|Ahead of print publication
Alopecia as the first manifestation of azathioprine myelosuppression in a genetically predisposed patient
Debashish Mishra, Shefali Khanna Sharma, Aman Sharma, Sanjay Jain, Varun Dhir
Department of Internal Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, India
Department of Internal Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh - 160 012
Source of Support: None, Conflict of Interest: None
Azathioprine, an analog of mercaptopurine, is used for various inflammatory/autoimmune diseases in diverse fields such as rheumatology, ophthalmology, gastroenterology, and neurology. One of the dreaded side effects of this drug is myelosuppression, which can be either dose related or “idiosyncratic.” The latter group often manifests with sudden cytopenias and is often secondary to a genetic predisposition. Mutations in the genes thiopurine S-methyltransferase (TPMT) and nucleoside diphosphate-linked moiety X-type motif 15 (NUDT15) have been identified to predispose to severe myelosuppression with azathioprine. An important clinical clue that can precede the onset of myelosuppression is alopecia. Here, we describe the case of a young lady treated with azathioprine, who developed alopecia (progressing to alopecia totalis), which was followed by severe cytopenia – both of which recovered on stopping the drug. On genetic analysis, she was found to be homozygous for mutation in NUDT15 (C415T) but was negative for mutation in TPMT. We review various other cases reporting alopecia as a marker of azathioprine-induced myelosuppression and the genetic mutations described.
Keywords: Alopecia, Azathioprine, cytopenia, mercaptopurine, myelosuppression
|How to cite this URL:|
Mishra D, Sharma SK, Sharma A, Jain S, Dhir V. Alopecia as the first manifestation of azathioprine myelosuppression in a genetically predisposed patient. Indian J Rheumatol [Epub ahead of print] [cited 2019 Jan 18]. Available from: http://www.indianjrheumatol.com/preprintarticle.asp?id=246309
| Introduction|| |
Azathioprine is an immunosuppressant purine analog and prodrug of mercaptopurine. It is used in a variety of rheumatological and immunological disorders such as systemic lupus erythematosus, Behcet's syndrome, inflammatory bowel disease, and inflammatory eye diseases. A dreaded complication that requires close monitoring is myelosuppression manifesting as cytopenias. Apart from mild myelosuppression (often dose related), an “idiosyncratic” potentially fatal severe myelosuppression can also occur. This previously called “idiosyncratic” adverse effect has been found to be related to genetic variations.
Indeed, it is well known that individuals with thiopurine S-methyltransferase (TPMT) deficiency, due to mutations in the TPMT gene, are predisposed to develop bone marrow suppression on azathioprine. However, even patients with normal TPMT genotype have been reported to develop severe toxicity on azathioprine, suggesting other unrecognized genetic associations. One such association was reported by Yang et al. in 2014, when they found that the presence of nucleoside diphosphate-linked moiety X-type motif 15 (NUDT15) variant (gene ID: 55270; rs116855232; C415T; encoding p. Arg139Cys) in Korean patients was associated with myelosuppression. However, current recommendations only suggest TPMT genotyping before initiation of azathioprine., In addition, it is recommended to monitor blood counts weekly (and later biweekly) in all patients till 8–12 weeks.,
Importantly, physicians need to recognize early clinical clues to the impending development of myelotoxicity. One important clue that may be useful is the occurrence of alopecia. This report describes the case of a young lady who developed alopecia (progressing to totalis) before bone marrow suppression and on genotyping was found to be NUDT15 mutation positive but TPMT mutation negative. We subsequently searched the literature and found several such cases, in which alopecia occurred concurrently or before cytopenias due to azathioprine; some of these have studied mutations in TPMT and NUDT15.
| Case Report|| |
A 35-year-old female was evaluated for headache and bilateral decreased vision for 15 days, under the ophthalmological services. Her visual acuity was limited to perception of hand movements on the right side and finger counting up to 2 m on the left side. She underwent fluorescein angiography and optical coherence tomography scan that revealed features suggestive of bilateral Vogt–Koyanagi–Harada syndrome (VKH syndrome). She was given three pulses of methylprednisolone (1 g), followed by oral prednisolone at a dose of 1 mg/kg/day. Her routine hemogram was normal. As a steroid-sparing agent, azathioprine was started on a daily dose of 50 mg. After a week, her azathioprine dose was increased to 100 mg (2 mg/kg/day). Two weeks after the initiation of azathioprine, she complained of increased hair loss; however, her hemogram was normal and she was continued on azathioprine at the same dose. At the 6th week, she returned with patchy hair loss, loss of eyebrows, fever, and productive cough. Investigations revealed pancytopenia (hemoglobin 8.5 g/dl, total leukocyte count 600/μL, and platelet count of 78,000/μl) with high erythrocyte sedimentation rate and C-reactive protein (135 mm in the 1st h and 290 mg/l, respectively). Azathioprine was stopped and broad-spectrum antimicrobial drugs were started, with which her counts gradually improved [Figure 1]. Skin biopsy from the site of hair loss revealed features suggestive of alopecia areata with increased number of telogen hair and follicular stella. Over the next 1 month, she developed complete balding (alopecia totalis) [Figure 2]. One month later, her blood counts had normalized except anemia – hemoglobin 8.2 g/dl, total leukocyte count 4400/μl, and platelets count of 163,000/μl. TPMT and NUDT15 mutation studies were performed elsewhere (see acknowledgments). Amplification refractory mutation system–polymerase chain reaction was employed for NUDT15 genetic variant and TPMT *2 variant genotyping, whereas restriction fragment length polymorphism technique was employed for genotyping of TPMT *3A, *3B, and *3C genetic variants. Her TPMT genotype was wild type, but she had homozygous NUDT15 mutation (C415T). She was subsequently started on methotrexate (weekly) as a steroid-sparing agent. On 2-month follow-up, she had complete normalization of her hemogram with regrowth of hair [Figure 3].
