Clinical negligence or maladministration?

[Mharhi]

If a doctor did not refer a patient for a rare pre-existing medical condition, as they didn't have it on their computer system due to an admin error, would this be negligence or maladministration?

Not sure. Negligence requires these 4 criteria to be met:

Elements of the case
A plaintiff must establish all four elements of the tort of negligence for a successful medical malpractice claim.
A duty was owed: a legal duty exists whenever a hospital or health care provider undertakes care or treatment of a patient.
A duty was breached: the provider failed to conform to the relevant standard care.
The breach caused an injury: The breach of duty was a proximate cause of the injury.
Damage: Without damage (losses which may be pecuniary or emotional), there is no basis for a claim, regardless of whether the medical provider was negligent. Likewise, damage can occur without negligence, for example, when someone dies from a fatal disease.

I think that if you were a patient of the Dr you have satisfied the first part, the second part, yes probably but you haven't said if anything actually happened (the injury) and that if it did, whether it was actually contributed to by the failure to send the letter.

If you would have died anyway no matter how fast the letter was sent then well the breach wouldn't have been a cause of the injury?

Bartlet is probably lots better at this than I am! More details would help.