A 6-year-old boy presents to the emergency department with spontaneous hemarthrosis of the left knee and ecchymoses on his arms and legs following minor trauma 2 days ago. His mother reports similar bleeding episodes in her brother during childhood that resolved by adolescence. Physical examination reveals joint swelling and warmth. Laboratory studies show: Platelet count: 245,000/μL PT: 12 seconds (normal) aPTT: 68 seconds (normal: 25-35 seconds) Thrombin time: 14 seconds (normal) Factor VIII activity: 6% (normal: 80-100%) Factor IX activity: 95% (normal) Which of the following best explains the inheritance pattern of this patient's underlying coagulation disorder?
- A)Autosomal dominant with variable expressivity
- B)Autosomal recessive requiring two mutant alleles for disease manifestation
- C)X-linked recessive affecting males who inherit a single mutant allele from carrier mothersGABARITO
- D)Mitochondrial inheritance passed exclusively from the maternal lineage
- E)X-linked dominant typically lethal in hemizygous males
Explicação
Hemophilia A (Factor VIII deficiency) is X-linked recessive. This patient is an affected male (XᵃY) who inherited the mutant allele from his carrier mother. His maternal uncle was also affected, consistent with X-linked inheritance affecting males in the same ... Ver explicação completa e trilha adaptativa →