phytosterols and Xanthomatosis--Cerebrotendinous

Familial hypercholesterolemia (FH) is a genetic disorder characterized by elevated low-density lipoprotein (LDL) cholesterol and premature cardiovascular disease, with a prevalence of approximately 1 in 200-500 for heterozygotes in North America and Europe. Monogenic FH is largely attributed to mutations in the LDLR, APOB, and PCSK9 genes. Differential diagnosis is critical to distinguish FH from conditions with phenotypically similar presentations to ensure appropriate therapeutic management and genetic counseling. Accurate diagnosis requires careful phenotyping based on clinical and biochemical presentation, validated by genetic testing. Recent investigations to discover additional genetic loci associated with extreme hypercholesterolemia using known FH families and population studies have met with limited success. Here, we provide a brief overview of the genetic determinants, differential diagnosis, genetic testing, and counseling of FH genetics.

Topics: Apolipoprotein B-100; Cholesterol Ester Storage Disease; Diagnosis, Differential; Genetic Counseling; Genetic Predisposition to Disease; Genetic Testing; Humans; Hypercholesterolemia; Hyperlipoproteinemia Type II; Intestinal Diseases; Lipid Metabolism, Inborn Errors; Phytosterols; Proprotein Convertase 9; Proprotein Convertases; Receptors, LDL; Serine Endopeptidases; Xanthomatosis, Cerebrotendinous

Cerebrotendinous xanthomatosis (CTX) and Lathosterolosis represent two treatable inherited disorders of cholesterol metabolism that are characterized by the accumulation of cholestanol and lathosterol, respectively. The age of the patients suspected of having these disorders is highly variable due to the very different phenotypes. The early diagnosis of these disorders is important because specific therapeutic treatment could prevent the disease progression. The biochemical diagnosis of these defects is generally performed analyzing the sterol profile. Since age-related levels of these sterols are lacking, this study aims to determine a preliminary comparison of plasma levels of cholestanol and lathosterol among Italian unaffected newborns, children and healthy adults.. The sterols were extracted from 130 plasma samples (24 newborns, 33 children and 73 adults) by a liquid-liquid separation method and quantified by gas chromatography coupled with a flame ionization detector.. Cholesterol, cholestanol and lathosterol levels together with the cholestanol/cholesterol and lathosterol/cholesterol ratios are statistically different among the three groups. Cholesterol levels progressively increased from newborns to children and to adults, whereas cholestanol/cholesterol and cholestanol/lathosterol ratios progressively decreased from newborns to children and to adults. Lathosterol levels were higher in adults than in both newborns and children. In the total population a positive correlation was observed between cholesterol levels and both cholestanol (correlation coefficient = 0.290, p = 0.001) and lathosterol levels (correlation coefficient = 0.353, p <  0.0001).. Although this study can only be considered an explorative experience due to the low number of analyzed samples, we revealed several differences of plasma cholestanol and lathosterol levels and their ratios to cholesterol levels among newborns, children and adults. These evidences indicate the need of age-related reference values of cholestanol and lathosterol concentrations, including also newborns and children.

Topics: Adult; Age Factors; Child; Cholestanol; Cholesterol; Disease Progression; Early Diagnosis; Female; Humans; Infant, Newborn; Male; Oxidoreductases Acting on CH-CH Group Donors; Phytosterols; Steroid Metabolism, Inborn Errors; Xanthomatosis, Cerebrotendinous

Topics: Cholestanol; Cholesterol; Gas Chromatography-Mass Spectrometry; Humans; Hypercholesterolemia; Intestinal Diseases; Limit of Detection; Lipid Metabolism, Inborn Errors; Phytosterols; Reference Standards; Sitosterols; Xanthomatosis, Cerebrotendinous

Cholesterol precursors and plant sterols have considerable potential as plasma biomarkers in several disorders of sterol metabolism and intestinal sterol absorption. Oxysterols are associated with atherogenesis, neurodegeneration, and inflammation. We developed a GC-MS method for the simultaneous analysis of these species in human plasma, including 24-, 25-, 27-hydroxycholesterol; 7-ketocholesterol; lanosterol; lathosterol; 7-dehydrocholesterol; desmosterol; stigmasterol; sitosterol; and campesterol.. Sterols were hydrolyzed with ethanolic potassium hydroxide solution, extracted by liquid/liquid extraction with n-hexane, and derivatized with N-methyl-N-trimethylsilyl-trifluoracetamide. Positive chemical ionization with ammonia, as reagent gas, was applied to generate high abundant precursor ions.. The definition of highly sensitive precursor/product ion transitions, especially for coeluting substances, allowed fast gas chromatography run times of under 8.5 min. Using the multiple reaction monitoring mode, detection limits in the picogram per milliliter range could be achieved for most compounds. The method was validated for precision and recovery. Intraassay and interassay CVs were mostly <15% for serum and plasma samples. The recoveries of supplemented plasma samples in different concentrations were 88%-117%. The method was applied to stratification of patients with disorders in cholesterol biosynthesis and/or cholesterol absorption in hypercholesterolemia. The method revealed associations of sterol species with thyroid dysfunction and type 2 diabetes.. This method allows high-throughput sterol profiling in various diseases.

Topics: Cholesterol; Gas Chromatography-Mass Spectrometry; Humans; Hypercholesterolemia; Hyperthyroidism; Hypothyroidism; Niemann-Pick Disease, Type C; Phytosterols; Plasma; Sterols; Tandem Mass Spectrometry; Tangier Disease; Xanthomatosis, Cerebrotendinous