What is the disease? Wilson's disease is Excessive copper deposition in the cells of organs throughout the body, particularly in the liver, brain, cornea, and kidneys, results in various clinical symptoms based on the resulting cell and organ damage. What is the cause?As mentioned above, Wilson's disease is based on an autosomal recessive inheritance pattern. The carrier rate in Japan is estimated at 1 in 100-150 people, which is higher than the 1 in 200 people in Europe and the United States, so it is by no means a rare disease. Furthermore, the incidence of homozygous carriers is 1 in 40,000-90,000 people. The number and distribution of patients varies by region, and the carrier frequency is influenced by the rate of incestuous marriage. Therefore, when interviewing the mother and family, it is especially important to know whether or not the parents have engaged in incestuous marriage. Recently, a mutation in the ATP7B gene on chromosome 13 has been identified as the causative gene for Wilson disease. ATP7B is an ATP-dependent metal transporter that is specifically expressed in the liver, and this mutation impairs copper uptake into ceruloplasmin, causing impaired excretion of copper into the bile. How symptoms manifest It shows various clinical symptoms, especially cirrhosis of the liver, The primary organ in Wilson's disease is the liver, which is damaged by The most common age for onset is between 5 and 20 years old, but it can also occur between 30 and 40 years old. Because excess copper accumulation begins in the liver, liver damage usually precedes neurological symptoms. This is why liver damage is generally common in Wilson's disease that begins at a young age of 10 or younger. As people age, excess copper begins to accumulate in the basal brainstem, kidneys, and corneas, in addition to the liver. Therefore, after the age of 10, neurological and psychiatric symptoms are more likely to appear onset. Clinical disease type As shown in Table 11, the clinical types of Wilson disease are broadly classified into 1) presymptomatic type (asymptomatic period), 2) hepatic type (common in children under 10 years of age), 3) neurologic type (common after age 10 and increases with age), and 4) hepatic-neurological type (similar to the neurologic type). The hepatic types include the acute fulminant hepatitis type (abdominal Wilson type) and the hemolytic type. These are cases where symptoms of acute liver failure and hemolytic anemia similar to fulminant hepatitis occur. Staging The stage (natural history) of Wilson disease is usually classified into stages I to III. Stage I is asymptomatic and progresses to diffuse copper deposition in the hepatic cytoplasm. In stage II, the copper-binding capacity of the hepatic cytoplasm becomes saturated, and the excess copper is redistributed within the liver and released from the liver. This redistribution is gradual in two-thirds of patients, but occasionally it is rapid and leads to massive hepatocyte necrosis. In stage III, liver fibrosis and cirrhosis progress. Copper is deposited