LAUSR

In this issue of the Journal of Nuclear Cardiology, Toutouzas MD, PhD and colleagues in their study ‘‘Visceral adipose tissue phenotype and hypoadiponectinemia are associated with aortic Fluorine-18 fluorodeoxyglucose uptake in patients with familial dyslipidemias’’ add new data to the still emerging field of adipose tissue phenotype and hypoadiponectinemia and their associations with arterial inflammation in patients with familial combined hyperlipidemia (FCH) or heterozygous familial hyperlipidemia (heFH). To enlighten the complex interaction between fat deposition and inflammation of involved tissues, Toutouzas and coworkers made use of the possibilities of Fluorine-18 fluorodeoxyglucose (FDG) PET/CT by quantifying not only the FDG uptake from PET, but also the volumes of abdominal visceral (VAT) and subcutaneous adipose tissue (SAT). Familial dyslipidemias are a group of diseases characterized by hypercholesterolemia, hypertriglyceridemia, or a combination of both accompanied by abnormal high-density lipoprotein cholesterol levels. Familial hypercholesterolemia (FH) is one the most common inherited metabolic disorders and it is characterized by elevated low-density lipoprotein cholesterol (LDL-C) from birth leading to early onset of cardiovascular disease. It is an autosomal dominant disorder with a gene dosage effect. Homozygous patients have higher LDL-C levels and an early onset of cardiovascular disease as compared to heterozygous patients. The prevalence of homozygous FH is about 1:250,000 whereas the prevalence of heterozygous is about 1:250. In these patients, mutations in four different genes can occur: LDL receptor, which is the most common, the LDL receptor binding region of apoliporotein B (Apo B), a rare gain of function of proprotein convertase subtilin/kexin 9 (PCSK9), and loss-of-function mutations in the LDL receptor adaptor protein (LDLRAP). In comparison to familial hypercholesterolemia, the familial combined hyperlipidemia (FCH) is the most common inherited form of dyslipidemia with a prevalence about 1:100. FCH is accompanied by a multitude of metabolic defects such as adipose tissue dysfunction, hepatic steatosis, insulin resistance, and impaired metabolism of lipoprotein particles.