Background and aims: In two Japanese infants with neonatal cholestasis, 3-oxo-Δ4-steroid 5β-reductase deficiency was diagnosed based on mutations of the SRD5B1 gene. Unusual bile acids such as elevated 3-oxo-Δ4 bile acids were detected in their serum and urine by gas chromatography–mass spectrometry. We studied effects of oral chenodeoxycholic acid treatment.
Patients and methods: SRD5B1 gene analysis used peripheral lymphocyte genomic DNA. Diagnosis and treatment of these two patients were investigated retrospectively and prospectively investigated.
Results: With respect to SRD5B1, one patient was heterozygous (R266Q, a novel mutation) while the other was a compound heterozygote (G223E/R261C). Chenodeoxycholic acid treatment was effective in improving liver function and decreasing unusual bile acids such as 7α-hydroxy- and 7α,12α-dihydroxy-3-oxo-4-cholen-24-oic acids in serum and urine.
Conclusion: Primary bile acid treatment using chenodeoxycholic acid was effective for these patients treated in early infancy before the late stage of chronic cholestatic liver dysfunction.

Objective To establish a method of HPLC-ELSD method for the determination of the pig powder hyodeoxycholic and chenodeoxycholic acid simultaneous determination. Methods Wa-ters Symmetry C18 (4.6 mm × 150 mm, 5μm) column, methanol-0.2% formic acid (80:20) as the mobile phase, flow rate: 1.0 mL · min ^ -1; column temperature: 40 ℃; the detector was ELSD, drift tube temperature: 85 ℃, high purity nitrogen carrier gas flow rate: 2.0 L · min ^ -1. 

Results: hyodeoxycholic in 0.5192μg ~ 5.1920μg showed a good linear relationship (r = 0.999 4), the average recovery was 97.5%, RSD = 2.3%; CDCA in 0.5012μg ~ 5.0120μg the range was a good linear relationship (r = 0.999 8), the average recovery was 96.0%, RSD = 1.6%. Conclusion The method is simple, accurate, sensitive and can be used for quality control of the pig powder.