Abstract
We identified a Yi Chinese female patient from an ethnic minority group with methazolamide-induced toxic epidermal necrolysis. Genotyping revealed that she and her immediate family members carried the HLA-C*01:02 haplotypes, known to be associated with methazolamide-induced toxic epidermal necrolysis.
Keywords: Eye, Dermatological, Glaucoma, Unwanted effects / adverse reactions
Background
Methazolamide is a sulfonamide carbonic anhydrase inhibitor and a member of the sulfa drug family. It inhibits carbonic anhydrase in the ciliary body and reduces aqueous humour production, thereby reducing intraocular pressure in patients with glaucoma. Maren et al and Stone et al first studied low-dose methazolamide treatment of glaucoma; it was used clinically in the early 1976s.1 2 However, as a sulfa drug, it can also cause skin reactions and even severe rashes, including Stevens-Johnson syndrome or toxic epidermal necrolysis.3–5
Patients harbouring HLA-B*59:01 or HLA-B*59:01–C*01:02 haplotypes are at increased risk of methazolamide-induced Stevens-Johnson syndrome/toxic epidermal necrolysis.6 This finding has been reported in Asian patients, with no similar reports in Caucasians.6 7
In this study, a Yi Chinese patient with methazolamide-induced toxic epidermal necrolysis and her immediate family members were subjected to high-throughput genotyping to explore the genetic cause of adverse drug reactions (ADRs) to methazolamide in order to ensure the safety of clinical medication. We found a strong association between HLA-C*01:02 and methazolamide-induced Stevens-Johnson syndrome/toxic epidermal necrolysis in the Yi Chinese population for the first time.
Case presentation
A woman in her 50s from Yi Chinese ancestry was admitted to our institute. She was administered oral methazolamide (25 mg two times per day) orally to treat secondary glaucoma; we followed up on her and her six immediate family members. Informed consent was obtained from all individuals (patient and the relatives), after explaining the nature of the study. The intraocular pressure of the patient returned to the normal level after 14 days of treatment with methazolamide, and the medication was stopped. However, rash started to appear 3 days later.
Investigations
The patient had no recorded remarkable medical history and no history of ADRs. After completion of the treatment for secondary glaucoma, the patient was in good health. However, erythema and tingling appeared on the extremities 3 days after the discontinuation of methazolamide. They then spread to the trunk, face, neck and whole body; blisters and bullae appeared and tended to coalesce (figure 1A). Subsequently, the patient developed fatigue, a fever of 38.5℃, extensive skin peeling all over the body exceeding 80% of the body surface area and positive Nikolsky’s signs. Mucosal erosions included lips, mouth and genitals, but the ocular mucosa was not damaged (figure 1B). Auxiliary examination: CT of both lungs suggested pneumonia. Blood test prompts: the numbers of white blood cells, neutrophils and lymphocytes were reduced and that of platelets increased. Serum urea, bicarbonate, and blood sugar levels and heart rate were normal. The patient had no history of malignancy. According to the clinical manifestations, the patient was diagnosed to have toxic epidermal necrolysis. A severity-of-illness score for toxic epidermal necrolysis of 2 was recorded. The patient was administered methylprednisolone, gamma-globulin, moxifloxacin, and symptomatic treatment and provided whole body skin care. After 26 days of treatment, her condition improved; the skin lesions were dry, crusted and partly covered with scales; mucosal lesions on the lips and genitals healed; and the tingling sensation was significantly reduced (figure 1C).
Figure 1.
A woman in her 50s from Yi Chinese ancestry (Chen drew the figure). (A) Day 8 of disease onset in the patient. Red erosions on the lip mucosa with dark red scabs, erythema and papules all over the body were observed. A part of the skin lesions had fused into pieces, and blisters and bullae were observed. (B) Day 10 of disease onset. Multiple areas of skin on the face, neck, trunk and limbs had peeled off; a new red wound was observed in the peeled area. (C) Day 33 of disease onset. The skin lesions all over the body were dry, crusted and partially covered with scales.
Shortcomings of the report: because her condition progressed rapidly and the skin peeling area was extensive throughout the body, the patient could not bear such a severe condition and refused to undergo skin pathological biopsy.
