Lactate threshold — MRCP Part 1 MCQ

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HardExercise PhysiologyLactate thresholdMRCP Part 1

A 46-year-old develops rapidly progressive apathy, executive dysfunction, parkinsonism and pyramidal signs. MRI shows asymmetric confluent frontoparietal white-matter lesions involving the corpus callosum; CT shows punctate pericallosal calcifications. CSF is non-inflammatory. Which gene should be prioritised?

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Correct answer: A — CSF1R

The best answer is “CSF1R”. The adult behavioural-cognitive decline, mixed pyramidal and extrapyramidal syndrome, confluent frontoparietal leukoencephalopathy, callosal involvement and punctate calcifications are characteristic of CSF1R-related disorder. Heterozygous CSF1R variants disrupt microglial function and cause the former hereditary diffuse leukoencephalopathy with spheroids phenotype. AARS2 can mimic it, especially in women with ovarian failure, but brain calcifications are unusual. NOTCH3, HTRA1 and GFAP disorders have different imaging and systemic discriminators.

Reference: CSF1R-Related Disorder — GeneReviews: https://www.ncbi.nlm.nih.gov/books/NBK100239/