diff --git a/sql/patch_59_60_c.sql b/sql/patch_59_60_c.sql
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+# patch_59_60_c.sql
+#
+# Title:
+#   A patch to fix a couple of inconsistencies in the schema.
+#
+# Description:
+#   A couple of fixes to the schema to do with inconsistencies found
+#   during QC.
+
+# Make the the 'seq_region_start' and 'seq_region_end' fields of the
+# 'karyotype' table UNSIGNED (like they are everywhere else).
+ALTER TABLE karyotype
+  MODIFY COLUMN seq_region_start INT(10) UNSIGNED NOT NULL,
+  MODIFY COLUMN seq_region_end   INT(10) UNSIGNED NOT NULL;
+
+# Make 'seq_region.length' UNSIGNED (we do not like negative lengths).
+ALTER TABLE seq_region
+  MODIFY COLUMN length INT(10) UNSIGNED NOT NULL;
+
+# Insert patch identifier.
+INSERT INTO meta (species_id, meta_key, meta_value)
+  VALUES (NULL, 'patch', 'patch_59_60_c.sql|fix_inconsistencies');