Differential diagnosis
The patient was admitted to our hospital for surgery for a traumatic cataract in the right eye with lens detachment. Intraocular pressure of the patient’s right eye had increased to 35.5 mm Hg, whereas that of the left eye was normal. The rash appeared 17 days after initiation of the medication. Therefore, it was critical to identify the actual drug causing ADRs. The patient was administered oral methazolamide tablets 25 mg two times per day, intravenous infusion of 20% mannitol 250 mL once a day and levofloxacin eye drops to the right eye. After the operation, the intraocular pressure of the right eye was still high, up to 40.2 mm Hg. She continued to receive oral methazolamide tablets 25 mg two times per day for a total of 14 days and intravenous infusion of 20% mannitol 250 mL once a day for a total of 2 days. An intravenous drip of cefathiamidine 2 g three times a day to prevent infection was also administered for 3 days. Levofloxacin eye drops and prednisone acetate eye drops were locally administered to the right eye for a total of 14 days. After admission, the topical ophthalmic drugs levofloxacin ophthalmic solution and prednisolone acetate ophthalmic solution showed no local adverse reactions within 14 days, and the possibility of topical ophthalmic use was ruled out. Systemic cefathiamidine medication can cause adverse skin reactions, but the patient had used cephalosporin antibiotics in the past, and no ADRs had occurred. Cefathiamidine is used only for 3 days to prevent infection, and the interval is 13 days when rash occurs. Its half-life in the body is 12 hours. After five half-lives (60 hours), the drug is almost completely eliminated from the body. The longest time for delayed-type ADRs after discontinuing cefathiamidine is 9.5 hours; therefore, Stevens-Johnson syndrome/toxic epidermal necrolysis caused by cefathiamidine was not considered. Mannitol also causes adverse skin reactions. The patient used it for 2 days, and the rash occurred 14 days apart. Its half-life in the body is 100 min, and 80% of mannitol can be eliminated in 3 hours. Delayed ADRs caused by mannitol have not been reported. Therefore, the possibility of mannitol causing Stevens-Johnson syndrome/toxic epidermal necrolysis in this case was extremely low. The half-life of methazolamide in the body is 14 hours, and residual methazolamide may persist in the body after 3 days of its discontinuation. The patient developed cutaneous ADRs on the third day of discontinuation of methazolamide. She had no history of sulfonamide use and developed toxic epidermal necrolysis 17 days after oral administration of methazolamide, consistent with an incubation period of 1–58 days (mean duration 16.5 days) for ADRs to methazolamide.
Based on the above analysis, the patient was diagnosed with toxic epidermal necrolysis caused by methazolamide.
Treatment
The patient was administered intravenous methylprednisolone 300 mg (equivalent to prednisone 7.5 mg/kg/day) for 1 day, and the dose was reduced to 200 mg for 2 days and tapered gradually over 26 days. Gamma-globulin was administered intravenously at 0.3 g/kg/day for 22 days, and moxifloxacin was administered intravenously for anti-infection and systemic support treatment. Simultaneously, compound polymyxin B ointment, recombinant human basic fibroblast growth factor for external use, dexamethasone boric acid cream and skin burn care were used externally. After 26 days of treatment, the patient had no fever, and the erosion surface of the skin had gradually dried. During the dose reduction of methylprednisolone, no new skin damage occurred, and the patient recovered and was discharged from the hospital (figure 1).
Outcome and follow-up
Genotyping was performed on the Illumina Infinium Chinese Genotyping Array BeadChip: Illumina WeGene V3 Arrays, using the Illumina iScan System according to the manufacturer’s instructions. The human leucocyte antigen (HLA) alleles were imputed using reference data of a Han Chinese major histocompatibility complex (MHC) database, which contains classic types of HLA-A, HLA-B and HLA-C from the sequenced 5 Mb MHC region in 20 635 individuals of Han Chinese ancestry. We encoded all variants in the reference panel as biallelic markers, which facilitated the application of Eagle/Minimac4 imputation (using default parameters).
Through high-throughput genotyping, we found that the patient and family members 2, 4 and 5 carried the HLA-A*24:02–C*01:02 haplotype; family members 1 and 6 carried the HLA-C*01:02 haplotype, and family member 3 carried the HLA-A*24:02 haplotype (table 1).
Table 1.
Genotyping results
| Subject | Age*/sex | Haplotype detection result | ||
| HLA-A | HLA-B | HLA-C | ||
| Patient | 50–60/F | *11:01/*24:02 | *15:25/*55:12 | *01:02/*04:03 |
| Family member 1 | 70–80/F | *11:01/*11:01 | *39:01/*55:12 | *01:02/*07:02 |
| Family member 2 | 30–40/F | *11:01/*24:02 | *15:25/*56:01 | *01:02/*04:03 |
| Family member 3 | 30–40/F | *24:02/*24:02 | *15:25/*15:25 | *04:03/*04:01 |
| Family member 4 | 10–20/F | *02:07/*24:02 | *46:01/*15:25 | *01:02/*04:03 |
| Family member 5 | 0–10/M | *02:07/*24:02 | *46:01/*15:25 | *01:02/*04:03 |
| Family member 6 | 0–10/M | *11:01/*11:01 | *46:01/*55:12 | *01:02/*01:02 |
*Age in years.
We also found that the HLA-A*24:02 and HLA-C*01:02 haplotypes were hereditary (figure 2).
Figure 2.
Family pedigree (Chen drew the figure).
