Measurement of 7-dehydrocholesterol and cholesterol in hair can be used in the diagnosis of Smith-Lemli-Opitz syndrome.

7-dehydrocholesterol (7-DHC) and cholesterol (CHOL) are biomarkers of Smith-Lemli-Opitz Syndrome (SLOS), a congenital autosomal recessive disorder characterized by elevated 7-DHC level in patients. Hair samples have been shown to have great diagnostic and research value, which has long been neglected in the SLOS field. In this study, we sought to investigate the feasibility of using hair for SLOS diagnosis. In the presence of antioxidants (2,6-ditert-butyl-4-methylphenol and triphenylphosphine), hair samples were completely pulverized and extracted by micro-pulverized extraction in alkaline solution or in n-hexane. After microwave-assisted derivatization with N,O-Bis(trimethylsilyl)trifluoroacetamide, the analytes were measured by GC-MS. We found that the limits of determination for 7-DHC and CHOL were 10 ng/mg and 8 ng/mg, respectively. In addition, good linearity was obtained in the range of 50-4000 ng/mg and 30-6000 ng/mg for 7-DHC and CHOL, respectively, which fully meets the requirement for SLOS diagnosis and related research. Finally, by applying the proposed method to real hair samples collected from 14 healthy infants and two suspected SLOS patients, we confirmed the feasibility of hair analysis as a diagnostic tool for SLOS. In conclusion, we present an optimized and validated analytical method for the simultaneous determination of two SLOS biomarkers using human hair.

A reliable tool for detecting 7-dehydrocholesterol and cholesterol in human plasma and its use in diagnosis of Smith-Lemli-Opitz syndrome.

BACKGROUND: Smith-Lemli-Opitz syndrome is a birth defect caused by the deficiency of 7-dehydrocholesterol reductase in cholesterol biosynthesis pathway, which leads to accumulation of 7-dehydrocholesterol and reduction of cholesterol in body fluids. To effectively diagnose Smith-Lemli-Opitz syndrome and monitor therapy, a reliable method for simultaneous detection of 7-dehydrocholesterol and cholesterol is needed. METHODS: In the presence of antioxidants (2,6-ditert-butyl-4-methylphenol and triphenylphosphine), 50 µL of human plasma were hydrolyzed at 70℃ for 40 min with 1 M potassium hydroxide in 90% ethanol, and then 7-dehydrocholesterol and cholesterol were extracted by 600 µL of n-hexane for three times. After microwave-assisted derivatization with 70 µL of N,O-bis(trimethylsilyl)trifluoroacetamide at 460 W for 3 min, the analytes were measured by gas chromatography-mass spectrometry. RESULTS: The limits of detection were 100 ng/mL for 7-dehydrocholesterol and 300 ng/mL for cholesterol. Good linearity was obtained in the range of 1-600 µg/mL for 7-dehydrocholesterol and 10-600 µg/mL for cholesterol, which completely covered the biochemical levels of Smith-Lemli-Opitz syndrome patients that have been reported. CONCLUSION: A time-saving and accurate gas chromatography with mass spectrometry based method was developed for the determination of 7-dehydrocholesterol and cholesterol in human plasma, which also serves as a useful tool for Smith-Lemli-Opitz syndrome diagnosis, treatment, and research.