SNP Shot: Genomic Insights

Multiple sclerosis (MS) is a disease where the brain and spinal cord develop damaged areas called lesions. These lesions result from the destruction of the myelin sheath, which normally protects nerve fibers and ensures efficient nerve impulse transmission, as well as damage to nerve cells themselves. MS is classified as an autoimmune disorder, meaning the body's immune system mistakenly attacks its own tissues, specifically those of the nervous system.

MS typically starts in early adulthood, between 20 and 40 years of age. Its symptoms are highly variable; individuals may experience any combination of effects stemming from nervous system damage. Common symptoms include sensory disturbances in the limbs, such as prickling, tingling (paresthesia), numbness, pain, and itching. Some individuals experience Lhermitte's sign, a shock-like sensation down the back and into the limbs, triggered by bending the head forward. Muscle control problems are also frequent, including tremors, muscle stiffness (spasticity), exaggerated reflexes (hyperreflexia), muscle weakness or partial paralysis, difficulty walking, and bladder control issues. Additionally, MS can cause vision problems, such as blurred or double vision, or partial or complete vision loss. Fever-causing infections can exacerbate MS symptoms.

There are several types of MS: relapsing-remitting MS (RRMS), secondary progressive MS (SPMS), primary progressive MS (PPMS), and progressive-relapsing MS (PRMS). RRMS is the most common, affecting about 80% of people with MS. It is characterized by periods of symptom flare-ups (clinical attacks) followed by periods of symptom absence (remission). The causes of these attacks and remissions are not known. After approximately 10 years, RRMS often transitions into SPMS. In SPMS, remissions cease, and symptoms continuously worsen.

PPMS is the next most prevalent form, affecting roughly 10 to 20% of individuals with MS. It is defined by steadily worsening symptoms from the onset, without clinical attacks or remissions. PPMS usually starts later in life, around age 40, compared to other forms of MS.

PRMS is a rare form of MS that initially resembles PPMS, with constant symptoms. However, individuals with PRMS also experience clinical attacks, characterized by a worsening of symptoms.

Inheritance:

The inheritance pattern of MS is currently unknown. However, there is evidence suggesting a genetic component, as the condition tends to cluster in families. Siblings and children of individuals with MS have a higher risk of developing the condition compared to the general population.