Plasma thromboplastin antecedent (Factor XI) deficiency in a black family

Area of Science:

• Hematology
• Genetics
• Coagulation Disorders

Background:

• Plasma thromboplastin antecedent (PTA) deficiency, also known as Factor XI deficiency, is a rare inherited bleeding disorder.
• Hageman factor (Factor XII) deficiency is another inherited coagulation disorder, often asymptomatic.
• Understanding the genetic basis and inheritance patterns of these deficiencies is crucial for diagnosis and management.

Observation:

• A Black male presented with a prolonged activated partial thromboplastin time (aPTTT).
• Both clotting assays and immunoassays confirmed a severe deficiency in plasma thromboplastin antecedent (PTA) and suggested homozygous PTA deficiency.
• The proband and two of his children also exhibited reduced Hageman factor (Factor XII) levels, indicative of heterozygous Hageman trait.

Findings:

• This case represents the first documented instance of PTA deficiency in a Black individual.
• The inheritance pattern of PTA deficiency in this family was observed to be independent of Factor VII deficiency.
• Co-occurrence of heterozygous PTA deficiency and heterozygous Hageman trait was noted in offspring.

Implications:

• This case expands the known ethnic diversity of individuals affected by PTA deficiency.
• The independent inheritance of PTA and Hageman factor deficiencies provides insights into their distinct genetic loci.
• Further research is warranted to explore the prevalence and specific genetic factors of coagulation factor deficiencies in diverse populations.