Category: M

Myotubular myopathy is one of many neuromuscular diseases. It manifests as a cessation or arrest of muscle development at the myotubular stage of development or at about 8-15 weeks gestational age. Diagnosis is possible prenatally due to the characteristic decrease in movement of the fetus. The arrest is related to the failure of vimentin and…

Myhre syndrome, or growth-mental deficiency syndrome of myhre, is an extremely rare disorder. It is an inherited disorder believed to be autosomal dominant and a result of mutation of paternal origin. All six cases reported in the literature have been males, born to parents in their late thirties. The disorder is exceptionally rare (only six…

The term neurasthenia (from the Greek neur, “nerve” and asthenia, “weak”) is attributed to the 19th-century American neurologist George M. Beard, who coined it in 1869. Beard and other physicians began to notice patients who suffered from a constellation of symptoms that included fatigue, muscle soreness, insomnia, difficulty concentrating, general malaise, weakness of extremities, and…

Mulibrey nanism syndrome (MNS), also known as Per-heentupa syndrome, is a hereditary form of dwarfism first described in 1970. The word mulibrey derives from an acronym for the organs most affected in this syndrome: (mu)scle, (li)ver, (br)ain, and (ey)es. Nanism is a synonym for dwarfism.  

Mucopolysaccharide disorders are rare inborn errors of metabolism (IEM) resulting from a failure in mucopolysaccharide metabolism. They are among a larger group of disorders, all of which involve disordered lysosomal (complex carbohydrate) storage. Each has a specific enzymatic defect and genetic transmission (National MPS Society, 2001). Seven groups of syndromes with overlapping features are currently…

Mucha Habermann disease or Habermann disease is one of a subgroup of parapsoriasis and pityriasis. Habermann disease also is known as pityriasis lichenoides. Habermann can occur in an acute form or in a chronic form. As with other diseases within the pityriasis group, it is characterized by skin eruptions. In the acute form, the disease…

Moyamoya disease (MD) is a rare, heritable neurologic disorder characterized by narrowing and occlusion (blockage) of arteries in the neck and brain. Moyamoya is a Japanese term meaning “hazy, like a puff of smoke drifting in the wind.” This nomenclature originates from the appearance of cerebral angiograms (X rays of the brain done after injecting…

Developmental motor speech disorders are a class of disorders that include several forms of dysarthria and apraxia of speech. The dysarthrias were categorized by Darley, Aronson, and Brown (1975) as flaccid, spastic, hyperkinetic, hypokinetic, ataxic, and mixed. The hallmark of a motor speech disorder is mild to severe speech production problems. These problems may include…

Monilethrix is a rare genetic disorder of the hair; it is one of the keratin disorders. Hair keratins have two forms, one acidic and one basic; in monilethrix, one or both of the keratin genes have mutated. The effect of the disorder on the individual’s hair is variable. In most cases the hair is thin…

Moebius syndrome is characterized by paralysis of the facial muscles (diplegia), resulting in an inability to produce facial expressions corresponding to common emotions. This paralysis leaves the child with an unchanging, mask-like face. Cranial nerves VI and VII specifically are affected; involvement of these nerves is a primary criterion for diagnosis of Moebius syndrome. In…