Glass bone disease – causes, symptoms and treatment

Glass bone – Osteogenesis imperfecta

The Osteogenesis imperfecta “means imperfect bone formation”, and is colloquially known as glass bone disease. This rare hereditary disease is based on particular genetic defects that affect collagen budget. In order for the Affected to disorders in the connective tissue and in bone metabolism. The result is a deformable and slightly more fragile cooking is the leading Symptom, which is behind the pictorial concept of glass bones. The treatment is based exclusively on symptomatic therapies to prevent bone fractures and to provide the best possible.

Table of contents

A brief Overview

In the following Overview the most important facts are listed about the topic of the rare genetic disease Osteogenesis imperfecta. Detailed information about the complex clinical picture are to be found in the article below.

  • Definition: Osteogenesis imperfecta (glass bones, glass bones disease) is a hereditary Collagen malformation, which is primarily a connective tissue disorder. In particular, the disease to an imperfect bone formation, which manifests itself on the leading Symptoms of increased bone fractures and bone deformations.
  • Symptoms: in addition to the abnormally high susceptibility to spontaneous fractures and bone deformation causes the disease, a variety of other complex Symptoms. Typical symptoms include, among other things, muscle weakness, and blue Sclera. The severity of the disease ranges from very mild forms to lethal forms.
  • Causes: triggers are different gene mutations for disorders in the formation of collagen (collagen type 1) are responsible. Collagen is the main constituent of connective tissue and is an important building block for the bones and other structures and tissues. Therefore, it is not only interference in the entire musculoskeletal system but also in many other areas of the body.
  • Diagnosis:in addition to a thorough history and clinical examination, especially x-ray examinations in the diagnosis. A hedge of the diagnosis can be a genetic proof. Before birth are more severe forms of the disease, often by means of prenatal ultrasound visible.
  • Treatment: The medical treatment of symptoms is based mostly on relatively new drugs (Biophosphonate), orthopedic measures and ongoing physiotherapy. The treatment options are still in development. In addition, General measures to promote health and osteopathic treatment can be consulted.
  • Current research: Current research into the causes of disease (molecular genetics) and treatment options the understanding of this rare genetic disease extend and Affected in the best possible care.

Definition

The medical term Osteogenesis imperfecta (General abbreviation: OI) is derived from the Greek and refers to an imperfect bone formation. In General, use of language, but used mostly the concepts of glass, bone, or glass bone disease, related to the main symptom of increased bone fractures. First and foremost, it is the disease but a rare hereditary connective tissue disorder, which occurs due to various genetic defects and leads to a Collagen malformation (type I collagen). Osteogenesis imperfecta occurs in about one of 20,000 births.

Classification and clinical features

A variety of different genetic defects, and thereby caused disturbances in the collagen composition lead to this disease. Due to the different symptoms in the Affected, and the disease shows a great variability in the severity and course of the disease.

In 1979 a Four-type classification is introduced, the different forms of disease and their clinical features divided was for the first time. The description of the types I to IV, back to the Australian physician David Sillence. In the case of these four forms of mutations of the collagen type 1 coding occur in the genes (COL1A1 or COL1A2), which are in Europe more than 80 percent of the cause of the disease.

Continuously new genetic and clinical findings have led to the expansion of this division. Currently, eleven types are described in which additional genes, and mutation of the forms are taken into account. However, only the types I to VI to find a largely uniform use. To this day, not all characteristics can be mapped, because the large number of causal genes more difficult for an unambiguous classification. The extended classification is therefore still in discussion and there is a need for education persists, unclassified forms of the disease.

The common type I with a mild form is also known as Osteogenesis imperfecta tarda, or type Lobstein known and the most severe, lethal Form of type II is known as Osteogenesis imperfecta congenita or type Vrolik.

Symptoms

In spite of the high variability in the presenting symptoms and, in nearly all cases of the disease the abnormally high innate susceptibility of the bone to fractures (Osteopsathyrose) in the foreground. The bone fractures occur as a result of a reduced bone mass and a lack of stability and elasticity without adequate trauma (spontaneous fractures).

