Disease for patient 1: Von Willebrand Disease Type1, transmitter VWD-type 3

Disease for patient 2: Von Willebrand Disease Type 3

Patient1: 90 YO female (Afro-Caribbean)

Patient2: 40 YO female (Afro-Caribbean)

Notes multiple variants in the VWF gene but have focused on variants in the D4 domain. However cannot discount the impact of some other variants.

Variant 1: VWF NM_000552.5: c.6647del p.(Cys2216Phefs*9), results in VWF protein missing D4 domain and C-terminal end of molecule

Phenotype patient 1: Reduced VWF levels in VWF:Ag, VWF:ristocetin cofactor, FVIII:C, FVIII(VWF:FVIIIB). Bleeding score 0, required Helixate treatment before and after receiving surgery.

Variant 2: VWF NM_000552.5: c.6432dup p.(Pro2145Thrfs*5)

Three sequence variations in family study showed other variants highlighted p.(Cys1149Arg) and p.(Pro2145Thrfs*5) are not on the same allele.

Does have other variants in VWF but they are stated by authors to not be detrimental. p.(Val510=) is noted to be potentially deleterious.

Phenotype patient 2: severely reduced VWF levels, absence of multimers, bleeding score 32, epistaxis, bruising, oral cavity bleeding, prolonged bleeding from minor wounds, menorrhagia, hemarthrosis, ankle arthropathy.

Suggests premature termination codons in these variants may lead to NMD but that this mechanism was found to be PTC position-dependent. Degradation was not 100% and need to perform cellular experiments.

Disease: Von-willebrand Disorder Type 3

Patient: 26 yo, female

Variant: VWF NM_000552.5 c:997+118 T>G g.(6073501 A>C), homozygous, intronic

Phenotypes: No detectable VWF in plasma, early onset bleeding complications, epistaxis, easy bruising, bleeding following injury, menorrhagia, iron-deficient anemia

Note: underwent prophylaxis replacement therapy, on-demand antihemorrhagic treatments, oral contraceptives, and replacement therapy.

Family: not mentioned

Predictions:

VEP SpliceAI tool predicted variant likely deleterious (delta score 0.95)

Used Polyphen-2 and SIFT which determined pathogenic likelihood.

Neural Network Splicing, Alternative Splice Site Predictor, plug-in MaxEnt(For 5' donor site) of Human Splicing Finder all concur this variant can create a new donor splice site in intron 8. Contains premature stop codon and susceptible to NMD.

Functional work:

qRT-PCR performed to identify levels of VWF in IP-derived endothelial cells.

histochemical immunostaining for IP-derived endothelial cells confirm no VWF production, only a residual amount present. Suggests leaky mutation.

performed RNA sequencing to assess co-regulated gene networks