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

Disease: Von Willebrand Disease (VWD) Type 2A

Patient: 31 yo, Female

Variant1: VWF NC_000012.12: c.875-5T>Gdel, p.(Ser292_Glu333delinsLys) Causes complete exon 8 skipping

Variant2: VWF NM_000552.5: c.813C>G, p.(Tyr271*)

Phenotypes: History of bleeding (epistaxis, uncontrollable by conventional hemostatic treatment), Easy bruising, gum bleeding, excessive menstrual bleeding, mild decrease in plasma VWF:Ag, severe impairment in VWF function, VWF:Ab/VWF:Ag ratio decreased, VWF:CB/VWF:Ag ratio decreased, FVIII:C lvs slighly below normal range

Family: Son had bleeding diathesis and spontaneous epistaxis (less severe than proband), normal parents

In silico data available: SpliceAI delta score of 0.51 for loss of splice acceptor caused by variant 1

Alamut showed small to moderate effects of the variant on normal splicing of VWF

NetGene2 showed weak strength of 3' splice sites in exon 8

SpliceAid2 showed TIA-1 and TIAL 1, which bind to U-rich motifs and facilitate 5' splice site recognition where destroyed in the mutated sequence