| Different
researchers and physicians classify myotubular myopathy and
centronuclear myopathy differently. Some see the two disorders
as separate, while others see them as different extremes of
each other. The researchers at Children’s Hospital Boston
consider myotubular and centronuclear myopathies to be
different extremes of the same disorder. The X-inked MTM (XLMTM),
and its milder variant, centronuclear myopathy (CTNM), are a
clinically and genetically heterogeneous group of disorders
characterized by congenital skeletal muscle weakness which
varies from rapidly fatal in the infantile period (XLMTM) to
relatively nonprogressive and compatible with normal life span
(CTNM). X-linked myotubular myopathy includes a distinct
subset of infants who have a severe myopathy and rarely
survive infancy. The unifying features are skeletal muscle
weakness and myopathic findings on muscle biopsy including the
presence of undifferentiated appearing small myofibers with
characteristic central nuclei or a central clear zone
corresponding to the internuclear space (“myotubes”). XLMTM is
caused by mutations of myotubularin, a novel dual specificity
protein phosphatase whose role in muscle differentiation is
unknown.
Usually, centronuclear myopathy is a pathological diagnosis
that may be given retrospectively to children who survive
infancy and have a milder form of myotubular myopathy.
Individuals with centronuclear myopathy have immature
myofibers with central nuclei but they are more mature than
the myofibers in myotubular myopathy. Centronuclear myopathy
causes general lack of muscle strength and hypotonia and is
very heterogeneous.
(Re: Harvard Neuromuscular Disease Project) |