in other organs and tissues, such as the brain, cornea, and kidneys, causing damage to those organs. If the rate of damage and the accumulation of copper in the central nervous system are slow, the disease may remain asymptomatic. On the other hand, if liver damage progresses rapidly, liver cell necrosis and liver failure will occur, as in stage II. If the balance of copper metabolism can be corrected through the treatment described below, the progression of liver damage and central nervous system damage can be suppressed, and in many cases symptoms will become asymptomatic, but symptoms of portal hypertension and irreversible brain damage will remain for a long time. Testing and diagnosis In infants and school-age children, the disease is often characterized by liver damage, so there are few objective symptoms. For diagnosis, it is important to interview the family, especially the mother. Early detection is essential, but when unexplained liver dysfunction is observed in young children or school-age children (particularly when accompanied by neurological symptoms such as involuntary movements), it is important to first suspect this disease. Wilson's disease is diagnosed by suspecting the possibility of a copper metabolic disorder based on a medical history and clinical symptoms, and then confirming the presence of a copper metabolic disorder based on evidence of decreased total copper and ceruloplasmin concentrations in serum, increased copper excretion in urine, and Kayser-Fleischer rings in the eyes. Furthermore, tissue diagnosis by liver biopsy ( Secondary hypoceruloplasminemia associated with other severe liver disorders, intrahepatic cholestasis, and diseases exhibiting neuropsychiatric symptoms (multiple sclerosis, cerebellar disease, Parkinson's syndrome, Treatment and prognosisThe basic principle of treatment is to promote copper excretion. Early detection and appropriate treatment can control copper metabolic disorders and significantly improve prognosis. However, if the neurological symptoms have progressed significantly, the prognosis is poor. ① Dietary therapy People are advised to limit their intake of foods high in copper (such as shellfish, liver, chocolate, and mushrooms) for the rest of their life and to follow a low-copper diet (1.5 mg or less per day). ② Drug therapy (Table 12) The first choice of treatment, including prevention of onset, is copper excretion promoters (chelating drugs: D-penicillamine, trientine hydrochloride) to remove copper accumulated in the body and reduce copper toxicity. It is important to be fully informed that this is a lifelong treatment and to understand and commit to the treatment. Symptomatic treatment for liver damage and nerve damage is also performed as necessary. D-Penicillamine (Metalcaptase) is initially administered at around 1000 mg (10 capsules) per day for Japanese people, and the dosage is increased or decreased while monitoring the effectiveness of the drug. Alternatively, the dosage can be started at 200-400 mg (taken in two divided doses) per day, and