In addition, it also comes to (strong) skeletal deformations, in particular of the long bones in the extremities and the spine (scoliosis, kyphosis), and short stature.

In addition to these main symptoms may occur depending on, among other things, the following additional symptoms:

  • Muscle weakness, decreased muscle tone (hypotonia),
  • include hyperextensible joints and ligaments,
  • stand-alone bone Islands (wiring of bone) on the skull,
  • blue Sclera (leather skin of the eye),
  • Hard-of-hearing,
  • Short-sightedness,
  • Heart problems,
  • Lung disorders (deformities of the chest),
  • Discoloration and brittleness of teeth (Dentinogenesis imperfecta),
  • Haematoma inclination,
  • soft, translucent skin,
  • triangular face shape with wide forehead and protruding ears.

Course of the disease

The many possible complaints and levels of severity require individually very different disease courses. In the case of medium and severe disease months, fractures and deformities occur gradients already during the first life to the extremities and the spine. Particularly critical is the growth phase up to adolescence, during which already occur under very slight force, again and again fractures.

But even before the child is born already fractures, deformities, and other abnormalities of the bones can occur. The most severe Form (type II) is the disease either prenatally lethal or it is to be expected in the first months of life with a fatal course. More severe forms can Be due to the frequency of occurring fractures and possible bone bending, the Affected on and Go stop.

A mild Form of the disease (type I), in contrast, is Concerned mostly with only a few fractures in her Childhood and youth without any further restrictions. Many forms of the disease have in common that the fracture rate goes back to the end of puberty.

In principle, forms and corresponding therapy applications no reduction in life expectancy is the life.

Causes

The rare genetic disease is inherited primarily in an autosomal dominant. An inheritance takes place, therefore, regardless of the gender, and the disease can manifest itself if the gene defect is on only one of the 22 autosomes pairs (body chromosomes). If none of the two parents has to transfer disease, in addition, a spontaneous mutation as the trigger in question.

The most common genetic mutations associated with this disease, lead to quantitative or qualitative disorders in the formation of collagen. In most cases, the type I collagen is affected, which will set the General collagen term, which is often the same. Collagens are the most common fiber-forming proteins (structural proteins, fiber proteins) with binding and supportive functions in different Parts of the human body. Type I collagen is the main constituent of the connective tissue. Likewise, it is an important building block for bones, cartilage, Tendons, ligaments, teeth, and skin, as well as the conjunctiva (conjunctiva). The disease affects not only the skeletal system but to the entire musculoskeletal system, and all other structures containing collagen to a certain proportion of type 1.

Despite the clear cause of the gene mutation, is this even with the latest methods in each case genetically detectable.

Diagnosis

The first evidence of the diagnosis provides the patient survey (medical history), in addition to the typical symptoms of a family of Osteogenesis Occur will be clarified imperfecta. In addition, physical examinations, x-rays and laboratory tests, other possible disorders ruled out that in the age of the child occur (for example, rickets and Hypochondroplasia). Of particular importance to the exclusion of the causal trauma to this bone fractures. This can also be used in suspected cases of child abuse relevant to miss.

In the x-ray image, an increased transparency of the bone. The structures appear glass-like because of the lack of shadow imaging of bone substance is present. The outer layer is mostly diluted as a line. Often a callus formation is visible. This is scar tissue, which widens the bone at the fracture and deformed.

In addition, a bone density measurement can provide information about the disease, because Affected the bone density is significantly reduced. A reliable description of the bone structure and the muscle-bone interaction is not a computer tomography, but in the case of each Affected applicable (minimum body size).

Also complaints to other structures and organs arise in addition to the symptoms in the skeleton, we will investigate this clinically.

A protection and extension of the diagnosis provides genetic testing for the causative gene mutations will be sought. While it is not possible in every case of the disease and the underlying gene defect to prove, but a possible identification, in addition to the diagnostic determination of the further classification and clarification of one’s own inheritance risk. A Post-setting was provided, but this does not at the same time, a reliable statement on the individual expression, or viability can be made. Prior to the birth of a cytogenetic examination is performed with the help of a nut cake puncture (chorionic villus sampling).

