Screening for ALS: blood, genetics and more


There are no specific tests to diagnose amyotrophic lateral sclerosis (ALS). To make a diagnosis, a doctor will run tests to rule out other conditions with similar symptoms and indicate changes compatible with ALS.

ALS is a neurological disease that affects the nerves controlling the voluntary muscles, which are the muscles that people use consciously.

This article discusses tests for ALS, the types of tests used by doctors, and how they make a diagnosis.

According to SLA Association, ALS is very difficult to diagnose. There is no specific test or procedure that can conclusively prove that a person has ALS.

One of the reasons for this is that people with this condition can have very different early symptoms. The progression of ALS also varies, further complicating the diagnostic process.

To diagnose ALS, a doctor will perform a physical examination, study a person’s individual and family medical history, and perform a series of tests. The tests aim to look for changes that characterize ALS and rule out other conditions.

In in most cases, the diagnostic tests below will help a doctor diagnose ALS.

Medical imaging tests

Medical imaging, such as MRI, can help diagnose or rule out:

An MRI uses radio waves from a computer and a strong magnetic field inside a large cylindrical tube. It can create detailed images of body tissues, identify abnormal mineral deposits, and assess blood flow.

Nerve or muscle biopsy

To determine if a person has a muscle or nerve disease other than ALS, a doctor may do a muscle or nerve biopsy.

During these tests, a doctor will take a small sample of a nerve or muscle after numbing the skin under local anesthesia. They will then send the sample to a lab, where pathologists will look for signs or markers associated with muscle or nerve conditions other than ALS.

In some cases, a biopsy may also show changes due to ALS, such as a narrowing.

Neurological examination

During a neurological exam, a doctor will assess:

  • sensory and motor skills
  • vision
  • coordination
  • mood
  • behviour
  • mental state
  • balance
  • speech
  • audience
  • reflexes

To perform a neurological exam, a doctor may use tools such as a flashlight or a reflex hammer.

Spine tap

Also known as a lumbar puncture, a lumbar puncture is a procedure that doctors typically use to diagnose:

During a lumbar puncture, a doctor applies a local anesthetic to the skin before inserting a needle into the spinal canal. They take a sample of the fluid called cerebrospinal fluid (CSF) and send it to a lab for analysis.

Electrodiagnostic tests

Electrodiagnostic tests assess the health of muscles, neuromuscular junctions, and the peripheral nervous system. They are a very important diagnostic tool in neurology.

One type of electrodiagnostic test is electromyography (EMG), which involves inserting needles attached to an EMG machine into a muscle. Wires monitor changes in electrical signals in muscles during rest and movement.

A surface EMG uses electrodes, which are less invasive and uncomfortable than needles or fine threads.

To help rule out other conditions, a doctor may also perform another type of electrodiagnostic test called a nerve conduction study (NCS). This test involves sticking recording electrodes connected to an EMG machine to a muscle that sends out a tiny electrical impulse to stimulate the underlying nerves.

An NCS test assesses how well the nerves respond to electrical signals, the strength of the signal, and the speed at which the signals move.

These tests often show certain abnormalities that occur as a result of ALS, and they can become more severe as the disease progresses.

Blood and urine tests

Laboratory screening tests, such as blood and urine tests, can help diagnose or rule out various conditions, including:

  • infections
  • bleeding disorders
  • autoimmune diseases
  • hereditary disorders
  • muscle disorders
  • metabolic conditions
  • fat or protein related disorders
  • certain neurodegenerative diseases


Myelography can help diagnose spinal or spinal cord tumors or compression of spinal fractures or herniated discs.

To perform a myelogram, a doctor injects anesthesia into a space between two vertebrae in the lower back. They then insert a long needle into the spinal canal.

Then, they inject a contrast dye into the spinal canal and do an x-ray or CT scan. In some cases, they may also take a CSF sample with the needle.

It should be noted that healthcare professionals generally do not use this test when investigating possible cases of ALS.

The exact cause of ALS remains unknown. However, it can develop due to a mixture of environmental and genetic factors.

