• Journal of Yeungnam Medical Science
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• v.37 no.4
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• pp.332-336
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• 2020

Homozygous mutations in NUDT15 R139C are known as the major factor associated with thiopurine-induced early leukopenia, particularly in Asian patients. Therefore, NUDT15 genotyping is currently recommended before thiopurine treatment to identify patients who are NUDT15 poor metabolizers and consider the use of an alternative immunomodulatory therapy. We report a case of a 12-year-old Korean girl with Crohn's disease (CD), in whom thiopurine-induced leukopenia was prevented by initiation of azathioprine (AZA) therapy at a low dose (0.5 mg/kg/day) and early detection of significant hair loss and white blood cell (WBC) count decrease at 17 days from the start of AZA treatment. The WBC count dropped from 8,970/μL to 3,370/μL in 2 weeks, and AZA treatment was stopped because of concerns of potential leukopenia in the near future. Her WBC count recovered to 5,120/μL after 3 weeks. Gene analysis later revealed that she had a homozygous mutation in NUDT15 R139C, resulting in a poor metabolizing activity of NUDT15. In situations when NUDT15 genotyping is unavailable, initiation of AZA therapy at 0.5 mg/kg/day with close observation of hair loss and WBC counts within 2 weeks may be an alternative way to prevent thiopurine-induced early leukopenia in Asian children with CD.

• BMB Reports
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• v.41 no.9
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• pp.651-656
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• 2008

A mouse with cataract, Kec, was generated from N-ethyl-N-nitrosourea (ENU) mutagenesis. Cataract in the Kec mouse was observable at about 5 weeks after birth and this gradually progressed to become completely opaque by 12 weeks. Dissection microscopy revealed that vacuoles with a radial or irregular shape were located primarily in the cortex of the posterior and equatorial regions of the lens. At the late stage, the lens structure was distorted, but not ruptured. This cataract phenotype was inherited in an autosomal recessive manner. We performed a genetic linkage analysis using 133 mutant and 67 normal mice produced by mating Kec mutant (BALB/c) and F1 (C57BL/6 $\times$ Kec) mice. The Kec locus was mapped to the 3 cM region encompassed by D14Mit34 and D14Mit69. In addition we excluded coding sequences of 9 genes including Rcbtb2, P2ry5, Itm2b, Med4, Nudt15, Esd, Lcp1, Slc25a30, and 2810032E02Rik as the candidate gene that causes cataract in the Kec mouse.