A hereditary CNS demyelinating disease is a demyelinating central nervous system disease that is primarily due to an inherited genetic condition. (This is in contrast to autoimmune demyelinating conditions, such as multiple sclerosis, or conditions such as central pontine myelinolysis that are associated with acute acquired insult.)

Examples include:

- Alexander disease

- Canavan disease

- Krabbe disease

- leukoencephalopathy with vanishing white matter

- megalencephalic leukoencephalopathy with subcortical cysts

- metachromatic leukodystrophy

- X-linked adrenoleukodystrophy

Harderoporphyria is a rare disorder of heme biosynthesis, inherited in an autosomal recessive manner caused by specific mutations in the "CPOX" gene. Mutations in "CPOX" usually cause hereditary coproporphyria, an acute hepatic porphyria, however the K404E mutation in a homozygous or compound heterozygous state with a null allele cause the more severe harderoporphyria. Harderoporphyria is the first known metabolic disorder where the disease phenotype depended on the type and location of the mutations in a gene associated with multiple disorders.

In contrast with other porphyrias, which typically present with either cutaneous lesions after exposure to sunlight or acute neurovisceral attack at any age (most commonly in adulthood), harderoporphyria is characterized by jaundice, anemia enlarged liver and spleen, often presenting in the neonatal period. Later in life, these individuals may present with photosensitivity similar to that found in cutaneous porphyrias.

Biochemically, harderoporphyria presents with a distinct pattern of increased harderoporphyrin (2-vinyl-4,6,7-tripropionic acid porphyrin) in urine and particularly in feces, a metabolite that is not seen in significant quantities in any other porphyria. Enzyme tests show markedly reduced activity of coproporphyrinogen oxidase, compared to both unaffected individuals and those affected with hereditary coproporphyria, consistent with recessive inheritance.

Harderoporphyria is a rare condition, with less than 10 cases reported worldwide. It may be underdiagnosed, as it does not have the typical presentation associated with a porphyria. It was identified as a variant type of coproporphyria in 1983, in a family with three children identified at birth with jaundice and hemolytic anemia. There is no standard treatment for harderoporphyria; care is mainly focused on the management of symptoms.

Onset occurs in infancy or early childhood, usually before 3 years of age. Progression is slow until the teenage years at which point it may accelerate, resulting in severe disability.

Symptoms are usually more severe and rapidly progressive than in the other more common Charcot–Marie–Tooth diseases. Some patients may never walk and solely use wheelchairs by the end of their first decade, while others may need only a cane (walking stick) or similar support through life.

Dejerine–Sottas disease is characterized by moderate to severe lower and upper extremity weakness and loss of sensation, which occur mainly in the lower legs, forearms, feet and hands. Loss of muscle mass and reduced muscle tone can occur as the disease progresses. Other symptoms may include pain in the extremities, curvature of the spine, clawed hands, foot deformities, ataxia, peripheral areflexia, and slow acquisition of motor skills in childhood. Symptoms that are less common can include limitation of eye movements, other eye problems such as nystagmus or anisocoria, or mild hearing loss.

Meige lymphedema, also known as Meige disease, Late-onset lymphedema, and Lymphedema hereditary type 2, is an inherited disease in which patients develop lymphedema. The onset is between the ages of 1 and 35. Other causes of primary lympoedema include Milroy's disease which occurs before the age of 1, and lymphoedema tarda which occurs after the age of 35.

Meige disease,(Hereditary lymphedema type II), has its onset around the time of puberty. It is an autosomal dominant disease. It has been linked to a mutations in the ‘forkhead’ family transcription factor (FOXC2) gene located on the long arm of chromosome 16 (16q24.3). It is the most common form of primary lymphedema, and about 2000 cases have been identified. Meige disease usually causes lymphedema of the legs, however, other areas of the body may be affected, including the arms, face and larynx. Yellow toe nails occur in some individuals.

Hereditary inclusion body myopathies (HIBM) are a heterogeneous group of very rare genetic disorders which have different symptoms. Generally, they are neuromuscular disorders characterized by muscle weakness developing in young adults. Hereditary inclusion body myopathies comprise both autosomal recessive and autosomal dominant muscle disorders that have a variable expression (phenotype) in individuals, but all share similar structural features in the muscles.

HIBMs are a group of muscle wasting disorders, which are uncommon in the general world population. One autosomal recessive form of HIBM is known as IBM2 or GNE myopathy, which is a common genetic disorder amongst people of Iranian Jewish descent. IBM2 has also been identified in other minorities throughout the world, including people of Asian (Japanese and others), European, and South American origin, as well as Muslim people in the Middle Eastern, Palestinian, and Iranian origin. In Japan and many East Asian countries, this disorder is known as Distal Myopathy with Rimmed Vacuoles (DMRV).

