Osteoonychodysplasia is a mutational malformation syndrome with predominant involvement of the limbs. In addition to skeletal abnormalities, kidney and eye involvement is common. The primary goal of symptomatic treatment is to delay terminal renal failure.
What is Osteoonychodysplasia?
Malformation syndromes are characterized by the dysplasia of various structures of the anatomy. In medicine, dysplasia is the malformation of tissues or organs. Dysplastic phenomena are present, for example, with underdevelopment or overdevelopment. Osteoonychodysplasia is a congenital malformation syndrome with predominant involvement of the extremities. It is associated with various malformations and functional disorders of different organs. See theinternetfaqs for Short Stature Basics.
A well-known disease from this group is, for example, nail-patella syndrome, which is associated with deformities of the fingernails and bones. A subgroup of osteoonchyodysplasias, nail-patella syndrome occurs in approximately 1 case in 50,000 newborns worldwide. Girls are affected just as often as boys. The age of onset is considered to be infancy.
Osteoonychodysplasia is also known as Turner-Kieser syndrome and is associated with heredity. The hereditary disease was first documented in the 1920s and 1930s. The American Turner, the German Kieser and the Austrians Trauner and Rieger are considered the first to describe it.
Causes
Osteoonychodysplasia is a hereditary disease. The symptom complex is inherited in an autosomal dominant mode of inheritance. The parents of an ill parent therefore have a 50 percent risk of contracting the malformation syndrome. Familial clustering was therefore observed in most cases. However, sporadic cases have also been observed.
The primary cause for both variants is a genetic mutation, which corresponds to a new mutation if it occurs sporadically. The mutation appears to affect the LMX1B gene on the longer arm of chromosome 9. The gene locus is 9q34. The previous studies on osteoonychodysplasia suggest more than 80 different mutations of the same gene as the cause of the disease. The LMX1B gene is a limb transcription factor derived from the group of LIM homeodomain proteins.
These proteins are involved in the development of the extremities, kidneys and eyes. Depending on the involvement of the kidneys, nail-patella syndrome is causally associated with different alleles. A mutation of the LMX1B gene leads to a loss of function of the transcription factor, impairing development. The disease is associated with the ABO system of blood groups.
Symptoms, Ailments & Signs
Osteoonychodysplasia patients suffer from deformed skeletal structures. The malformations of her bones and joints are particularly impressive in the x-ray as an underdeveloped patella. There is often a bony exostosis on the right iliac crest or the posterior horn of the pelvis. Involvement of the patella affects more than 90 percent of patients.
A complete failure of the structure occurs in almost a quarter of all cases. The underdeveloped and partially dislocated patella makes the patient’s knees partially unstable, so that motor development is delayed and falls are more likely. The patient’s elbows can only pronate or supinate to a limited extent. The radial head is often subluxated. In most cases, the disease is associated with arthrodysplasia of the elbow.
The joints of the limbs are usually capable of hyperextension. Other case reports have documented bony abnormalities such as scoliosis, formation of cervical ribs, and underdevelopment of the nails in the syndrome. In individual cases, these symptoms can be associated with kidney problems that can trigger proteinuria or nephritis.
Other accompanying symptoms can be hypothyroidism, irritable bowel syndrome, attention deficit disorder or thin tooth enamel. Eye symptoms and sensorineural hearing loss often complete the symptomatic picture.
Diagnosis & course of disease
The first suspected diagnosis of osteoonychodysplasia is presented to the doctor via X-ray imaging, which shows the characteristic changes in the skeleton. In addition, characteristic changes in the glomerular basement membrane can often be detected by electron optics.
A molecular genetic analysis is not necessary in most cases, since the clinically typical picture alone confirms the first suspected diagnosis. The prognosis of the patient depends on the severity of the individual case. With severe organ involvement, the syndrome can be fatal.
Complications
Since osteoonychodysplasia is a symptom complex of various hereditary diseases, the risk of complications for the affected patients varies. For example, life expectancy is not reduced in the so-called nail-patella syndrome, which is characterized by deformation of the fingernails and bones. In the other forms of osteoonychodysplasia, however, internal organs are often involved.
More than 50 percent of patients suffer from renal insufficiency. The course of the kidney disease in particular determines the prognosis of the disease. Renal insufficiency often progresses and leads to the patient requiring dialysis. In these cases, curative therapy is only possible with a kidney transplant. This is especially true if there is a risk of total failure of both kidneys.
Other complications observed with osteoonychodysplasia include scoliosis, clubfeet, exotosis (bunions) or malformed elbow joints. In these cases, orthopedic treatments are necessary. Sometimes cardiac arrhythmias or glaucoma occur as complications. The prognosis of cardiac arrhythmia varies from person to person.
To avoid long-term heart disease, treatment by a cardiologist is important. Glaucoma can lead to blindness later if the intraocular pressure is not reduced. The deformation of the bones and fingernails themselves can have a psychological impact on the patient if they feel socially excluded because of their appearance.
When should you go to the doctor?
If optical irregularities or malformations of the skeletal system are noticed immediately after birth, a health check should be carried out immediately. If the birth takes place in the midst of an obstetric team, the parents normally do not have to take any further measures. Midwives and doctors independently record the state of health of the baby and document any abnormalities. All deviations are identified in imaging procedures and other examinations and a diagnosis is made.
