note the above amino acid sequences relate only to the codons and not the mature protein with post-translational modifications.
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fig3
This large genomic DNA deletion has lost both exons 5 and 6, leading to the truncation of a 500-amino acid protein into a 252-amino acid protein (i.e., a deletion of 272 amino acids and substitution of 24 nonsense amino acids) (Figure 3).