Humans, at normal body temperature, radiate most strongly in the infrared at a wavelength of about 10 microns. (A micron is the term commonly used in astronomy for a micrometer or one millionth of a meter.) This image ( which is courtesy of the Infrared Processing and Analysis Center at CalTech), shows a man holding up a lighted match! Which parts of this image do you think have the warmest temperature? How does the temperature of this man’s glasses compare to the temperature of his hand?

SMA type 1 — also called Werdnig-Hoffmann disease — accounts for approximately 45 percent of cases of SMA. Type 1 impacts babies and is usually diagnosed in the first six months of life. They may have one or two copies of the SMN2 gene, which limits their ability to produce the SMN protein needed for motor neuron function.

The following spinal muscular atrophy types are rare and are associated with different genetic mutations than those found in types 0-4. Like types 0-4, each of these forms can vary significantly in terms of severity, quality of life, and life expectancy.

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We know, from looking at an infrared image of a cat, that many things emit infrared light. But many things also reflect infrared light, particularly near infrared light. Near infrared radiation is not related to the temperature of the object being photographed – unless the object is very, very hot.

Other satellites, like the Infrared Astronomy Satellite (IRAS) look up into space and measure the infrared light coming from things like large clouds of dust and gas, stars, and galaxies!Satellites like GOES 6 and Landsat 7 look at the Earth. Special sensors, like those aboard the Landsat 7 satellite, record data about the amount of infrared light reflected or emitted from the Earth’s surface.

Life expectancy for people with type 4 is comparable to that of the general population. Most individuals with type 4 are able to stay mobile throughout their lives.

To make infrared pictures like the one above, we can use special cameras and film that detect differences in temperature, and then assign different brightnesses or false colors to them. This provides a picture that our eyes can interpret. The image at the left (courtesy of SE-IR Corporation, Goleta, CA) shows a cat in the infrared. The orange areas are the warmest and the white-blue areas are the coldest. This image gives us a different view of a familiar animal as well as information that we could not get from a visible light picture.

Are you or a loved one diagnosed with SMA? What advice can you offer others? What questions to you have? Share your experience in the comments below, or start a conversation by posting on your Activities page.

Muscle weakness in the chest can lead to life-threatening breathing difficulties. Children with XL-SMA often have a shortened life expectancy due to respiratory failure, with many not surviving beyond early childhood, though rare cases have lived into adolescence.

Understanding the specific type of SMA that affects you or your loved one is important for tailoring care and managing the condition effectively. Different types of SMA come with unique challenges, symptoms, and treatment options. Knowing the type can help you make informed decisions about medical care, therapies, and support services that improve quality of life.

Type 4 SMA is the mildest form of SMA and accounts for approximately 5 percent of SMA cases. Individuals with type 4 often have four or more SMN2 gene copies. Symptoms usually begin after age 35, although they can sometimes appear as early as 18. Early signs of type 4 may include hand tremors, muscle aches or heaviness, numbness, and cramping.

On mySMAteam, the social network for people with spinal muscular atrophy and their loved ones, more than 2,600 members come together to ask questions, give advice, and share their stories with others who understand life with spinal muscular atrophy.

X-linked infantile SMA (XL-SMA) affects only boys, according to MedlinePlus, and is usually apparent from infancy. Babies with XL-SMA experience significant muscle weakness, areflexia (absent reflexes), and joint deformities like contractures, which cause stiffness in the joints. In severe cases, infants may be born with fractures (broken bones). While some babies may develop motor skills like sitting, they often lose these abilities as the disease progresses.

This image shows the infrared data (appearing as red) composited with visible light data at the blue and green wavelengths. If near infrared is reflected off of healthy vegetation, what do you think the red square shaped areas are in the lower left of the image?

Many things besides people and animals emit infrared light – the Earth, the Sun, and far away things like stars and galaxies do also! For a view from Earth orbit, whether we are looking out into space or down at Earth, we can use instruments on board satellites.

If you have questions about a diagnosis or the best care plan, it’s essential to speak with a health care professional. They can guide you through treatment options, help manage symptoms, and connect you or your loved one with specialists who focus on SMA care.

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Types 0 through 4 of spinal muscular atrophy (SMA) belong to a group called 5q-SMA, which accounts for up to 95 percent of all SMA cases. These types of SMA are caused by mutations (variations) in both copies of the survival motor neuron 1 (SMN1) gene, which leads to a shortage of SMN proteins. These proteins are crucial for motor neurons — the nerve cells that help the brain and spinal cord communicate with the muscles.

This image of a building with a tree and grass shows how Chlorophyll in plants reflect near infrared waves along with visible light waves. Even though we can’t see the infrared waves, they are always there. The visible light waves drawn on this picture are green, and the infrared ones are pale red.

Also known as juvenile SMA or Kugelberg-Welander disease, type 3 is a milder form of SMA that typically develops later in childhood or young adulthood. Approximately 30 percent of SMA cases are type 3. This type can be divided into two subgroups based on age of onset: Type 3a includes children who develop symptoms between 18 months and 3 years old, while type 3b includes children and young adults who develop SMA between 3 and 30 years old. Individuals with type 3 usually have three or four copies of the SMN2 gene.

