how many porphyria have substrate δ-aminolevulinic acid
CREATE TABLE "biosynthesis" (
  "enzyme" text,
  "location" text,
  "substrate" text,
  "product" text,
  "chromosome" text,
  "ec" text,
  "omim" real,
  "porphyria" text
);
SELECT COUNT("porphyria") FROM "biosynthesis" WHERE "substrate"='δ-Aminolevulinic acid';