dHMN V has a pattern of autosomal dominance, meaning that only one copy of the gene is needed for the development of the disease. However, there is incomplete penetrance of this disorder, meaning that some individuals with the disease-causing mutations will not display any symptoms. Mutations on chromosome 7 have been linked to this disease. It is allelic (i.e., caused by mutations on the same gene) with Charcot–Marie–Tooth disease and with Silver’s Syndrome, a disorder also characterized by small muscle atrophy in the hands.

Another rare form of dHMN V is associated with a splicing mutation in REEP-1, a gene often associated with hereditary spastic neuroplegia.

Distal hereditary motor neuropathy type V (dHMN V) is a particular type of neuropathic disorder. In general, distal hereditary motor neuropathies affect the axons of distal motor neurons and are characterized by progressive weakness and atrophy of muscles of the extremities. It is common for them to be called "spinal forms of Charcot-Marie-Tooth disease (CMT)", because the diseases are closely related in symptoms and genetic cause. The diagnostic difference in these diseases is the presence of sensory loss in the extremities. There are seven classifications of dHMNs, each defined by patterns of inheritance, age of onset, severity, and muscle groups involved. Type V (sometimes notated as Type 5) is a disorder characterized by autosomal dominance, weakness of the upper limbs that is progressive and symmetrical, and atrophy of the small muscles of the hands.

Distal hereditary motor neuronopathies (distal HMN, dHMN), sometimes also called distal hereditary motor neuropathies, are a genetically and clinically heterogeneous group of motor neuron diseases that result from genetic mutations in various genes and are characterized by degeneration and loss of motor neuron cells in the anterior horn of the spinal cord and subsequent muscle atrophy.

Although they can hardly be distinguished from hereditary motor and sensory neuropathies on the clinical level, dHMNs are considered a separate class of disorders.

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".

Influenza's effects are much more severe and last longer than those of the common cold. Most people will recover completely in about one to two weeks, but others will develop life-threatening complications (such as pneumonia). Thus, influenza can be deadly, especially for the weak, young and old, or chronically ill. People with a weak immune system, such as people with advanced HIV infection or transplant patients (whose immune systems are medically suppressed to prevent transplant organ rejection), suffer from particularly severe disease. Pregnant women and young children are also at a high risk for complications.

The flu can worsen chronic health problems. People with emphysema, chronic bronchitis or asthma may experience shortness of breath while they have the flu, and influenza may cause worsening of coronary heart disease or congestive heart failure. Smoking is another risk factor associated with more serious disease and increased mortality from influenza.

According to the World Health Organization: "Every winter, tens of millions of people get the flu. Most are only ill and out of work for a week, yet the elderly are at a higher risk of death from the illness. We know the worldwide death toll exceeds a few hundred thousand people a year, but even in developed countries the numbers are uncertain, because medical authorities don't usually verify who actually died of influenza and who died of a flu-like illness." Even healthy people can be affected, and serious problems from influenza can happen at any age. People over 65 years old, pregnant women, very young children and people of any age with chronic medical conditions are more likely to get complications from influenza, such as pneumonia, bronchitis, sinus, and ear infections.

In some cases, an autoimmune response to an influenza infection may contribute to the development of Guillain–Barré syndrome. However, as many other infections can increase the risk of this disease, influenza may only be an important cause during epidemics. This syndrome has been believed to also be a rare side effect of influenza vaccines. One review gives an incidence of about one case per million vaccinations. Getting infected by influenza itself increases both the risk of death (up to 1 in 10,000) and increases the risk of developing GBS to a much higher level than the highest level of suspected vaccine involvement (approx. 10 times higher by recent estimates).

Reasonably effective ways to reduce the transmission of influenza include good personal health and hygiene habits such as: not touching your eyes, nose or mouth; frequent hand washing (with soap and water, or with alcohol-based hand rubs); covering coughs and sneezes; avoiding close contact with sick people; and staying home yourself if you are sick. Avoiding spitting is also recommended. Although face masks might help prevent transmission when caring for the sick, there is mixed evidence on beneficial effects in the community. Smoking raises the risk of contracting influenza, as well as producing more severe disease symptoms.

Since influenza spreads through both aerosols and contact with contaminated surfaces, surface sanitizing may help prevent some infections. Alcohol is an effective sanitizer against influenza viruses, while quaternary ammonium compounds can be used with alcohol so that the sanitizing effect lasts for longer. In hospitals, quaternary ammonium compounds and bleach are used to sanitize rooms or equipment that have been occupied by patients with influenza symptoms. At home, this can be done effectively with a diluted chlorine bleach.

Social distancing strategies used during past pandemics, such as closing schools, churches and theaters, slowed the spread of the virus but did not have a large effect on the overall death rate. It is uncertain if reducing public gatherings, by for example closing schools and workplaces, will reduce transmission since people with influenza may just be moved from one area to another; such measures would also be difficult to enforce and might be unpopular. When small numbers of people are infected, isolating the sick might reduce the risk of transmission.