IBM2 causes progressive muscle weakness and wasting. Muscle wasting usually starts around the age of 20 – 30 years, although young onset at 17 and old onset at 52 has been recorded. As such, it affects the most productive times of our lives. It can progress to marked disability within 10 – 15 years, confining many people with IBM2 to a wheelchair. The weakness and severity can vary from person to person. In some, weakness in the legs is noticed first. In few others, the hands are weakened more rapidly than the legs. Weakness is progressive, which means the muscle becomes weaker over time. IBM2 does not seem to affect the brain, internal organs or sensation. The quadriceps are relatively spared, and remain strong until the late stages of disease, which is the reason IBM2 is often referred to as Quadriceps Sparing Myopathy (QSM).

Hereditary sensory and autonomic neuropathy type I (HSAN I) or hereditary sensory neuropathy type I (HSN I) is a group of autosomal dominant inherited neurological diseases that affect the peripheral nervous system particularly on the sensory and autonomic functions. The hallmark of the disease is the marked loss of pain and temperature sensation in the distal parts of the lower limbs. The autonomic disturbances, if present, manifest as sweating abnormalities.

The beginning of the disease varies between adolescence and adulthood. Since affected individuals cannot feel pain, minor wounds or blisters in the painless area may not be immediately recognized and can develop into extensive and deep foot ulcerations. Once infection occurs, the complications such as inflammation and progressive destruction of the underlying bones may follow and may require amputation of the surrounding area.

HSAN I is the most common type among the five types of HSAN. As a heterogeneous group of diseases, HSAN I can be divided into five subtypes HSAN IA-E. Most of the genes associated with the diseases have been identified. However, the molecular pathways leading to the manifestation of the diseases are not fully understood. Therefore, the potential targets for therapeutic interventions are not known. Moreover, gene-based therapies for patients with the diseases are not available to date, hence supportive care is the only treatment available for the patients.

The most common presentation of Milroy Disease is bilateral lower extremity lymphedema, and may also be accompanied by hydrocele.

Some early signs of HIBMs includes:

- Difficulty walking on heels, and difficulty running;

- Weak index finger;

- Frequent loss of balance.

- On muscle biopsy, the typical finding includes inclusion bodies, rimmed vacuoles and accumulation of aberrant proteins similar to those found in senile plaques of Alzheimer's disease (amyloid beta, hyperphosphorylated tau, amongst others)

In an individual with dHMN V, electromyography will show pure motor neuropathy, patterns of weakness without upper motor neuron damage, in the hands. Tendon reflexes will also appear normal. Clinical, electrophysiological, and pathological testing will show a lack of damage to sensory neurons, differentiating this disease from CMT.

Onset usually occurs within the first two decades of life, commonly in the teenage years or the twenties. Life expectancy is normal. High arch of the foot (pes cavus) is common. Patients also have trouble controlling their hands, due to muscle loss on the thumb side of the index finger and palm below the thumb. It is rare for a person with this disorder to lose the ability to walk, though changes in gait may occur later in life.

Frequency of this disorder is unknown.

Megalencephalic leukoencephalopathy with subcortical cysts (MLC, or Van der Knaap disease) is a form of hereditary CNS demyelinating disease. It belongs to a group of disorders called leukodystrophies.

It is associated with MLC1. Van der Knaap disease is named after Dutch neurologist Marjo van der Knaap.

At the beginning, affected individuals often notice the loss of pain and temperature sensation or all sensory modalities in their feet. As the disease progresses, the sensory abnormalities may extend up to the knees. However, they often do not notice sensory loss for a long time. Many affected individuals only become aware of the disease when they notice painless injuries and burns or when they seek medical advice for slowly healing wounds or foot ulcers. Foot ulcerations may appear due to permanent pressure, such as long walks or badly fitting shoes. Minor wounds or blisters may then lead to deep foot ulcerations. Once infection occurs, complications such as inflammation and destruction of the underlying bones may follow. Affected individuals who do not lose sensation may experience spontaneous pain. In addition, many affected individuals exhibit, to a variable degree, symmetrical distal muscle weakness and wasting.

HSAN I is characterized by marked sensory disturbances mainly as the loss of pain and temperature sensation in the distal parts of the lower limbs. The loss of sensation can also extend to the proximal parts of the lower limbs and the upper limbs as the disease progresses. Some affected individuals do not lose sensation, but instead experience severe shooting, burning, and lancinating pains in the limbs or in the trunk. Autonomic disturbances, if present, manifest as decreased sweating. The degree of motor disturbances is highly variable, even within families, ranging from absent to severe distal muscle weakness and wasting.

