With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Chester Bennington is a writer of songs.
text_B: Ribose-5-phosphate isomerase deficiency -LRB- RPI deficiency , OMIM # 608611 -RRB- is a human disorder caused by mutations in the pentose phosphate pathway enzyme ribose-5-phosphate isomerase .. pentose phosphate pathway. pentose phosphate pathway. enzyme. enzyme. ribose-5-phosphate isomerase. ribose-5-phosphate isomerase. With a single diagnosed patient over a 27-year period , RPI deficiency is currently the rarest disease in the world .. rarest disease. Rare disease
not_related.