Hello there basically Klippel Trenauney Syndrome also known as Angio-osteohypertophy syndrome has to do with
1} Combined vascular malformation
of the capillary, venous and lymphatic types;
2) Varicosities of unusual distribution, in particular the later an various anomaly observed during infancy or childhood and
3) Limb enlargement.
Your sons cough
is mostly due to acid reflux
rather than the syndrome so if you take corrective steps for controlling the reflux using anti-emetic/reflux medication
the cough would be controlled. As the child grows up reflux symptoms tends to decrease. If not you need to follow up with GI for further eval... Has chest x-ray been done with routine blood tests to rule out infective causes of cough???