J Med Genet 1998;35:255-257 255 Pancreatic exocrine dysfunction associated with mitochondrial tRNAIeu(UR) mutation J Med Genet: first published as 10.1136/jmg.35.3.255 on 1 March 1998. Downloaded from Hideki Onishi, Tokiji Hanihara, Naoya Sugiyama, Chiaki Kawanishi, Eizo Iseki, Yasuko Maruyama, Yoshiteru Yamada, Kenji Kosaka, Saburo Yagishita, Hisahiko Sekihara, Shinobu Satoh Abstract Family C. The proband (C-I) is a 55 year old We report on pancreatic exocrine dys- woman with a history ofDM from the age of 53 function in families that have the mito- years. Her son (C-II), aged 25, developed chondrial tRNAIAu(UR) gene mutation. stroke-like episodes and haemianopia at the These families exhibited maternally in- age of 21 and was diagnosed as having herited diabetes mellitus (DM) and an A MEIAS. He was further diagnosed as having to G substitution at nt 3243 of the DM at the age of 23. The clinical symptoms mitochondrial tRNAutu) gene (A3243G and molecular genetic analysis ofA-II and B-II mutation). Pancreatic necropsy samples have been described in previous reports.78 from one proband showed accumulation As a test of exocrine pancreatic function, we of degenerated mitochondria in pancre- performed a bentiromide test using benzoyl- atic acinar cells. Pancreatic exocrine dys- tyrosyl-p-aminobenzoic acid (Bz-Ty-PABA, function was recognised by a functional PFD oral, Eisai Co Ltd)9 on the probands and pancreatic study. This study indicates that their sons in families B and C, as they were the exocrine pancreatic dysfunction may be only ones who agreed to the test. The test was associated with the A3243G mutation. performed according to the manufacturer's (7Med Genet 1998;35:255-257) instructions. Results were expressed as per- centage recovery of PABA in urine (normal Keywords: mitochondrial DNA; pancreatic exocrine range=81.9±8.5% in non-diabetic subjects and dysfunction; bentiromide test 77±12.6% in diabetic patients).10" We could not perform the test on the proband in family A Many mitochondrial DNA (mtDNA) muta- (A-II) because of his poor condition. tions are associated with various diseases.' One Genomic DNA extraction, PCR amplifica- of the most common mutations involves an A tion, restriction enzyme analysis, sequencing, to G substitution at nt 3243 of the tRNAI'u'(R) and densitometric analysis were performed as of gene (A3243G mutation).2 Recent studies have previously described.8 Department http://jmg.bmj.com/ Psychiatry, Yokohama shown that there is a close association between The pathological findings of the pancreas of City University School the A3243G mutation and maternally inher- patient A-II at necropsy are as follows. The ofMedicine, 3-9 ited DM.' Multiorgan involvement has also pancreas showed no acinar atrophy or fibrosis. Fukuura, In the pancreatic acini, degenerative acinar Kanazawa-ku, been suggested.4 However, pancreatic exocrine Yokohama City, dysfunction has not been investigated, al- cells with pycnotic nuclei were found to be Kanagawa 236, Japan though it has been reported in patients with scattered or clustered. As determined by H Onishi mtDNA deletion.5 6Here, we report on pancre- electron microscopy, these cells had lost most T Hanihara atic exocrine dysfunction in families with the of the rough endoplasmic reticulum, Golgi on September 25, 2021 by guest. Protected copyright. N Sugiyama apparatus, and secretory granules, and were C Kawanishi A3243G mutation. E Iseki Clinical characteristics of the family mem- occupied by closely congregated vacuolar Y Maruyama bers are as follows (fig 1). mitochondria (fig 2). No dilatation of the ducts Y Yamada Family A. The proband (A-II), a 39 year old or liposis was present. The number ofislets was K Kosaka man, was diagnosed as having DM at the age of markedly decreased. 29 years. He developed stroke-like episodes Molecular genetic analysis of the five pa- Department of muta- Pathology, Kanagawa and was diagnosed with mitochondrial myopa- tients showed that they had an A3243G Rehabilitation Centre, thy, encephalopathy, lactic acidosis, and stroke- tion to different degrees. Densitometric analy- Japan like episodes (MELAS) at the age of 31 years. sis showed the percentage of mutant mtDNA S Yagishita He continued to experience stroke-like epi- in the white blood cells and the necropsy sam- sodes. In the later stages of the disease, he had ples ranged from 6% to 63% (fig 1). of Department at age A The five patients showed normal serum Internal Medicine, chronic diarrhoea. He died the of 39. Yokohama City necropsy was performed six hours after death. amylase and lipase levels. The bentiromide test University School of Family B. The proband (B-I) is a 52 year old indicated that three ofthe four patients showed Medicine, Japan woman with a history ofDM from the age of 50 a decreased percentage recovery of PABA, S Satoh years. The proband's son (B-II), aged 24 years, which in patients B-I, B-II, C-I, and C-II was H Sekihara has had Wolff-Parkinson-White syndrome 68%, 19%, 50%, and 40%, respectively. age years, a decrease in The present study showed pancreatic exo- Correspondence to: since the of 5 slight Dr Onishi. hearing threshold from the age of 20, and crine dysfunction in families with the A3243G developed impaired glucose tolerance at the mutation. Although DM is commonly associ- Received 24 April 1997 age of 24. The proband's mother, aged 83 ated with the A3243G mutation, exocrine pan- Revised version accepted for publication 5 September years, has had DM since the age of 73 and sen- creatic dysfunction is not a recognised feature. 