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Myasthenia Gravis with Thymoma — SCE Neurology MCQ

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HardPeripheral Neuropathy & NeuromuscularMyasthenia Gravis with ThymomaSCE Neurology

A 59-year-old with few vascular risk factors has recurrent lacunar strokes, executive decline and confluent white-matter disease. His affected father and sister had similar disease after age 50. NOTCH3 testing is negative; neither alopecia nor early spondylosis is present. Which result would best explain this pedigree?

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Correct answer: C — Heterozygous pathogenic HTRA1 variant causing dominant small-vessel disease

Explanation lettering: D = shown as C · C = shown as D

A would usually cause the more severe recessive CARASIL phenotype with younger onset and characteristic alopecia or spondylosis. B conflicts with the negative targeted testing. C causes a different X-linked leukodystrophy phenotype. D is correct: heterozygous HTRA1 variants cause autosomal dominant cerebral small-vessel disease, often later and without the classic extraneurological CARASIL features. E more often causes childhood or young-adult inflammatory vasculopathy and is recessive.

Reference: Heterozygous HTRA1 mutations and autosomal dominant cerebral small-vessel disease: https://pubmed.ncbi.nlm.nih.gov/26063658/