Unable to sign TR8 on Self Assessment Return

My Mother is unable to sign TR8 on the Self Assessment return that she submits online each year.She is currently in hospital for a number of problems problems including Gout in her right hand which is preventing her from holding a pen to produce her usual signature but she is able to make a "mark".She is mentally competent according to the Doctors treating her.We do not have a power of attorney.What do we do ? Do we submit the form unsigned?

Hi Barbara BB,
If the return is being submitted online, a signature is not necessary.
You may wish to confirm the reason for the absence of the signature in the 'Any Other Information' section towards the end of the return.
Thank you.