SNP Shot: Genomic Insights

Cerebrotendinous xanthomatosis (CTX) is a condition where the body has trouble processing certain fats (lipids), leading to their build-up in various tissues. Specifically, individuals with CTX struggle to break down certain types of cholesterol. This results in the formation of fatty, yellowish nodules called xanthomas, which are most commonly found in the brain and tendons (connective tissues linking muscles to bones). The name of the disorder reflects these key features: "cerebro-" refers to the brain, and "-tendinous" refers to the tendons.

Neurological issues often arise in early adulthood for people with CTX. These problems are believed to be caused by the accumulation of fats and the increasing presence of xanthomas within the brain. These issues can include recurrent seizures (epilepsy), movement disorders, speech difficulties (dysarthria), numbness or tingling in the limbs (peripheral neuropathy), cognitive decline (dementia), hallucinations, and depression. Xanthomas can also affect the myelin sheath, a fatty coating that insulates and protects nerves, leading to its breakdown and disrupting nerve signals in the brain. Furthermore, the build-up of excess lipids can cause brain tissue degeneration (atrophy), contributing to neurological problems.

Tendon xanthomas usually begin to develop in early adulthood. They commonly appear in tendons located in the hands, elbows, knees, neck, and the Achilles tendon (connecting the heel to the calf muscles). These xanthomas can cause discomfort and limit tendon flexibility. While many individuals with CTX develop tendon xanthomas, they may not always be easily visible under the skin.

Other symptoms of CTX can include clouding of the eye lenses (cataracts), chronic diarrhea during childhood, a decreased ability to produce and release bile (cholestasis) which can cause yellowing of the skin or eyes (jaundice), and bones that become progressively weak and prone to fractures (osteoporosis). Individuals with CTX also have a higher risk of developing cardiovascular disease or respiratory failure due to lipid accumulation in the heart or lungs, respectively. Without treatment, the symptoms of CTX tend to worsen over time, although the severity of the condition can vary significantly from person to person.

Inheritance:

CTX is an autosomal recessive disorder. This means that a person must inherit two copies of the mutated gene (one from each parent) to develop the condition. Parents who each carry one copy of the mutated gene are typically unaffected and do not show any symptoms of CTX.