TY - JOUR
T1 - Targeted re-sequencing of F8, F9 and VWF
T2 - characterization of Ion Torrent data and clinical implications for mutation screening.
AU - Manderstedt, Eric
AU - Nilsson, Rosanna
AU - Lind-Halldén, Christina
AU - Ljung, Rolf
AU - Astermark, Jan
AU - Halldén, Christer
PY - 2019
Y1 - 2019
N2 - Mutations are not identified in ~5% of hemophilia A and 10-35% of type 1 VWD patients. The bleeding tendency also varies among patients carrying the same causative mutation, potentially indicating variants in additional genes modifying the phenotype that cannot be identified by routine single-gene analysis. The F8, F9 and VWF genes were analyzed in parallel using an AmpliSeq strategy and Ion Torrent sequencing. Targeting all exonic positions showed an average read depth of >2000X and coverage close to 100% in 24 male patients with known disease-causing mutations. Discrimination between reference alleles and alternative/indel alleles was adequate at a 25% frequency threshold. In F8, F9 and VWF there was an absolute majority of all reference alleles at allele frequencies >95% and the average alternative allele and indel frequencies never reached above 10% and 15%, respectively. In VWF, 4-5 regions showed lower reference allele frequencies; in two regions covered by the pseudogene close to the 25% cut-off for reference alleles. All known mutations, including indels, gross deletions and substitutions, were identified. Additional VWF variants were identified in three hemophilia patients. The presence of additional mutations in 2 out of 16 (12%) randomly selected hemophilia patients indicates a potential mutational contribution that may affect the disease phenotype and counseling in these patients. Parallel identification of disease-causing mutations in all three genes not only confirms the deficiency, but differentiates phenotypic overlaps and allows for correct genetic counseling.
AB - Mutations are not identified in ~5% of hemophilia A and 10-35% of type 1 VWD patients. The bleeding tendency also varies among patients carrying the same causative mutation, potentially indicating variants in additional genes modifying the phenotype that cannot be identified by routine single-gene analysis. The F8, F9 and VWF genes were analyzed in parallel using an AmpliSeq strategy and Ion Torrent sequencing. Targeting all exonic positions showed an average read depth of >2000X and coverage close to 100% in 24 male patients with known disease-causing mutations. Discrimination between reference alleles and alternative/indel alleles was adequate at a 25% frequency threshold. In F8, F9 and VWF there was an absolute majority of all reference alleles at allele frequencies >95% and the average alternative allele and indel frequencies never reached above 10% and 15%, respectively. In VWF, 4-5 regions showed lower reference allele frequencies; in two regions covered by the pseudogene close to the 25% cut-off for reference alleles. All known mutations, including indels, gross deletions and substitutions, were identified. Additional VWF variants were identified in three hemophilia patients. The presence of additional mutations in 2 out of 16 (12%) randomly selected hemophilia patients indicates a potential mutational contribution that may affect the disease phenotype and counseling in these patients. Parallel identification of disease-causing mutations in all three genes not only confirms the deficiency, but differentiates phenotypic overlaps and allows for correct genetic counseling.
U2 - 10.1371/journal.pone.0216179
DO - 10.1371/journal.pone.0216179
M3 - Article
SN - 1932-6203
VL - 14
JO - PLoS ONE
JF - PLoS ONE
IS - 4
ER -