Despite their severe physical challenges, cognitive development (how their brains work) in babies with type 1 is not affected. Many of these infants are alert, able to recognize their surroundings, and can express emotions through facial expressions.

Since the primary source of infrared radiation is heat or thermal radiation, any object which has a temperature radiates in the infrared. Even objects that we think of as being very cold, such as an ice cube, emit infrared. When an object is not quite hot enough to radiate visible light, it will emit most of its energy in the infrared. For example, hot charcoal may not give off light but it does emit infrared radiation which we feel as heat. The warmer the object, the more infrared radiation it emits.

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Infrared light lies between the visible and microwave portions of the electromagnetic spectrum. Infrared light has a range of wavelengths, just like visible light has wavelengths that range from red light to violet. “Near infrared” light is closest in wavelength to visible light and “far infrared” is closer to the microwave region of the electromagnetic spectrum. The longer, far infrared wavelengths are about the size of a pin head and the shorter, near infrared ones are the size of cells, or are microscopic.

Type 0 is among the rarest and most severe forms of SMA. It affects babies before birth, while they are still in the uterus. Babies with SMA type 0 may have only one copy of the SMN2 gene, which produces very little of the SMN protein.

This second image was taken with special film that can detect invisible infrared waves. This is a false-color image, just like the one of the cat. False-color infrared images of the Earth frequently use a color scheme like the one shown here, where infrared light is mapped to the visible color of red. This means that everything in this image that appears red is giving off or reflecting infrared light. This makes vegetation like grass and trees appear to be red. The visible light waves drawn on this picture are green, and the infrared ones are darker red.

SMA with lower extremity predominance (SMA-LED) leads to muscle weakness and wasting in the lower limbs, particularly affecting the quadriceps (the muscle at the front of the thigh). This weakness can cause difficulty walking and lead to joint deformities in the hips, knees, ankles, and feet. Some people may also experience weakness in the upper limbs.

At birth, babies with SMA type 0 have hypotonia (extremely weak muscle tone) and may show physical deformities due to limited movement in the womb. These infants are often born in a breech position (feet facing downward, rather than the typical head-down position). They may have weak respiratory systems, making it difficult for them to breathe on their own. They may also experience facial paralysis and show minimal response to outside stimuli, such as sound, touch, or light. Infants with type 0 will not achieve motor milestones, such as lifting their heads.

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Many people with type 3 remain mobile, though they may have an abnormal walking pattern (gait) and foot deformities. Some may eventually need to use a wheelchair or require assistance with daily activities such as dressing or using the bathroom. However, life expectancy for individuals with type 3 is typically the same as that of the general population.

With proper care and therapies, individuals with SMA type 2 can live into adulthood. The median survival rate for people with SMA type 2 is 25 years, meaning half of people with the condition live to age 25 or older. Advanced medical support can help extend a person’s life.

Birth can be a medical emergency for these infants. If the baby is unable to breathe independently, a breathing tube may be required, and they will be admitted to a neonatal intensive care unit (NICU). If SMA type 0 is diagnosed before birth, a detailed birth plan can help prepare for immediate medical care. If the diagnosis is unknown at birth, further testing will be needed to determine why breathing difficulties are present.

Shorter, near infrared waves are not hot at all – in fact you cannot even feel them. These shorter wavelengths are the ones used by your TV’s remote control.

It's important to note that much of what we know about life expectancy and SMA symptom progression comes from studies done before the development of newer treatments for the condition. With the introduction of disease-modifying therapies (DMTs), the prognosis (outlook) for children with SMA is improving. Ongoing research and long-term studies will help us understand how these treatments may improve prognosis and slow disease progression.

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This is an infrared image of the Earth taken by the GOES 6 satellite in 1986. A scientist used temperatures to determine which parts of the image were from clouds and which were land and sea. Based on these temperature differences, he colored each separately using 256 colors, giving the image a realistic appearance.Why use the infrared to image the Earth? While it is easier to distinguish clouds from land in the visible range, there is more detail in the clouds in the infrared. This is great for studying cloud structure. For instance, note that darker clouds are warmer, while lighter clouds are cooler. Southeast of the Galapagos, just west of the coast of South America, there is a place where you can distinctly see multiple layers of clouds, with the warmer clouds at lower altitudes, closer to the ocean that’s warming them.

Kennedy’s disease, also known as X-linked spinal and bulbar muscular atrophy, is an adult-onset form of SMA that affects males, according to BetterHealth Channel. The first symptoms usually appear between ages 20 and 50, often including hand tremors and fasciculations (muscle twitching). As the disease progresses, muscle weakness develops in the arms and legs, which can limit mobility. Weakness may also affect the face and tongue, leading to difficulties with speech and swallowing.

In this article, we’ll cover the different types of SMA and how they impact daily life, mobility, and overall health. If you have any questions about your own or a loved one’s SMA diagnosis, a neurologist or genetic counselor who specializes in SMA can provide valuable guidance and support.

