SNP Shot: Genomic Insights

Non-alcoholic fatty liver disease (NAFLD) involves the accumulation of excessive fat within the liver. This fat buildup can cause liver damage similar to that seen in individuals who abuse alcohol, but it occurs in people who do not drink heavily. The liver, a crucial organ in the digestive system, processes food, stores energy, and eliminates waste products, including toxins. While a small amount of fat in the liver is normal, a diagnosis of fatty liver (hepatic steatosis) is made when fat content exceeds 5 to 10 percent of the liver's weight.

Often, the presence of fat deposits in the liver due to NAFLD doesn't cause noticeable symptoms. However, routine blood tests may reveal elevated liver enzyme levels. Some individuals might experience abdominal discomfort or persistent tiredness. A physical exam could reveal a slightly enlarged liver.

In some cases, between 7 and 30 percent of individuals with NAFLD progress to developing inflammation in the liver (non-alcoholic steatohepatitis, or NASH), which leads to liver injury. The body can repair minor liver damage. However, severe or prolonged damage may result in the replacement of healthy liver tissue with scar tissue (fibrosis), leading to irreversible liver disease (cirrhosis). Cirrhosis impairs the liver's ability to function correctly. The symptoms of cirrhosis, which worsen as more of the liver is affected by fibrosis, can include fatigue, weakness, loss of appetite, weight loss, nausea, swelling (edema), and yellowing of the skin and eyes (jaundice). Scarring in the portal vein, which carries blood from the digestive organs to the liver, can lead to increased pressure within this blood vessel (portal hypertension), causing swollen blood vessels (varices) to develop in the digestive system. Rupture of these varices can result in life-threatening bleeding.

NAFLD and NASH are believed to be responsible for many cases of cirrhosis where the underlying cause is unknown (cryptogenic cirrhosis). It is estimated that at least one-third of individuals with NASH will eventually develop cirrhosis. Individuals with NAFLD, NASH, and cirrhosis also face a heightened risk of developing liver cancer (hepatocellular cancer).

NAFLD is most prevalent in middle-aged and older adults, but it can also affect younger people, including children. It's frequently associated with a cluster of conditions known as metabolic syndrome, which includes obesity, type 2 diabetes or pre-diabetes (insulin resistance), elevated blood levels of fats (lipids) such as cholesterol and triglycerides, and high blood pressure (hypertension). However, an individual with NAFLD may not have all or any of the other conditions associated with metabolic syndrome, and conversely, individuals with some or all of those conditions may not have NAFLD.

Inheritance:

The likelihood of developing NAFLD can be increased due to familial inheritance, though the specific inheritance pattern is not yet understood. Variations in multiple genes, along with lifestyle and environmental influences, contribute to the overall risk of developing this complex condition.