Q: Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.
Context: McLeod syndrome and chorea-acanthocytosis are classified with the so-called neuroacanthocytosis group of syndromes. Both lead to progressive basal ganglia degeneration and were not easily distinguished in the past. With the discovery of their molecular bases, mutations of the X-linked gene XK and autosomal recessive mutations of the gene coding for chorein, respectively, the two phenotypes can now be differentiated and extend the diagnostic spectrum in patients presenting with chorea. The present review compares the two conditions and proposes a practical approach to diagnosis and treatment. Better-defined disease concepts should eventually replace the umbrella term of "neuroacanthocytosis." Animal models are needed to understand the underlying mechanisms. A final common pathway is likely for the pathogenesis of these conditions and is most probably shared with Huntington's disease.
Question: Mutation of which gene is associated with McLeod syndrome?
A:
xk