The disease progresses slowly, but often disables the affected individuals severely after a long duration. The onset of the disease varies between the 2nd and 5th decade of life, albeit congenital or childhood onset has occasionally been reported. With the progression of the disease, the affected individuals lose the ability to feel pain in their feet and legs. Minor injuries in the painless area can result in slow-healing wounds which, if not immediately recognized, can develop into chronic ulcerations. Once infection occurs, these ulcerations can result in severe complications that lead to foot deformity, such as inflammation of the underlying bones, spontaneous bone fractures, and progressive degeneration of weight-bearing joints. Furthermore, foot deformity promotes skin changes such as hyperkeratosis at pressure points. These complications may necessitate amputation of the affected foot.

Biopsies of severely affected sural nerve (short saphenous nerve) in patients with HSAN I showed evidence of neuronal degeneration. Only a very few myelinated fibers were observed some of which showed a sign of primary (segmental) demyelination. A reasonable number of unmyelinated axons remained, although the presence of stacks of flattened Schwann cell processes suggested unmyelinated axon loss. Electrophysiological testing provides additional evidence that neuronal degeneration underlies the disease. Sensory potentials are usually absent in the lower limbs but are often recordable or even normal in the upper limbs of the patients. In addition, motor conduction is slow, possibly implying a demyelinating process.

Milroy's disease (MD) is a familial disease characterized by lymphedema, commonly in the legs, caused by congenital abnormalities in the lymphatic system. Disruption of the normal drainage of lymph leads to fluid accumulation and hypertrophy of soft tissues. It is also known as Milroy disease, Nonne-Milroy-Meige syndrome and hereditary lymphedema.

It was named by Sir William Osler for William Milroy, a Canadian physician, who described a case in 1892, though it was first described by Rudolf Virchow in 1863.

Affected male and carrier female dogs generally begin to show signs of the disease at two to three months of age, with proteinuria. By three to four months of age, symptoms include for affected male dogs: bodily wasting and loss of weight, proteinuria & hypoalbuminemia. Past nine months of age, hypercholesterolemia may be seen. In the final stages of the disease, at around 15 months of age for affected males, symptoms are reported as being renal failure, hearing loss and death. Since the condition is genetically dominant, diagnosis would also include analysis of the health of the sire and dam of the suspected affected progeny if available.

Clinically, three distinct patterns of palmoplantar keratoderma may be identified: diffuse, focal, and punctate.

Spinocerebellar ataxia (SCA) is one of a group of genetic disorders characterized by slowly progressive incoordination of gait and is often associated with poor coordination of hands, speech, and eye movements. A review of different clinical features among SCA subtypes was recently published describing the frequency of non-cerebellar features, like parkinsonism, chorea, pyramidalism, cognitive impairment, peripheral neuropathy, seizures, among others. As with other forms of ataxia, SCA frequently results in atrophy of the cerebellum, loss of fine coordination of muscle movements leading to unsteady and clumsy motion, and other symptoms.

The symptoms of an ataxia vary with the specific type and with the individual patient. In general, a person with ataxia retains full mental capacity but progressively loses physical control.

Samoyed hereditary glomerulopathy [glo-mer″u-lop´ah-the] (SHG) is an hereditary noninflammatory disease of the renal glomeruli, occurring in the Samoyed breed of dog. The disease has been shown to be a model for hereditary nephritis (HN) in humans in that the disease resembles that of the human disease. Because of this, it is sometimes referred to by the name given to the disease in humans when referring to the conditions in Samoyed dogs. Alternatively, it may also be known as X-linked hereditary nephritis. Genetically, the trait is inherited as a sex-linked, genetically dominant disease, and thus affects male dogs to a greater degree than female dogs, since males only have one X chromosome.

Congenital dyserythropoietic anemia type II (CDA II), or hereditary erythroblastic multinuclearity with positive acidified serum lysis test (HEMPAS) is a rare genetic anemia in humans characterized by hereditary erythroblastic multinuclearity with positive acidified serum lysis test.

Dejerine–Sottas disease, also known as Dejerine–Sottas syndrome, Dejerine–Sottas neuropathy, progressive hypertrophic interstitial polyneuropathy of childhood and onion bulb neuropathy (and, "hereditary motor and sensory polyneuropathy type III" and "Charcot–Marie–Tooth disease type 3"), is a hereditary neurological disorder characterised by damage to the peripheral nerves and resulting progressive muscle wasting. The condition is caused by mutations in a various genes and currently has no known cure.

