Researchers from Chinese University have identified eight previously-unknown allergens in some commonly-consumed species of crab, in a breakthrough that will enable doctors to give more specific advice to people who suffer from shellfish allergies.

The team isolated 11 types of proteins from six crab species, which were found to trigger allergies in blood samples from a group of more than 60 patients.

Three of the isolated proteins were previously known to be allergens, while eight were new discoveries, said Professor Leung Ting-fan from CUHK's Faculty of Medicine.

"Why is [the research] important? Because shellfish commonly cause severe allergic reactions, including anaphylaxis," he said.

"Shellfish allergies actually rank the top among all the foods that cause severe allergic reactions that [require] the patient to seek emergency care in hospitals."

He noted that many patients are allergic only to specific types of shellfish, and the new research will allow doctors to give more tailored advice to patients.

"By understanding the specific pattern, we can appropriately advise them to avoid specific types of crab or seafood. This allows us to tailor make our advice and management for patients," he said.

Leung said researchers were particularly interested in one protein identified in the king crab called malate dehydrogenase (MDH), which caused allergic responses in blood samples.

"Of course, other crabs have this MDH, but the MDH in those crabs do not trigger any allergic reaction in the cells of patients, whereas for this king crab, MDH is unique in the sense that patients are really allergic... so we call this a unique kind of crab allergen," he said.

Leung added that one factor may be that king crabs aren't "true crabs" in a taxonomic sense and are more closely related to hermit crabs.