Inheritance: X-linked
Gene location: Xq28
Gene product affected: muscle emerin
Clinical features:
(1) A male presents during childhood with a slowly progressive weakness.
(2) The patient may develop weakness in the upper arms followed by a flexion contraction at the elbows.
(3) The patient may develop weakness in the anterior compartment of the lower leg followed by tightening of the Achilles tendon.
(4) The patient may show extension of the neck and/or rigidity of the spine.
(5) The patient may develop a cardiac conduction defect which may necessitate placement of a cardiac pacemaker to avoid sudden death.
Laboratory findings:
(1) Serum CK may be increased.
(2) Emerin is decreased in skin biopsies.
The EMG shows nonspecific changes.
A muscle biopsy shows nonspecific chronic myopathic features. Analysis for muscle emerin shows it to be reduced.