More than 12 genetic mutations appear to influence the development of ALS. According to research, 10% of people without a family history of the disease have genetic mutations linked to ALS.

Researchers believe that certain genetic mutations linked to ALS influence the development and progression of the disease. They can do this by causing changes in the processing of RNA. RNA molecules help produce molecules in cells and contribute to gene activity.

Other genetic mutations associated with ALS appear to cause abnormalities in the recycling of proteins in the body. In this process, the body breaks down non-functional or atypical proteins and rebuilds them.

Certain genetic mutations linked to ALS can also increase a person’s sensitivity to environmental factors that correlate with ALS.

Genetic testing can help identify why a person develops ALS, how the disease may progress, or if someone’s children may be at increased risk for developing ALS in their lifetimes.

If individuals have specific genetic mutations linked to ALS, they may be eligible to participate in clinical drug trials. This knowledge could also help other family members access targeted gene therapy in the future.

A person whose family member has both ALS and one of the genes that cause the disease may decide to have an predictive genetic test for the condition to see if they are at an increased risk of developing it.

To have a genetic test for ALS, a healthcare professional will take a sample of a person’s blood or saliva.

They send these samples to a lab where technicians will isolate the DNA and examine them for mutations associated with ALS.

A person can also have a genetic test for ALS by using a special test kit to take a sample of cells from their cheek, saliva, or blood and send it to a lab testing company in a prepaid envelope.

Cost of genetic testing

If a healthcare professional orders a genetic test for ALS, most health insurance plans will cover the cost. In some cases, a person has to pay the cost of genetic testing out of pocket.

The Program identified ALS offers free genetic testing for ALS to people with ALS and their families.

There is no cure for ALS, but the drugs edaravone and riluzole can help reduce or slow down the progression of his symptoms. People with the disease may also benefit from the following.

Communication assistance

People with ALS who have difficulty speaking can work with a speech-language pathologist to learn ways to cope.

People with the condition can also use devices, such as a computerized speech synthesizer with eye-tracking technology, to allow people to answer questions using eye movement or other non-verbal methods.

People with ALS may also choose to store recordings of their own voices while they can still speak for use when they cannot, in a process called voice banking.

A brain-computer interface system can also help people with the disease communicate or control things, such as a wheelchair, using only brain activity.

Occupational therapy and physiotherapy

A physiotherapist or occupational therapist can help a person with ALS better manage their symptoms by using exercises or special equipment.

Physiotherapists can teach people exercises that help strengthen healthy muscles and improve their range of motion by using stretching exercises to help reduce painful stiffness or muscle changes without overworking the muscles.

Occupational therapists can counsel and teach someone ways to conserve energy and stay mobile for as long as possible using supportive devices, such as wheelchairs, walkers, braces, and handrails.

Breathing support

A person with ALS who has trouble breathing can use a mask to help them breathe. People with the disease can also use mechanical cough assist devices and other techniques to help them generate a stronger cough.

As symptoms of ALS progress and worsen, a person may need to use mechanical ventilation devices that mechanically deflate and inflate the lungs to make breathing easier.

Nutritional support

A nutritionist can help teach people with ALS and their caregivers how to prepare small, healthy meals that contain enough fiber, fluids, and calories and avoid foods that are difficult to swallow or can cause choking.

As symptoms of ALS progress, people may also need to use suction devices to remove excess saliva or fluids and help them avoid choking. When a person with ALS can no longer eat, they may need a feeding tube.

There is no specific test to diagnose ALS. Doctors usually diagnose it by performing a series of tests to find changes compatible with ALS and rule out any other conditions that could explain a person’s symptoms.

People should consider talk to a doctor as soon as possible if any early signs of ALS develop, including unexplained:

  • muscle stiffness or tightness
  • muscle twitching in the legs, arms, shoulders, or tongue
  • muscle cramps
  • muscle weakness in the leg, neck, arm, or chest
  • speech changes
  • difficulty swallowing and chewing


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