gradually increased to 800-1200 mg (200-400 mg per day for children under 5 years old). It takes several weeks to several months for the drug to take effect. Side effects of this drug include fever, cytopenia, skin rash, angular stomatitis, and systemic lupus erythematosus (SLE)-like symptoms. Be careful not to stop taking this drug once you have reached the maintenance dose. Metalcaptase has a pyridoxine antagonistic effect, so vitamin B6 should be used in combination when administering large amounts. Yasuyuki Arakawa "> Table 11. Clinical classification of Wilson's disease "> Table 12. Examples of drug prescriptions for Wilson's disease Wilson's disease |
どんな病気か ウィルソン病は、 銅が全身の臓器、とくに肝、脳、角膜、腎などの細胞内に過剰に沈着し、その結果引き起こされる細胞障害、臓器障害に基づき、さまざまな臨床像を示します。肝障害と 原因は何かウィルソン病は、前述したように常染色体劣性遺伝形式に基づいています。保因者は、日本では100~150人に1人と推定され、欧米の200人に1人という頻度よりも高く、決してまれな病気ではありません。また、ホモ保因者で発症するのは4万~9万人に1人です。患者数や分布には地域差があり、その保因者頻度は近親婚率によって左右されます。したがって、母親、家族の問診では、とくに両親の近親婚の有無が重要です。 最近、13番染色体上のATP7B遺伝子異常が、ウィルソン病の原因遺伝子として特定されました。ATP7Bは、肝に特異的に発現するATP依存性メタルトランスポーターで、この異常によってセルロプラスミンへの銅の取り込みが損なわれて、胆汁中への排泄障害が引き起こされます。 症状の現れ方 多様な臨床症状を示します。とくに肝硬変、 ウィルソン病の原発臓器である肝臓の障害は、大きく 好発年齢は、5~20歳ころまでですが、30~40歳で発症することもあります。銅の過剰蓄積は肝臓から始まるため、通常、肝障害が神経症状に先行します。一般に、10歳以下の若年発症のウィルソン病で肝障害が多いのはこのためです。その後年齢とともに、肝臓のほかに、脳幹基底核、腎、角膜への銅過剰蓄積が始まります。したがって、10歳以降では神経・精神症状での発症が多くなります。 ●臨床病型 ウィルソン病の臨床病型は、表11に示すように、①発症前型(無症状期)、②肝型(10歳以下の小児期に多い)、③神経型(10歳以降に多く、年齢とともに増加する)、④肝神経型(神経型と同様の傾向)、に大別されます。 肝型には、急性に発症する劇症肝炎型(腹部ウィルソン)と溶血型が含まれます。これらは劇症肝炎のような急性肝不全症状や溶血性貧血を伴う場合です。急激で広範な肝細胞の ●病期分類 ウィルソン病の病期(自然経過)は通常Ⅰ~Ⅲ期に分類されます。 Ⅰ期は無症状期で、びまん性の銅沈着が肝細胞質に進行します。 Ⅱ期は、肝細胞質の銅結合能が飽和状態となり、過剰な銅が肝臓内に再配分され、肝臓から放出されます。この再配分は患者さんの3分の2では緩やかに行われますが、時に急激で、肝細胞の大量壊死をもたらします。 Ⅲ期は、肝の線維化や肝硬変が進行します。銅は脳、角膜、腎など肝臓以外の臓器や組織にも沈着して、それぞれの臓器障害を起こします。その速度や中枢神経への銅の蓄積が遅いと無症状状態が続くことがあります。一方、肝障害が急速であれば、Ⅱ期のように肝細胞壊死、肝不全を起こします。 後述する治療によって、銅代謝のバランスが是正されると、肝障害や中枢神経障害の進行が抑えられて、多くは無症状となりますが、門脈圧亢進症状、不可逆性の脳障害は長く残ります。 検査と診断 幼児期、学童期の発病は肝障害型が多いため他覚的所見が少なく、診断には家族、とくに母親への問診が重要です。子どもの無気力、集中力低下、学業低下、食欲不振、動作 早期発見が最も重要ですが、幼児や学童などに原因不明の肝機能障害がみられた時には(不随意運動などの神経症状を伴っている時にはなおさら)、まず第一にこの病気を疑うことが大切です。 ウィルソン病の診断は、問診および臨床症状から銅代謝異常の可能性を疑い、血清総銅量およびセルロプラスミン濃度の低下、尿中銅排泄量の増加、眼のカイザー・フライシャー角膜輪の証明などにより、銅代謝異常のあることを診断します。 さらに、肝生検による組織診断( 他の重症肝障害に合併した二次性の低セルロプラスミン血症、肝内胆汁うっ滞症、精神神経症状を示す疾患(多発性硬化症、小脳疾患、パーキンソン症候群、 治療の方法と予後治療の基本方針は、銅の排泄促進を図ることです。早期に発見して早期に適切な治療を行えば、銅代謝異常をコントロールすることが可能であり、予後を十分に改善できます。 しかし、神経症状がかなり進行した場合には予後は不良です。死因は肝不全、 ①食事療法 生涯にわたって銅含有量の多い食物(たとえば貝類、レバー、チョコレート、キノコ類など)の摂取を制限して、低銅食(1日1.5㎎以下)にする食事指導が行われます。 ②薬物療法(表12) 体内にたまった銅の除去、銅毒性の減少を目指して、銅排泄促進薬(キレート薬:Dペニシラミン、塩酸トリエンチン)による治療が、発症予防を含めて第一選択になります。生涯にわたって必要な治療であることを十分説明してもらい、納得して治療に専念することが大切です。また、肝障害や神経障害に対する対症療法も必要に応じて行われます。 Dペニシラミン(メタルカプターゼ)は、日本人の初期量として1日1000㎎(10カプセル)前後を投与し、効果判定をしながら増減します。もしくは1日200~400㎎(2分服)から始めて、漸増して800~1200㎎を続けます(5歳以下では1日200~400㎎)。効果の発現には数週間から数カ月を要します。 この薬剤の副作用として、発熱、血球減少、皮疹、口角炎、全身性エリテマトーデス(SLE)様症状などに注意を要します。維持量に達したあとは決して中止しないように気をつけてください。リバウンド( なお、メタルカプターゼにはピリドキシン拮抗作用があるので、大量に投与する場合にはビタミンB6を併用します。 荒川 泰行 "> 表11 ウィルソン病の臨床病型分類 "> 表12 ウィルソン病での薬剤処方例 ウィルソン病
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