What is Atelosteogenesis ?
Atelosteogenesis is a disease which affects small children and infants in common. This disease usually affects the development of bones in the body of children. Atelosteogenesis is further bifurcated into three types: Atelosteogenesis type I, Atelosteogenesis type II and Atelosteogenesis type III. All of these diseases affect the bones of the children and can also have an effect throughout the body.
Types of Atelosteogenesis
- Atelosteogenesis Type I. This disorder affects the development of bones throughout the body in infants. Atelosteogenesis type I is characterized by inward and upward-turning feet, dislocation of hips, knees, and elbow. There is the absence or underdevelopment of bones of the spinal cord, rib cage, and limbs1. This results in bone abnormalities and shortened length of the bones of hands and legs.
- Atelosteogenesis Type II. This is a severe disorder affecting the cartilage and the bone development in infants2. Infants who face this condition have a prominent rounded abdomen, narrow chest and short bones of hands and legs. This disorder can also include cleft lip and unusually positioned thumbs.
- Atelosteogenesis Type III. This type is similar to type I where there is shortened growth of the bones of hands and legs and abnormalities are found in the bones of knees, hips, and elbows3,4. In this disease, the hands and feet are wide and broad and maybe permanently bent. This also includes a broad forehead, widened eyes, and underdeveloped nose.
Causes of Atelosteogenesis
Mutations of the FLNB gene are responsible for causing atelosteogenesis Type I and III1,3,4. This gene gives instructions for the formation of filamin B which helps to develop a network of protein filaments that allows cells to change shape and structure and move. Filamin B is very important for the development of the skeleton before birth. Mutations of the FLNB gene restrict the working of filamin B. Atelosteogenesis Type II is a skeletal disorder that is caused due to the mutations of the SLC26A2 gene2. These genes give instructions to the proteins which are essential for the development of cartilage. Mutations in these genes hinder the performance of the proteins leading to underdevelopment of bones which later results in skeletal problems.
Epidemiology of Atelosteogenesis
Atelosteogenesis is considered to be a very rare disorder wherein only a few people have been reported with this disease. Only a dozen people till date are known to be affected by Atelosteogenesis Type I1. While, the incidence of atelosteogenesis type II is still unknown2. Atelosteogenesis Type III is known to have affected nearly two dozen people by now3. The infants are mostly still born. Even if they are live born, the infants do not survive for long considering the gross effect the disorder has on them.
Inheritance of Atelosteogenesis
Atelosteogenesis of all types is considered to be an autosomal dominant pattern inheritance from parents which means that only one pair of the affected gene is enough to cause the disease in the child.
Symptoms of Atelosteogenesis
- The symptoms of Atelosteogenesis Type I includes 11 pairs of ribs, hypoplasia of the ulna, shortened fingers and toes, elbow dislocation1. It might also cause cardiorespiratory failure due to pulmonary hypoplasia.
- The symptoms of Atelosteogenesis type II include hitchhiker thumbs, small chest, cleft palate, protuberant abdomen2.
- The symptoms of Atelosteogenesis type III include abnormal cervical curvature; knee, hip and elbow dislocation, vertebral hypoplasia, clenching hands3,4.
Diagnosis of Atelosteogenesis
This disease can be diagnosed easily as their symptoms are visible at the birth of the child. If even a few symptoms are witnessed, the disease can be confirmed by a doctor.
Treatment of Atelosteogenesis
The treatment of Atelosteogenesis is not possible. One cannot completely cure the affected person but can get treatments and surgeries done in order to avoid certain side effects and symptoms of the disease. Symptomatic management can be done with regards to the associated problems caused by Atelosteogenesis.
Atelosteogenesis is a rare genetic disorder which is inherited by the child through his/ her parents in an autosomal dominant recessive manner. It is further classified into three types each of one affecting the bones throughout the body. The symptoms of this disease vary widely in different types where Type 1 includes shortened fingers and toes, elbow dislocation, 11 pairs of ribs, and so on1. Type 2 includes a rounded abdomen, thin chest, shortened bones of hands and legs and cleft lip2. Type 3 includes abnormalities in the bones of knees, hips and elbows, widened eyes and broad forehead3,4. Till date, there is no treatment or cure for Atelosteogenesis and symptomatic management is the only way to deal with it.
- Stern, H., Graham, J., Lachman, R., Horton, W., Bernini, P., Spiegel, P., Bodurtha, J., Ives, E., Bocian, M. and Rimoin, D. (1990). Atelosteogenesis type III: A distinct skeletal dysplasia with features overlapping atelosteogenesis and oto-palato-digital syndrome type II. American Journal of Medical Genetics, 36(2), pp.183-195.