To clarify the relationship between the expression of atherogenic small, dense low-density lipoprotein (SDLDL) and underlying lipid metabolic abnormalities, the prevalence of SDLDL in relation to the serum lipid phenotype was analyzed in 229 children. The LDL particle size was measured using gradient gel electrophoresis, and a particle size of less than 25.5 nm was considered to represent SDLDL. The overall prevalence of SDLDL in the sample population was 8.2% (19/229; 11/117 for boys and 8/112 for girls). Hyperlipidemia phenotype IIb (elevated concentrations of both triglyceride [TG] and total cholesterol [TC]) was strongly associated with SDLDL in 83% (5/6) of the subjects. An elevated TG concentration (phenotype IV) was associated with SDLDL in 55% (10/18) of the subjects. The association between hyperlipidemia phenotype IIa (elevated TC but a normal TG concentration) and SDLDL was quite low (2%; 1/56), but SDLDL was detected in 5% (8/155) of the subjects who presented with normolipidemia. Therefore, these findings suggest that the expression of SDLDL is largely related to lipid abnormalities characterized by phenotype IIb or IV, the underlying metabolic abnormality of which is suspected to be insulin resistance; however, an additional mechanism for the formation of SDLDL that functions independently of plasma lipid abnormalities also seems to exist.

Lipids and fatty acids are crucial nutrients for growth and development during entire childhood from infants to adolescents, although high cholesterol and triglyceride levels are risk factors for cardiovascular diseases developed in adulthood. The concept of developmental origin of health and disease （DOHaD） is well established, and undernutrition in utero following a mismatch between pre- and postnatal environments permanently changes the body composition, function and metabolism that lead to atherosclerosis and metabolic syndrome in later life. Our investigations and research were carried out mainly in clinical and public health settings, focusing on subcutaneous adipose tissue development during infancy and its relating metabolic and hormonal factors. Based on our clinical data and clinical experiences, we reviewed here the relationship between intrauterine undernutrition and serum lipid/lipoprotein/fatty acid profile, subcutaneous adipose tissue development in light for gestational date （LFD） infants, children with metabolic syndrome born LFD, and the fluctuation of LDL-C levels observed in children/adolescents with heterozygous familial hypercholesterolemia. We would like to provide some implications for future studies regarding lipids/fatty acids metabolism and adipose tissue development during fetal and neonatal periods, which may link to metabolic syndrome and atherosclerosis in later life.