The disorder is named for Joseph Jules Dejerine and Jules Sottas, French neurologists who first described it.

Neuromuscular disease can be caused by autoimmune disorders, genetic/hereditary disorders and some forms of the collagen disorder Ehlers–Danlos Syndrome, exposure to environmental chemicals and poisoning which includes heavy metal poisoning. The failure of the electrical insulation surrounding nerves, the myelin, is seen in certain deficiency diseases, such as the failure of the body's system for absorbing vitamin B-12

Diseases of the motor end plate include myasthenia gravis, a form of muscle weakness due to antibodies against acetylcholine receptor, and its related condition Lambert-Eaton myasthenic syndrome (LEMS). Tetanus and botulism are bacterial infections in which bacterial toxins cause increased or decreased muscle tone, respectively.Muscular dystrophies, including Duchenne's and Becker's, are a large group of diseases, many of them hereditary or resulting from genetic mutations, where the muscle integrity is disrupted, they lead to progressive loss of strength and decreased life span.

Further causes of neuromuscular diseases are :

Inflammatory muscle disorders

- Polymyalgia rheumatica (or "muscle rheumatism") is an inflammatory condition that mainly occurs in the elderly; it is associated with giant-cell arteritis(It often responds to prednisolone).

- Polymyositis is an autoimmune condition in which the muscle is affected.

- Rhabdomyolysis is the breakdown of muscular tissue due to any cause.

Tumors

- Smooth muscle: leiomyoma (benign)

- Striated muscle: rhabdomyoma (benign)

Diffuse palmoplantar keratoderma is a type of palmoplantar keratoderma that is characterized by an even, thick, symmetric hyperkeratosis over the whole of the palm and sole, usually evident at birth or in the first few months of life. Restated, diffuse palmoplantar keratoderma is an autosomal dominant disorder in which hyperkeratosis is confined to the palms and soles. The two major types can have a similar clinical appearance:

- "Diffuse epidermolytic palmoplantar keratoderma" (also known as "Palmoplantar keratoderma cum degeneratione granulosa Vörner," "Vörner's epidermolytic palmoplantar keratoderma", and "Vörner keratoderma") is one of the most common patterns of palmoplantar keratoderma, an autosomal dominant condition that presents within the first few months of life, characterized by a well-demarcated, symmetric thickening of palms and soles, often with a "dirty" snakeskin appearance due to underlying epidermolysis.

- "Diffuse nonepidermolytic palmoplantar keratoderma" (also known as "Diffuse orthohyperkeratotic keratoderma," "Hereditary palmoplantar keratoderma," "Keratosis extremitatum progrediens," "Keratosis palmoplantaris diffusa circumscripta," "Tylosis," "Unna–Thost disease", and "Unna–Thost keratoderma") is inherited as an autosomal dominant condition and is present from infancy, characterized by a well-demarcated, symmetric, often "waxy" keratoderma involving the whole of the palms and soles.

The anemia associated with CDA type II can range from mild to severe, and most affected individuals have jaundice, hepatosplenomegaly, and the formation of hard deposits in the gallbladder called bilirubin gallstones. This form of the disorder is usually diagnosed in adolescence or early adulthood. An abnormal buildup of iron typically occurs after age 20, leading to complications including heart disease, diabetes, and cirrhosis.

Neonatal Hemochromatosis is a rare and severe liver disease of unknown origin, though research suggests that it may be alloimmune condition. Its characteristics are similar to hereditary hemochromatosis, where iron deposition causes damage to the liver and other organs and tissues.

Neuromuscular disease is a very broad term that encompasses many diseases and ailments that impair the functioning of the muscles, either directly, being pathologies of the voluntary muscle, or indirectly, being pathologies of nerves or neuromuscular junctions.

Neuromuscular diseases are those that affect the muscles and/or their direct nervous system control, problems with central nervous control can cause either spasticity or some degree of paralysis (from both lower and upper motor neuron disorders), depending on the location and the nature of the problem. Some examples of central disorders include cerebrovascular accident, Parkinson's disease, multiple sclerosis, Huntington's disease and Creutzfeldt–Jakob disease. Spinal muscular atrophies are disorders of lower motor neuron while amyotrophic lateral sclerosis is a mixed upper and lower motor neuron condition.

In 1993, A. E. Hardnig proposed to classify hereditary motor neuropathies into seven groups based on age at onset, mode of inheritance, and presence of additional features. This initial classification has since been widely adopted and expanded and currently looks as follows:

Note: Acronym "HMN" is also used interchangeably with "DHMN".