In General, can be difficult to verify the forms of glass weigh bone disease in the mother’s womb during a prenatal ultrasound. Typical findings including shortened and deformed limb bones, rib fractures and, occasionally, Callus formations.

Treatment

So far, there are no opportunities for tackling the root Causes or cure of this hereditary disease. The symptomatic treatment support to the three school medically recognised pillars of pharmacological treatment, orthopedic treatment and physiotherapy treatment.

Drug Treatment

In the last few years have proven to be especially in the case of medium and severe cases, intravenously administered bisphosphonates as a successful treatment option. The drugs (for example, Neridronat and Pamidronate) cause an increase in bone mass and increase bone strength. This makes it less prone to bone fractures and improved mobility. The different bisphosphonates are not approved for the treatment of Osteogenesis imperfecta, which is why an application must be individually clarified. Only with the explicit consent of the data a so-called “individual therapeutic trial” with any of these medicines can be done. Close control studies on the effectiveness and potential side effects are essential.

Contrary to some of the treatment concepts of other bone disorders, an intake of Vitamin D and calcium is addition to the General recommendations do not make sense.

Orthopedic Treatment

The most common symptoms of bone fractures and bone deformations generally require intensive orthopedic treatment. The aim of this form of therapy is to get especially the functionality and the resilience of the skeletal system or restore it. Conservative measures in case of broken limb bones include the case of very small children, special techniques of winding and storage. Furthermore, it comes to the use of orthoses (for example splints) and plaster.

In more complicated cases, surgical procedures are necessary to prevent fractures and deformities, or to correct but to heal. In the case of operations in childhood and adolescence a consideration of the growth phase is of particular importance. This requires the use of a telescopic nail system (Bailey, or as well as personal-Duval nail). Often after several targeted bone through separations (osteotomies), two mesh slip-on nail to be inserted, parts in the Interior of the bone. The bone parts to be connected thereby and during the growth from sliding apart these nails, together with the bone. Thus, the bone can be stabilized over a long period of time.

In the case of very small children, it may be that the bone to provide sufficient space for a telescopic nail. This is the case, other tools are used, which must then be removed at a later date, or replaced.

Physiotherapy Treatment

The risk of misalignment, improper posture, and skeletal changes, an individually tailored physical therapy is of great importance to prevent. But also in the Rehabilitation after bone fractures in a targeted physiotherapy is a Central element of the therapy measures. The primary objective is to improve mobility or to increase and strengthen the muscles. Each individual should obtain a regular and continuous physiotherapy treatment and other treatment measures, this support.

Other areas of the body or organs are affected, such as the lungs or the heart, can be additional forms of therapy is necessary.

Naturopathic Treatment

The school medical procedures for the treatment of Osteogenesis imperfecta can be supported by General, health-promoting measures. So as much movement as possible, sports (Swimming), and avoiding cigarettes and alcohol have a positive effect.

In addition to the physiotherapeutic treatment of the measures in the field of osteopathy can help to relieve the symptoms. A visit to the naturopath can also be helpful.

Current State Of Research

Although the disease is already known for a long time, require the complex genetic basis and widely varying disease manifestations of intense research, particularly in the area of the causes of disease and the individual treatment options.

In 2017 published consensus paper in the “monthly journal of Pediatrics” studies and research approaches in the field of application of Biophosphonaten and other medicines, such as, for example, the effects of parathyroid hormone as a bone formation-stimulating drug in adults. Also for the field of Gene and cell therapy as a treatment option in international studies are carried out.

Recently, the modification of collagen has been decrypted, which is very likely in the case of the glass-bone disease, is to account for the reduced resistance of the bone responsible.

Since it is a rare disease, there are no defined guidelines for the care of the person Concerned. In the training journal “Pediatrics hautnah” have summarized the German doctors in charge for a long time, children and adolescents with Osteogenesis imperfecta, the current state of the disease picture. (tf, cs; updated on 17.12.2018)

Further Information:
German society for Osteogenesis imperfecta (glass bones) betroffene e. V.
Osteogenesis imperfecta – Information for Affected persons and relatives