What are differences between Arthrochalasia Type A and B of Ehlers-Danlos Syndrome?

Ehlers-Danlos Syndrome (EDS) is a rare group of genetic
disorders of connective tissues that bind muscles, ligaments, organs and
skin.

Arthrochalasia is defined as excessive looseness of
joints in which the patient may be described as
“double-jointed”.

In the Arthrochalasia type of EDS there
is a mutation of either gene COL1A1 or COL1A2, resulting in arthrochalasia type A or
type B, respectively.  The gene is dominant such that it can be inherited from one
parent, resulting in disease.  More often, however, EDS occurs sporadically due to
genetic mutation.

Patients with the Arthrochalasia type of
EDS have skin hyperelasticity (redundant, easily stretched skin), Joint hyper-mobility,
fragile tissues, easy bruising, poor muscle tone, kyphoscoliosis (abnormal curvature of
the spine) and mild loss of bone density (osteopoenia) on X-ray examination of the
skeleton.  The arthrochalasia usually causes congenital (at birth) presence of
dislocated hip(s), and a tendency for recurrent hip subluxations/dislocations later on.
 Subluxation means partial dislocation.

As a practical
matter, there is little difference between Arthrochalasia Types A and B.  Instead, the
distinction is made on a genetic basis, depending on which of the collagen genes has
mutated, or which abnormal collagen gene has been inherited.