Myotonic dystrophy and lipoma: a new association.

Myotonic Disorders

Diseases characterized by MYOTONIA, which may be inherited or acquired. Myotonia may be restricted to certain muscles (e.g., intrinsic hand muscles) or occur as a generalized condition. These disorders may be associated with abnormal muscle SODIUM CHANNEL and CHLORIDE CHANNELS. MYOTONIC DYSTROPHY and MYOTONIA CONGENITA represent two relatively common forms of this disorder. Proximal myotonic myopathy often presents with myotonia and muscle pain in early adulthood and later in life thigh muscle weakness and cataracts develop. (From Adams et al., Principles of Neurology, 6th ed, p1392)

Myotonic Dystrophy

An autosomal dominant neuromuscular disorder which usually presents in early adulthood, characterized by progressive muscular atrophy (most frequently involving the hands, forearms, and face), myotonia, frontal baldness, lenticular opacities, and testicular atrophy. Cardiac conduction abnormalities, diaphragmatic weakness, and mild mental retardation may also occur. Congenital myotonic dystrophy is a severe form of this disorder, characterized by neonatal MUSCLE HYPOTONIA, feeding difficulties, respiratory muscle weakness, and an increased incidence of MENTAL RETARDATION. (From Adams et al., Principles of Neurology, 6th ed, pp1423-5; Joynt, Clinical Neurology, 1997, Ch16, pp16-7)

Sleep Apnea, Obstructive

A disorder characterized by recurrent apneas during sleep despite persistent respiratory efforts. It is due to upper airway obstruction. The respiratory pauses may induce HYPERCAPNIA or HYPOXIA. Cardiac arrhythmias and elevation of systemic and pulmonary arterial pressures may occur. Frequent partial arousals occur throughout sleep, resulting in relative SLEEP DEPRIVATION and daytime tiredness. Associated conditions include OBESITY; ACROMEGALY; MYXEDEMA; micrognathia; MYOTONIC DYSTROPHY; adenotonsilar dystrophy; and NEUROMUSCULAR DISEASES. (From Adams et al., Principles of Neurology, 6th ed, p395)

Trinucleotide Repeat Expansion

An increased number of contiguous trinucleotide repeats in the DNA sequence from one generation to the next. The presence of these regions is associated with diseases such as FRAGILE X SYNDROME and MYOTONIC DYSTROPHY. Some CHROMOSOME FRAGILE SITES are composed of sequences where trinucleotide repeat expansion occurs.

Dystrophin

A muscle protein localized in surface membranes which is the product of the Duchenne/Becker muscular dystrophy gene. Individuals with Duchenne muscular dystrophy usually lack dystrophin completely while those with Becker muscular dystrophy have dystrophin of an altered size. It shares features with other cytoskeletal proteins such as SPECTRIN and alpha-actinin but the precise function of dystrophin is not clear. One possible role might be to preserve the integrity and alignment of the plasma membrane to the myofibrils during muscle contraction and relaxation. MW 400 kDa.