There are four basic groups of deafblind people:

This can be caused by rare genetic conditions or illnesses such as mumps. If the pregnant mother has Rubella, this can cause the unborn child to be deaf and blind.

People born deafblind will have great difficulty acquiring any language, and may never have any formal language, but could develop a simple communication method.

Around 4-6% of all people born with a hearing loss have a genetic condition called Usher syndrome, in which they are born with a hearing loss and then develop Retinitus Pigmentosa (R.P.) People who are born deaf may have sign language as their first language, and therefore be able to adapt their communication method to either 'hands on' signing - when the deaf person with a sight loss holds onto the hands of the interpreter as they sign - or 'visual frame' signing - when the interpreter finds the most advantageous place to sign to suit the deafblind person. This may be several feet away or close to the interpreter's face.

They would need to develop new skills though for mobility and daily living.

This is a small group of people. They may have the advantage of having Braille skills, in which case, they still have access to some information. They may also already have mobility skills, which would need to be adapted. The biggest problem may be adapting their communication skills to a manual communication system.

Many people may develop deafblindness unexpectedly, without illness or genetic cause. Approximately 65% of deafblind people are elderly, who perhaps suddenly or gradually lose sight and hearing. This group of people has all the disadvantages of being deafblind as well as the problems that age can bring.