= Solution
The ascending-colon tumors carry the exon-5 <frameshift mutation> in $3/4$ sampled patients, transverse tumors in $1/2$, and descending and sigmoid tumors in $0/2$ each. Grouping these gives \b[$4/6$ proximal tumors versus $0/4$ distal tumors with the repeat alteration], suggesting proximal enrichment of this molecular subtype. The matched samples show a one-allele alteration in the adjacent tissue of patients 1 and 7, whereas patients 5 and 9 have tumor-associated alterations without a detected alteration in their matched normal sample.
This is a small case series, and all ten patients already have tumors. \b[It cannot determine whether a region has a higher absolute risk of transformation], nor establish defective <DNA mismatch repair> from one altered repeat alone. Larger location-matched series, population denominators, testing of additional <microsatellites> and direct assessment of <DNA mismatch repair> components are needed to support those stronger claims.
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