WBR282

Author	PageAuthor::Gerald Chi
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathology
Sub Category	SubCategory::Cardiology
Prompt	[[Prompt::A 29-year-old female presents with a three-year history of increasing dyspnea on exertion associated with chest tightness and lightheadedness. Physical examination is notable for palpable double apical impulses, fourth heart sounds, and systolic murmurs at the left lower sternal border that are augmented after the occurrence of premature ventricular contractions and weakened by phenylephrine administration. Echocardiography shows systolic anterior motion of the mitral valve. Which of the following diseases has the same pattern of inheritance as does the case?]]
Answer A	AnswerA::Huntington disease
Answer A Explanation	AnswerAExp::Huntington disease is inherited in an autosomal dominant mode.
Answer B	AnswerB::Cystic fibrosis
Answer B Explanation	AnswerBExp::Cystic fibrosis is inherited in an autosomal recessive mode.
Answer C	AnswerC::Kartagener syndrome
Answer C Explanation	AnswerCExp::Kartagener syndrome is inherited in an autosomal recessive mode.
Answer D	AnswerD::Tay-Sachs disease
Answer D Explanation	AnswerDExp::Tay-Sachs disease is inherited in an autosomal recessive mode.
Answer E	AnswerE::Leber hereditary optic neuropathy
Answer E Explanation	AnswerEExp::Leber hereditary optic neuropathy is an example of mitochondrial inheritance.
Right Answer	RightAnswer::A
Explanation	[[Explanation::Familial form of hypertrophic cardiomyopathy (HCM) is inherited as an autosomal dominant trait and involves missense mutations in genes that encode for myosin heavy chain or sarcomere proteins. Some patients are asymptomatic, while others may have symptoms of dyspnea, chest pain, palpitations, lightheadedness, fatigue, syncope, and sudden cardiac death. The development of dyspnea on exertion is indicative of stiffened left ventricle as evidenced by a fourth heart sound. Hypertrophied interventricular septum with systolic anterior motion of the mitral valve may result in subaortic obstruction of the left ventricular outflow tract that produces double tap of apical impulse as well as pulsus bisferiens. Heart murmurs of HCM are intensified with conditions of decreased preload or after long cardiac cycles and softened with conditions of increased afterload. Educational Objective: References: ]]
Approved	Approved::No
Keyword	WBRKeyword::Huntington disease
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::