Osteogenesis imperfecta

Japanese: 骨形成不全症 - こつけいせいふぜんしょう（英語表記）Osteogenesis imperfecta

What is the disease?

There are several classifications based on severity and complications, but a common feature is a tendency to fracture bones, which can lead to deformities of the bones in the legs and arms.

What is the cause?

Osteogenesis imperfecta is a hereditary disorder, and if one of your parents has the disorder, there is a 50% chance of inheriting it from that parent. Autosomal dominant ( Senior citizen of the United States ) Although it is primarily genetic, it can take other forms of inheritance. It can also develop as a result of a mutation, and is not necessarily inherited from parents (it can also be born to healthy parents).

Most cases are caused by mutations in the gene for type 1 collagen, which is important in bone formation.

How symptoms manifest

In addition to symptoms such as a tendency to break bones and deformation of the bones in the legs and arms, Scoliosis ( Sokuwan ) or rib cage ( Religion ) It is often accompanied by bone abnormalities such as deformity and short stature. Blue Sclera ( Good at school ) , Teeth ( Shiga ) It may also be accompanied by hypoplasia, skin abnormalities, and hearing loss.

Generally, bone Vulnerable ( Luxury ) Since the condition improves with bone maturation, fractures become less likely from childhood to adulthood. However, in women, the condition tends to worsen after menopause. There is no intellectual disability or mental development disorder, but there is a need for movement disorders due to fractures and movement restrictions to prevent fractures.

Classification

① Type 1 is associated with blue sclerosis and adult hearing loss. Fractures vary but are often mild.

②Type 2 Type 2 is severe and often results in stillbirth or early death after birth.

③Type 3 is a severe type, but the symptoms are slightly milder than type 2.

Type 4: Moderate severity, characterized by the absence of blue sclerae.

In recent years, the classification has been further subdivided into five to seven types.

Diagnosis and testing

If the above symptoms are present, osteogenesis imperfecta is suspected, but a definitive diagnosis is made by X-ray examination to confirm the poor ossification of the whole body, fractures and regeneration, and the skull. Thinning ( Hihakuka ) The diagnosis is confirmed if the following are observed. Blood tests using bone metabolism markers show signs of increased bone metabolism.

Treatment methods

Bisphosphonates are administered as drug treatment, and for fractures and deformities of long bones, Intramedullary nail ( Zunai ) Surgery is an option, but there is no cure.

Hideaki Sawai

Osteogenesis imperfecta
Dysosteogenesis
(Childhood illnesses)

What is the disease?

A systemic connective tissue disease caused by an abnormality in type I collagen, affecting bones. Vulnerability ( Adult ) This causes frequent fractures and bone deformities. It is a hereditary disease, occurring in approximately 1 in 20,000 people.

How symptoms manifest

Symptoms vary, ranging from severe cases that cause death shortly after birth to cases that are almost asymptomatic and are discovered by chance. Symptoms include: Easy ( stomach ) Weakness of long bones, such as fracturing (easily breaking bones) and progressive bone deformity spine ( Spinal cord ) In addition to the transformation of Blue Sclera ( Good at school ) , Dentin ( Elephant room ) These include hypoplasia, growth retardation, hearing loss, and hyperextensibility of the joints and skin.

Depending on the severity, blue sclerae, and the presence or absence of dentinogenesis imperfecta, it is classified into types I to IV. Recently, it has been discovered that there are cases that do not fall into this classification and are not caused by collagen abnormalities, and these have been newly classified into types V, VI, and VII.

Testing and diagnosis

It is diagnosed by repeated fractures due to minor external forces, blue sclerae, X-ray findings, bone density measurements, etc. In mild cases, diagnosis may not be easy. On X-rays, the important finding is the appearance of numerous small islands of bone in the skull. Bone density is significantly low.

Diseases that must be distinguished include diseases that cause bone fragility, such as rickets, as well as abused child syndrome.

Treatment methods

In addition to surgical treatment for fractures and deformities of the long bones of the limbs, the recently introduced drug therapy using bisphosphonate preparations has proven remarkably effective.

Yoshitaka Yamanaka

Source: Houken “Sixth Edition Family Medicine Encyclopedia” Information about the Sixth Edition Family Medicine Encyclopedia

Japanese:

どんな病気か

　重症度と合併症により、複数の分類がありますが、骨折しやすく、これによって脚や腕の骨の変形を伴うことが共通の特徴です。

原因は何か

　骨形成不全症は遺伝性疾患で、両親のいずれかがこの疾患であって、その親から50％の確率で遺伝する常染色体優性(じょうせんしょくたいゆうせい)遺伝が基本ですが、その他の遺伝形式をとる場合もあります。また突然変異で発症することもあり、必ず親から遺伝するわけではありません（健常な両親から生まれることもあります）。

　原因のほとんどは1型コラーゲンという骨の形成に重要な遺伝子の変異によって生じます。

症状の現れ方

　骨折しやすい、脚や腕の骨の変形を併うといった症状以外にも側彎(そくわん)や胸郭(きょうかく)変形、低身長などの骨所見を伴うことも多いです。また、眼の青色強膜(せいしょくきょうまく)、歯牙(しが)形成不全、皮膚の異常、難聴などを伴うこともあります。

　一般に骨の脆弱(ぜいじゃく)性は骨成熟とともに改善しますので、小児期から成人期にかけて骨折は起こりにくくなります。しかし女性の場合には、閉経後に悪化する傾向があります。知的障害や精神発達障害はありませんが、骨折による運動障害や、骨折を予防するための運動制限の必要性はあります。

分類

①1型　眼の青色強膜と成人期の難聴を伴います。骨折はさまざまですが、軽度の場合が多いです。

②2型　2型は重症で死産になったり、出生後の早期に亡くなることが多いです。

③3型　重症型ですが、症状は2型よりやや軽度です。

④4型　中等度の重症度で、青色強膜を伴わないことが特徴です。

　近年は分類が細分化されて5～7型までに分類されることもあります。

診断と検査

　前記の症状があった場合に骨形成不全症が疑われますが、診断確定はX線検査で全身の骨化不良、骨折と再生像、頭蓋骨で菲薄化(ひはくか)等がみられれば確定します。血液検査では骨代謝マーカーを用いた検査で、骨代謝の亢進所見がみられます。

治療の方法

　薬剤治療としてビスホスフォネート製剤の投与、長管骨の骨折や変形に対しては髄内釘(ずいないてい)手術などが行われますが、根治的な治療方法はありません。

澤井　英明

骨形成不全症
こつけいせいふぜんしょう
Dysosteogenesis
(子どもの病気)

どんな病気か

　Ⅰ型コラーゲンの異常により生じる全身性の結合組織の病気で、骨の脆弱性(ぜいじゃくせい)から頻回の骨折、骨変形を生じます。遺伝性の病気で、発生頻度は約2万人に1人です。

症状の現れ方

　症状はさまざまで、生後すぐ死亡する重症型から、偶然発見されるほとんど無症状のものまであります。症状は、易(い)骨折性（骨折しやすい）・進行性の骨変形などの長管骨の脆弱性と脊椎(せきつい)の変形に加え、青色強膜(せいしょくきょうまく)、象牙質(ぞうげしつ)形成不全、成長障害、難聴、関節・皮膚の過伸展などです。