|Figure 1: Graphical representation of hemogram profile of the index case – during and after stopping azathioprine|
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|Figure 3: Reversal of alopecia after stopping azathioprine (on 2-month-follow up)|
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| Discussion|| |
We report a case of azathioprine-induced alopecia (progressing to alopecia totalis) as a harbinger of severe myelosuppression in a patient who was genetically predisposed. We searched the literature for alopecia as an adverse effect of azathioprine and its association with myelosuppression and genetic studies. The relevant cases have been listed in [Table 1]. Similar to our case, Kim et al. also described a gap of 2 weeks between the onset of alopecia and pancytopenia. Another case described simultaneous occurrence of alopecia and pancytopenia within 2 weeks of starting azathioprine. However, unlike NUDT15 mutant homozygous state in our patient, they did not report the NUDT15 variant in their cases. Apart from these, some reports of the isolated alopecia totalis without myelosuppression due to azathioprine also exist in the literature.,
|Table 1: Various case reports/studies citing hair loss/cytopenia after azathioprine treatment|
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Apart from these case reports, alopecia with myelosuppression has been reported from larger studies in patients on azathioprine, many of which reported genetic associations. In a study of lupus patients from China, five patients who developed alopecia and myelosuppression were reported. Three were heterozygous for TPMT *3C and two were homozygous for this mutation. Interestingly, the authors of that paper have also speculated that alopecia could be a marker of myelotoxicity of azathioprine. Similarly, there have been studies looking at the NUDT15 C415T mutation since its description 4 years ago. In a study from India, NUDT15 genetic variation was found in 9 out of 69 patients. The one homozygous patient (NUDT15*TT) developed pancytopenia and severe hair loss mentioned in [Table 1]. Among the eight heterozygous patients (NUDT15*CT), five developed cytopenias and one developed alopecia. In a series from Korea, all five NUDT15 TT homozygous patients developed early severe leukopenia and alopecia. The authors reported a strong association of the NUDT15 mutation with early leukopenia (odds ratio of 107.6) and severe alopecia (odds ratio of 77.2).
TPMT enzyme is encoded by TPMT gene on chromosome 6p22.3, which exists as normal wild type (TPMT *1/*1) or multiple variant alleles. Four of the variant alleles (TPMT *2, *3A, *3B, *3C) are responsible for <95% of mutations and variable levels of enzyme activity. In India, the prevalence of TPMT mutations has been reported to vary from 1.2% to 10% (heterozygous), whereas <1% have been reported to carry homozygous mutations.,, A study conducted by Garg et al. among 176 Indian patients with various autoimmune disorders who were on azathioprine and developed myelosuppression found a low prevalence of TPMT mutation (1.7%). A study from South India by Murugesan et al. reported the prevalence of TPMT mutations to be 2.8%, with TPMT *1/*3C being the predominant alleles.
As alluded previously, the NUDT15 variant (gene ID: 55270; rs116855232; C415T; encoding p. Arg139Cys) has recently been described to be associated with myelosuppression (initially in Korean patients). In a study by Shah et al. in Indians, NUDT15 variant was present in 19.4%. Interestingly, all those who developed leukopenia on thiopurine treatment had NUDT15 variant in that study. Although larger studies need to be carried out, NUDT15 variant testing seems to be at least as important as TPMT testing in Indians.
The common mechanism driving the toxicities of alopecia and myelosuppression could be cell death – hematopoietic precursor and root cells in the hair bulb. This could be due to the accumulation of thiopurine toxic metabolites, metabolism of which depends on two genetically influenced enzymes – TPMT- and NUDT15-encoded Nudix hydrolases [Figure 4].
|Figure 4: Role of thiopurine S-methyltransferase and nucleoside diphosphate-linked moiety X-type motif 15-encoded enzyme in azathioprine metabolism|
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To conclude, this case serves to highlight the importance of a simple clinical clue such as alopecia that can be a harbinger of severe myelosuppression in patients on azathioprine. Further, it emphasizes the need to look for NUDT15 mutation (apart from TPMT) in these patients.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed
The authors thank Dr. Tester F Ashavaid, Director (laboratory research) and consultant biochemist at the P.D. Hinduja Hospital & Research Center, Mumbai, for her assistance in processing the sample for TPMT genotyping and NUDT15 mutation analysis.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]