SMA with respiratory distress (SMARD) causes muscle weakness and severe breathing difficulties in infants. Early signs of SMARD include difficulty feeding, noisy or labored breathing, and frequent cases of pneumonia. Babies with SMARD may also experience diaphragm paralysis, which makes it difficult or impossible to breathe without the help of a ventilator.

SMA with progressive myoclonic epilepsy (SMA-PME) is a rare form of SMA that causes muscle weakness and seizures. Most children with SMA-PME develop normally in early childhood before showing signs of lower limb weakness. Over time, muscle weakness spreads and causes breathing difficulties, with seizures often starting after muscle symptoms appear.

A second gene, SMN2, produces a small amount of SMN protein, but the SMN1 gene is responsible for most of it. The number of SMN2 copies a person has can influence how severe their form of SMA is. More copies generally mean more SMN protein is produced, which can result in a milder form of the disease.

Children with SMA type 2 experience muscle weakness, especially in the lower limbs, and often lack reflexes. Most children with type 2 develop scoliosis (a curvature of the spine), which can make breathing more difficult as they grow. They are also prone to pneumonia and may have difficulty chewing and swallowing.

The disease progresses rapidly in early childhood, leading to seizures, falls, tremors, and loss of mobility. While some functions, like muscle strength and respiratory activity, may stabilize or mildly improve, most children with SMA-PME do not live beyond late childhood or early adulthood due to respiratory complications.

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Babies with SMA type 1 have muscle weakness on both sides of their bodies, which affects their ability to suck, swallow, and breathe. This makes them more prone to respiratory infections, such as pneumonia. Because of their poor muscle tone, these infants are sometimes described as “floppy.” They will not be able to lift their heads or sit up independently.

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Distal SMA is inherited from one parent, rather than both, and primarily affects the hands and feet. The first sign of distal SMA is often hand cramping in response to cold weather. Symptoms usually begin during adolescence but can also start in childhood or as late as a person’s 30s. Despite the muscle weakness, people with distal SMA typically have a normal life expectancy.

Type 2 SMA, also known as intermediate SMA or Dubowitz disease, accounts for about 20 percent of SMA cases. Type 2 is diagnosed between the ages of 6 months and 18 months. The first noticeable sign is often a failure to meet motor skill milestones, such as sitting or standing independently. However, intellectual development is not affected, and babies with type 2 usually respond to stimulation and engage with those around them.

Symptoms of SMA-LED typically appear in infancy or early childhood, though about a quarter of those affected develop symptoms in adulthood. Unlike other forms of SMA, SMA-LED is inherited in an autosomal dominant pattern, meaning it is passed down from one parent. Despite the muscle weakness, people with SMA-LED have a normal life expectancy.

This is an image of Phoenix, Arizona showing the near infrared data collected by the Landsat 5 satellite. The light areas are areas with high reflectance of near infrared waves. The dark areas show little reflectance. What do you think the black grid lines in the lower right of this image represent?

Children and young adults with type 3 are able to stand and walk, although the first signs of the condition may include frequent falls, difficulty climbing stairs, and general muscle weakness. Muscle weakness typically affects both sides of the body and is more noticeable in the muscles closest to the center of the body, particularly in the legs. Unlike those with types 0-2, people with SMA type 3 generally do not experience significant breathing problems. Cognitive development is also unaffected.

Humans may not be able to see infrared light, but did you know that snakes in the pit viper family, like rattlesnakes, have sensory “pits”, which are used to image infrared light? This allows the snake to detect warm blooded animals, even in dark burrows! Snakes with 2 sensory pits are even thought to have some depth perception in the infrared! (Thanks to NASA’s Infrared Processing and Analysis Center for help with the text in this section.)

Infrared film ‘sees’ the object because the Sun (or some other light source) shines infrared light on it and it is reflected or absorbed by the object. You could say that this reflecting or absorbing of infrared helps to determine the object’s ‘color’ – its color being a combination of red, green, blue, and infrared!

Far infrared waves are thermal. In other words, we experience this type of infrared radiation every day in the form of heat! The heat that we feel from sunlight, a fire, a radiator or a warm sidewalk is infrared. The temperature-sensitive nerve endings in our skin can detect the difference between inside body temperature and outside skin temperature. Infrared light is even used to heat food sometimes – special lamps that emit thermal infrared waves are often used in fast food restaurants!

SMARD tends to progress rapidly in the first two years of life. After this period, the disease may stabilize, and some children experience mild improvements in muscle strength and respiratory function, possibly due to the regeneration of some muscle fibers. However, SMARD still often results in a reduced life expectancy.

Spinal muscular atrophy (SMA) is an inherited neuromuscular disorder — meaning it affects the nerves that control muscle movement. It’s characterized by progressive muscle weakness (hypotonia). There are five main types of SMA — types 0, 1, 2, 3, and 4 — along with a few rarer forms. These types differ based on the age at which symptoms appear, the severity of those symptoms, and the underlying genetic cause.

Life expectancy for babies with SMA type 1 is often related to how well they can breathe. Without advanced respiratory support, many infants with type 1 do not survive beyond age 2.