This family carried the HLA-A*24:02 and HLA-C*01:02 haplotypes. According to Mendel’s law of inheritance and the detection result of family member 1 (the mother of the patient), it was speculated that the patient inherited the HLA-A*11:01–B*55:12–C*01:02 haplotype from her mother, whereas HLA-A*24:02–B*15:25–C*04:03 was inherited from her deceased father, even though we were unable to obtain a sample from him. Furthermore, the patient passed on this inherited HLA-B*15:25 to her two daughters. Her deceased husband had at least one A*24:02 positive and could have had two HLA-C genotypes (C*04:03/C*04:01 or C*01:02/C*04:01). It was concluded that the patient transmitted HLA-A*24:02–B*15:25–C*04:03 to ctrl3, whereas her husband contributed HLA-A*24:02–B*15:25–C*04:01. Considering the multiple genotypes of the husband and the recombination of the genome, four probable hereditary patterns for family member 2 (table 2) were suggested.
Table 2.
Four probable hereditary patterns for family member 2
| Pattern | Person | Genotype | Transmission to ctrl2 | Transmission to ctrl3 | ||
| HLA-A | HLA-C | HLA-A | HLA-C | |||
| 1 | Patient | A*11:01/A*24:02 C*01:02/C*04:03 |
A*11:01 | C*01:02 | A*24:02 | C*04:03 |
| Husband | A*24:02/? C*04:03/C*04:01 |
A*24:02 | C*04:03 | A*24:02 | C*04:01 | |
| 2 | Patient | A*11:01/A*24:02 C*01:02/C*04:03 |
A*24:02 | C*04:03 | A*24:02 | C*04:03 |
| Husband | A*11:01/A*24:02 C*01:02/C*04:01 |
A*11:01 | C*01:02 | A*24:02 | C*04:01 | |
| 3 | Patient | A*11:01/A*24:02 C*01:02/C*04:03 |
A*11:01 | C*04:03 | A*24:02 | C*04:03 |
| Husband | A*24:02/? C*01:02/C*04:01 |
A*24:02 | C*01:02 | A*24:02 | C*04:01 | |
| 4 | Patient | A*11:01/A*24:02 C*01:02/C*04:03 |
A*24:02 | C*01:02 | A*24:02 | C*04:03 |
| Husband | A*11:01/A*24:02 C*04:03/C*04:01 |
A*11:01 | C*04:03 | A*24:02 | C*04:01 | |
Following the pedigree pattern, family member 2 passed on the inherited HLA-C*01:02 to her son but not HLA-A*24:02. On the contrary, family member 3 married a person who is a carrier of HLA-C*01:02. This couple then transmitted the HLA-A*24:02–C*01:02 to their offspring. In humans, the MHC is the HLA on the short arm of chromosome 6. The HLA region is classified into three parts, where HLA-A, HLA-B and HLA-C are in the class I region. HLA-A is near the telomere, HLA-B is relatively close to the centromere and HLA-C is between these genes but closer to HLA-B. HLA-B*59:01–C*01:02 gene loci in the HLA region may be associated with this ADR, but HLA-B*59:01 was not identified in our analysis (figure 3).
Figure 3.
Locations of HLA-A, HLA-B and HLA-C on chromosome 6 (Chen drew the figure). For humans, the major histocompatibility complex is the human leucocyte antigen (HLA), which is located on the short arm of chromosome 6. The HLA region could be divided into three parts: HLA-A, HLA-B and HLA-C are in the class I region. HLA-A is near the telomere, whereas HLA-B is relatively close to the centromere, and C is between A and B, closer to B. In addition, many other gene loci reported in HLA were not detected in our analysis.
Discussion
Methazolamide is commonly used to reduce intraocular pressure associated with glaucoma and other ocular disorders. ADRs to this drug are associated with the HLA-B*59:01 or HLA-B*59:01–C*01:02 haplotypes, leading to Stevens-Johnson syndrome/toxic epidermal necrolysis, and the frequency of patients carrying HLA-C*01:02 is high (OR: 22.1).7 8 In this study, the patient suffered from methazolamide-associated toxic epidermal necrolysis. After the patient recovered, we collected saliva samples from her and her immediate family members for genotyping to identify the causative genes and determine their pedigree (family member 1 was the patient’s mother; family members 2 and 3 were the patient’s daughters; family members 4, 5 and 6 were the patient’s grandchildren).
