SNP Shot: Genomic Insights

Von Willebrand disease (VWD) is a bleeding disorder that impairs blood clotting, leading to extended bleeding after an injury. Common symptoms include easy bruising, prolonged nosebleeds, and excessive bleeding or oozing following injuries, surgeries, or dental procedures. In milder cases, abnormal bleeding after surgery or significant injury may be the first indication of VWD. Women with VWD may experience heavy or prolonged menstrual bleeding (menorrhagia) and, in some instances, bleeding in the reproductive tract during pregnancy and childbirth. Severe VWD can manifest as significant bleeding even from minor injuries or spontaneously, without any apparent cause. The symptoms of VWD can fluctuate over time. Factors such as age, pregnancy, exercise, and stress can influence the frequency of bleeding episodes.

VWD is classified into three primary types. Type 1 includes a subtype (1C), while type 2 is further divided into four subtypes (2A, 2B, 2M, and 2N). Type 1 is the most prevalent, affecting approximately 75% of individuals with VWD. While generally mild, some individuals with Type 1 may experience severe symptoms. Type 2 accounts for around 15% of cases and typically presents with intermediate severity. Type 3 is the rarest and usually the most severe form, representing about 5% of cases.

Acquired von Willebrand syndrome, another form of the disorder, arises not from inherited genetic mutations but is typically associated with other underlying conditions, such as diseases affecting bone marrow or immune cell function. This rare syndrome is characterized by abnormal bleeding into the skin and soft tissues, usually beginning in adulthood.

Inheritance:

VWD can be inherited in different ways. The majority of Type 1 and Type 2 VWD cases follow an autosomal dominant inheritance pattern. This means that having only one copy of the altered gene in each cell is enough to cause the disorder.

Type 3, some Type 2 cases, and a small percentage of Type 1 cases are inherited in an autosomal recessive pattern. This requires both copies of the gene in each cell to carry a variant for the disorder to manifest. In autosomal recessive inheritance, each parent of an affected individual carries one copy of the altered gene but usually does not exhibit signs or symptoms of the condition themselves.