If there are health deviations, delays or underdevelopment in the further development and growth process, the observations should be discussed with a doctor. A doctor is required in the event of hearing loss, the possibility of hyperextension of the joints or an optical defect in the nail shape.
An abnormal sequence of movements often takes place in everyday life, which can be interpreted as an indication of a disease. Thin tooth enamel, attention disorders or low physical and mental resilience should be presented to a doctor. Irregularities in urination or kidney function must also be examined and treated by a doctor.
If symptoms of deficiency appear despite an adequate and balanced diet, this can be a warning signal from the organism. A check-up visit to a doctor is necessary so that the cause of the symptoms can be found. Disorders of elbow activity and an optical change in the joint are noticeable in osteoonychodysplasia.
Treatment & Therapy
A causal treatment is currently not available for patients with osteoonychodysplasia. The disease cannot be cured as long as gene therapy approaches do not reach the clinical phase. Gene therapy may make the complex of symptoms a curable disease in the future, but at the moment patients are only treated symptomatically.
If the kidneys are involved, the treatment of proteinuria is the focus of therapy. This symptom can lead to kidney failure. Therefore, a reduction in proteinuria must be aimed for in the therapy of nephropathy. However, most patients develop kidney failure around the age of 30. Kidney transplantation is the treatment of choice at this stage.
The skeletal dysplasia of osteoonychodysplasia can also be corrected with reconstructive surgery. This applies, for example, to non-application of the patella. Physiotherapy may be needed to stabilize the skeleton. The targeted build-up of muscles provides support for the mostly hypoplastic bones and joints.
Physiotherapy also promotes normal motor development. Symptoms such as nail hypoplasia are more of a cosmetic problem and do not necessarily need to be corrected immediately. If treatment of the nail hypoplasia is nevertheless desired, a nail bed transplant is usually carried out.
Outlook & Forecast
As a rule, it is recommended to consult a doctor as soon as the first symptoms of osteoonychodysplasia appear, as this can promote the further course of the disease. Since this genetic disease cannot be cured, those affected are dependent on purely symptomatic treatment, which aims to reduce proteinuria and thus delay terminal kidney failure.
It is particularly important to strictly follow the doctor’s instructions. This usually includes taking diuretics and corticosteroids, avoiding alcohol consumption, regular monitoring of kidney function, a balanced diet and a healthy lifestyle. A visit to physiotherapy with accompanying exercises to do at home is also advisable, since the skeleton and motor skills can benefit from stronger muscles and thus the course of the disease can be positively influenced.
If all of these medical recommendations are consistently followed, the time of kidney failure can be delayed to the age of 30 in one third of the patients. Since patients very often feel excluded because of their clearly visible deformities, psychotherapeutic treatment or visiting self-help groups can be of great help to improve the quality of life.
However, the life expectancy of the patient is often significantly reduced due to kidney failure. This can only be counteracted by a kidney transplant as a final treatment option, which is usually carried out shortly before the age of 30. This can completely prevent the disease from flaring up again in the transplant and thus offer a very good prospect of future living conditions. If the patient wishes to have children, genetic testing and counseling would be recommended, which can rule out the hereditary occurrence of the disease.
Prevention
Osteoonychodysplasia can at best be prevented in the form of genetic counseling during the family planning phase.
Aftercare
In most cases, the person affected with osteoonychodysplasia has no special or direct follow-up measures available, so that the person affected with this disease should definitely consult a doctor very early on. The sooner a doctor is consulted, the better the further course of the disease. A doctor should therefore be contacted as soon as the first signs and symptoms appear.
Since this is a genetic disease, the person concerned should definitely have a genetic test and counseling carried out if they wish to have children in order to prevent the disease from recurring. Most of those affected are dependent on the permanent examination of the kidney.
Drinking alcohol should also be avoided as much as possible. In general, a healthy lifestyle with a balanced diet has a positive effect on the further course of the disease. Physiotherapy measures are also very important, and the affected person can also carry out many of the exercises themselves at home. It is not uncommon for osteoonychodysplasia to reduce the life expectancy of those affected, as it often leads to kidney failure.
You can do that yourself
Osteoonychodysplasia cannot be cured, but its negative effects can be mitigated using certain methods. With symptomatic therapy, it is important to strictly follow the doctor’s recommendations. Treatment includes regular use of corticosteroids and diuretics. Depending on the degree of severity of the genetic defect, dialysis therapy is often already available in infancy.
A lot of patience is required, especially in severe cases with malformations of the spine or extremities. With help in everyday life, the problems with locomotion and various activities can be reduced. In the case of a foot deformity, special insoles or shoes are used to make it easier for those affected. If the pelvic bone is also damaged, further support measures may be necessary.
The psychological consequences for the patients play a very important role. They often feel excluded, especially when there are clearly visible deformities. Visiting self-help groups is recommended for a better quality of life. In the family, too, it makes sense to talk about the problem and look for practical solutions.
A special diet can help with kidney failure. In addition, the skeleton is strengthened by stronger muscles. With regular physiotherapy, the body gets more strength and motor skills develop normally.