We collected seven saliva samples and detected three different HLA haplotypes. The patient and her immediate family members carried the HLA-A*24:02 haplotype, the HLA-C*01:02 haplotype or both; whereas the HLA-B*59:01 haplotype was absent. Kim et al reported that the HLA-A*24:02 and HLA-C*01:02 haplotypes are closely related to the HLA-B*59:01 haplotypes according to linkage disequilibrium studies. In patients with Stevens-Johnson syndrome/toxic epidermal necrolysis induced by methazolamide, the incidence of HLA-C*01:02 is increased significantly, and the frequency of patients carrying HLA-B*59:01, HLA-C*01:02 and HLA-A*24:02 haplotypes simultaneously is significantly higher than that in the general Korean population.8 However, the HLA-A*24:02 haplotype is present at a relatively higher ratio in the Han Chinese population (31.45%), considering that HLA-A*24:02 might have little effect on the Stevens-Johnson syndrome/toxic epidermal necrolysis induced by methazolamide.7
Previous studies have been mostly conducted in Korean and Japanese populations,9 10 with a few studies on the Han Chinese population.7 The HLA-B59 genotype may be the leading cause of Stevens-Johnson syndrome/toxic epidermal necrolysis in Asians. The racial/ethnic differences in terms of HLA genotypes and ADRs are mainly determined by the risk frequency of HLA alleles in each ethnic group.7 HLA-B*59:01–C*01:02 haplotype frequency is 1.60% and 1.70% in the Japanese and Korean population, respectively.3 Currently, no reference data on the risk frequency of HLA alleles are available for either the Han Chinese population or the Yi Chinese population.
Genetic factors play a key role in the primary pathogenic mechanism of drug ADRs, and it is necessary to study familial factors.10 This may help prevent serious ADRs in family members when taking the same drugs. We predict a relationship between HLA genotypes and methazolamide-induced Stevens-Johnson syndrome/toxic epidermal necrolysis in the Yi Chinese population based on this case. Family members 2, 4 and 5 with both HLA-A*24:02 and HLA-C*01:02 haplotypes (as in the primary patient) may have a higher probability of methazolamide-induced Stevens-Johnson syndrome/toxic epidermal necrolysis; however, the presence of the HLA-C*01:02 haplotype alone in family members 1 and 6 also poses the risk of methazolamide-induced Stevens-Johnson syndrome/toxic epidermal necrolysis (table 2).
Methazolamide-induced Stevens-Johnson syndrome/toxic epidermal necrolysis is a very rare disease. A limitation of this study is that we identified only one Yi Chinese family cluster with these haplotypes, and hence the small-study effect is unavoidable. Moreover, the family pedigree is not very extensive because of the limited number of available family members. Nonetheless, our study shows the first Yi Chinese patient who developed ADR to methazolamide, and it is also the first report on the use of high-resolution HLA genotyping for a patient with this ADR and their immediate family.
Patient’s perspective.
When I first became ill and found erythema on my body, I neglected it. Progressively, it became very serious, and I was worried about my life. When the doctor told us that the drug caused it, I felt helpless and found it unfair. Why was it me? However, there was no alternative. Thanks to the doctor, after 26 days of tormenting treatment, my condition finally improved. I am also happy to have contributed to the identification of the genetic basis of the disease, which may help prevent my family members from suffering this disease in the future.
Learning points.
This study showed a strong association between HLA-C*01:02 and methazolamide-induced Stevens-Johnson syndrome/toxic epidermal necrolysis in a Yi Chinese population for the first time.
Methazolamide-induced Stevens-Johnson syndrome/toxic epidermal necrolysis is a very rare and serious fatal disease. During and after use, patients should be closely observed for adverse reactions such as rash. Adequate awareness, preventive management and effective treatment are essential for patient survival.
Patients with Stevens-Johnson syndrome/toxic epidermal necrolysis caused by methazolamide have a susceptibility gene, and their immediate family members are also likely to harbour this gene; therefore, special attention should be paid to the use of similar drugs (such as sulfonamides). If necessary, genetic screening of immediate family members before methazolamide use should be performed.
Doctors should conduct genetic testing on the patient’s immediate family members, and family members found to have the same positive gene should be informed that they cannot use drugs such as methazolamide throughout their lives, in order to avoid serious adverse drug reactions or even chance life-threatening reactions to similar drugs.
Acknowledgments
Funding from the National Natural Science Foundation of China (grant number: 82171026) is gratefully acknowledged.
Footnotes
Contributors: GQ performed all the experiments and analyses of the data. CZ and HX investigated the gene data. GQ and CZ helped with connecting with patient. GQ and CQ designed this project and wrote the manuscript. GQ and CQ were involved in the clinical management of the patient. GQ and CZ contributed equally to the work.
Funding: National Natural Science Foundation of China (82171026).
Case reports provide a valuable learning resource for the scientific community and can indicate areas of interest for future research. They should not be used in isolation to guide treatment choices or public health policy.
Competing interests: None declared.
Provenance and peer review: Not commissioned; externally peer reviewed.
Ethics statements
Patient consent for publication
Obtained.
Ethics approval
The study adhered to the tenets of the Declaration of Helsinki (approval number: 443 (2020)).
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