Downs Syndrome and Cri de chat syndrome
There is a genetic problem called "Downs Syndrome" which is best
described in the link http://www.downs-syndrome.org.uk/
which can be reached either directly or by going to the Downs Syndrome
Association UK who have an extensive site to help those born with an
extra chromosome 21 - Downs Syndrome.
There are almost 120 symptoms of Downs Syndrome, which include (thank you,
Sarah Williams):-
She writes that general (but no means specific) symptoms
are:
* Face ; When looked at from the front, the child with Downs
syndrome usually has a round face, and from the side, the face tends to have a
flat profile
* Head ; The back of the head is slightly flattened in most people
with Downs syndrome. This is known as brachycephally.
* Hair ; The hair of children with Downs syndrome is usually soft
and straight.
* Neck ; New born babies with Downs syndrome may have excess skin
over the back of the neck, but this is usually taken up as they grow older.
Children and adults tend to have short, broad necks.
* Mouth ; The mouth cavity is usually slightly smaller than average
and the tongue slightly larger. This can lead to speech problems
* Hands ; The hands tend to be broad, with short fingers. The little
finger sometimes has only one joint instead of two. This finger may also be
slightly curved towards the other fingers. The palm may have only one crease
going across it.
* Feet ; These tend to be stubby and have a wide space between the
first and second toes.
It seems from what little I have read about this subject, that Downs Syndrome
leads to a tendency towards dementia in middle and old aged people, and is also
associated with learning difficulties. Behavioural problems are not
unknown, but then - you don't neccessarily need to be a Downs child to be that,
do you?
Or do you?

Cri de chat syndrome
Another similar syndrome involving hearing, speech and apparent age is the
Cri-de-chat syndrome, so named afte the cat-like cry given off by the
sufferer, It is well described in http://www.sos.se/smkh/2001-110-16/2001-110-16.htm
which is a link to a Danish databank. Many thanks to them.