1997 sory hearing disturbance from the age of 80. However, it is worth noting that a significant 256 Onishi, Hanihara, Sugiyama, et al degree of exocrine pancreatic dysfunction is a I'I. feature of Pearson syndrome (McKusick No 26056), a disease associated with deletions of A mtDNA.56 J Med Genet: first published as 10.1136/jmg.35.3.255 on 1 March 1998. Downloaded from The electron microscopic appearance at necropsy of the pancreas of patient A-II is characteristic. Accumulation of vacuolar mito- chondria seen in degenerative acinar cells is analogous to that seen in skeletal and cardiac muscle cells'2 13 as well as smooth muscle and ri i_endothelial cells of the cerebral vessels'4 of patients with mitochondrial encephalomyopa- thy. These findings led us to investigate pancreatic exocrine function. .L= B~The percentage recovery of PABA was variable between patients regardless of age. The clinical phenotype of mitochondrial dis- ease depends on the level of heteroplasmy in -2 each organ, organ threshold, and age.'5 16 In our patients, the percentage of mutant mtDNA in the exocrine pancreas may be different. -_ 1SL Pancreatic exocrine dysfunction was recog- nised only by the bentiromide test, which is non-invasive and has a significant correlation with the results of the pancreozymin secretin test.9 However, the bentiromide test showed relatively little impairment. These data, to- IC ^7 6 A2 VI; !-tr !: gether with the minimal changes in pancreatic cell morphology, indicate that the pancreatic exocrine dysfunction in these patients is subtle. One patient (A-II) showed chronic diarrhoea in the later stages of the disease. This might have V71-7 777-71 resulted from steatorrhoea, although this was M Ei-Pp%;,-'---'. -, i iI t [i Z'i !i, i-. .< :iiLll ;.-. r.-zjIt, not documented clinically. In conclusion, we observed variable clinical symptoms in the patients and our results indi- -cate that exocrine pancreatic dysfunction may 60MELF h , ! , be associated with the A3243G mutation. IL.4z http://jmg.bmj.com/ "x!IaI\ iit /aIIIihI - This work was supported by a research grant from the UNIVERS foundation to HO and from the Japanese Ministry of Education, Science and Culture (C-0967048) to SS. We are grateful to Dr Ken Inoue, Dr Kyoko Suzuki, Dr Tomohiro Miyakawa (Department of Psychiatry, Yokohama City Univer- Figure 1 Identification and quantitation of the A3243G mutation ofthe mitochondrial sity), Dr Hitoshi Osaka, and Professor Palmer Taylor (Depart- tRNAI,e(UUR) gene in white blood cells (B) ofall the patients and ofthe quadriceps muscle ment of Pharmacology, University of California, San Diego) for (Q) andpancreas (P) ofnecropsy samplesfrom patient A-II. The percentage of mutant their kind suggestions, without whose cooperation this work mtDNA and the percentage recovery ofPABA are shown. M: size marker. would not have been possible. on September 25, 2021 by guest. Protected copyright. 1 DiMauro S, Moraes CT. Mitochondrial encephalomyopa- thies. Arch Neurol 1993;50:1 198-208. 2 Hammans SR, Sweeney MG, Hanna MG, et al. The mitochondrial DNA transfer RNA'Lu('") A-G(.3243I muta- tion. Brain 1995;118:21-34. 3 van den Ouweland JMW, Lemkes HHPJ, Ruitenbeek W, et al. Mutation in mitochondrial tRNA!-lUUR) gene in a large pedigree with maternally transmitted type II diabetes and deafness. Nat Genet 1992;1:368-71. 4 Maassen JA, Kadowaki T. Maternally inherited diabetes and deafness: a new diabetes subtype. Diabetologia 1996;39: 375-82. 5 Pearson HA, Lobel JS, Kocoshis S, et al. A new syndrome of ... sideroblastic anemia with vacuolation of marrow precur- sors and exocrine pancreatic dysfunction. Jf Pediatr .g. !.. ... ., 1979;95:976-84. 6 Rotig A, Colonna M, Bonnefont JP, et al. Mitochondrial w s~~~~~~~~~~~~~~~~~~~... .w,,.., DNA deletion in Pearson's marrow/pancreas syndrome. Lancet 1989;i:902-3. 7 Onishi H, Inoue K, Osaka H, et al. Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes <Xn4DI>i'*'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~........0M (MELAS) and diabetes mellitus: molecular genetic analysis and family study. _J Neurol Sci 1993 114:205-8. 8 Onishi H, Kawanishi C, Iwasawa T, et al. Depressive disor- der due to mitochondrial tRNAIu(UUR) mutation.