Hypochondrogenesis is a very rare hereditary disease that manifests itself in a variety of deformities in the human skeleton. So far only a few cases are known. It was first described in 1921. Doctors linked it to dwarfism. Thereafter, hypochondrogenesis received little attention in the medical literature and research. In 1977, the disease was redefined and differentiated from achondrogenesis, whose carriers have no viability. Since the chances of survival of newborns are very low, it is described as lethal.
What is hypochondrogenesis?
Collagen II plays a key role in building bones. The disruption of the collagen causes the bones to become deformed. See AbbreviationFinder for abbreviations related to Hypochondrogenesis.
Hypochondrogenesis is inherited in an autosomal dominant manner. The mutated genes come from either the mother or the father. Since a gene is always present twice – one from the mother and one from the father – mutated genes are usually inactivated by the other, healthy gene. In hypochondrogenesis, however, the diseased gene is dominant and switches off the healthy one (autosomal).
With this, the disease is fully expressed. It is called collagen II disease along with other diseases of a similar type. In hypochondrogenesis, an important gene fails, disrupting bone formation. Most children suffering from hypochondrogenesis die very young; many are stillborn or suffocate after birth.
However, this is a statistical fallacy because surviving children are said to be carriers of congenital spondyloepiphyseal dysplasia, a disease closely resembling hypochondrogenesis.
Causes
The cause of hypochondrogenesis is a genetic change. This disease causes the gene COL2A1 to fail. This gene is located on the 17th chromosome and controls the formation of collagen II. Genes are responsible for various construction and control tasks. In the case of a mutation, these functions can no longer be fulfilled. COL2A1 controls the assembly of collagen on the ribosomes.
The genetic information is read out, but is incorrect. The collagen molecule produced in this way is not able to carry out the normal tasks of a collagen. The cells build it into the growing bones, but the collagen molecule cannot guarantee the internal and external cohesion of the bones.
There are severe deformities in the entire skeletal structure of the human being. Children with this disease have little or no viability. Due to the disrupted skeletal structure, many children cannot breathe properly and die shortly after birth.
Symptoms, Ailments & Signs
Collagen II plays a key role in building bones. The disruption of the collagen causes the bones to become deformed. Collagen II is a protein that makes bones grow together and gives them stability. Without this protein, the bones literally melt away.
A human being cannot survive unless the body is stabilized by the skeleton. Hypochondrogenesis is manifested by very short extremities and a shortened trunk. The thorax is misshapen and the ribs very short. The spine is completely deformed and cannot do its job. In contrast, the head appears disproportionately large.
The face is flattened, from which the eyes are prominent. The abdominal area is extremely arched, which indicates a fault in the water regulation. Some stillbirths also showed other deformities of internal organs. Physicians do not agree on the relevance of these.
Diagnosis & course of disease
The diagnosis of hypochondrogenesis can be made in the womb. During pregnancy tests, the doctor takes amniotic fluid from the mother. This is examined in the laboratory. If the results are positive, the parents will be advised.
The extent to which an abortion is an option is not medically relevant, but must be clarified by the parents within the legal framework. The viability of fetuses with hypochrogenesis is very low. Most children with these symptoms are stillborn. Only a few children are born alive, but die during the first years of life.
If the pregnancy is more advanced, the doctor can make the diagnosis using an ultrasound in the womb. He examines the development of the skeletal structure of the embryo. If this shows abnormalities, he can arrange for genetic tests.
Complications
The hypochondrogenesis usually causes a very severe short stature and in most cases leads directly to the death of the patient. For this reason, no special treatment is usually possible. The bones of those affected are extremely deformed, so that the bones grow together. The stability of the bones decreases and fractures occur.
If the affected person is born directly without stabilizing the skeleton, it cannot survive and dies. Stillbirths are not uncommon. Patients’ heads are sometimes larger than normal babies, and internal organs are also deformed. In most cases, the death of the child leads to severe psychological problems and complications.
Patients suffer from depression, and partners are usually affected as well. If the diagnosis is made early, an abortion can also be considered if the parents so desire. Maternal life expectancy is not usually affected by hypochondrogenesis. Furthermore, there are no particular complications for the mother.
When should you go to the doctor?
Since hypochondrogenesis does not heal itself and in most cases the symptoms worsen, a doctor must be consulted in any case with this disease. This can avoid further complications. The sooner the doctor is consulted, the higher the probability of a cure. The affected person should consult a doctor if the child develops growth disorders and restricted bone structure. The bones often grow together, which can lead to restricted movement and, in many cases, severe pain.
Very short extremities can also indicate hypochondrogenesis and should always be examined by a doctor. Hypochondrogenesis can also lead to stillbirth in some cases. If the disease is diagnosed before birth, an abortion can take place. Since the disease can in many cases also lead to psychological problems in the mother or parents, a visit to a psychologist is advisable.
Treatment & Therapy
In the case of a genetic disease, therapies have so far not been possible. Therapy would have to start with the parents or the carrier of the autosomal dominant gene, but also with the fetus in the womb. Doctors are trying to develop gene therapy that replaces mutated genes with healthy ones, but this method is still only in the experimental phase.
It remains to be seen whether it will be used in the near future. The development of the fetus and embryo in the womb can be controlled from the outside by adding important vitamins and proteins, but collagen II is only produced inside the cell by the faulty gene itself. A supply and processing of artificial collagen II (such as insulin in diabetes) is not possible.
Prevention
Because it is a genetic modification, there is no prevention for this disease. However, during pregnancy tests, the parents’ genes are examined for mutations. If a change is detected, the doctor informs the parents. However, such genetic tests can also be carried out outside of pregnancy.
This gives parents an opportunity to discuss the extent to which they want to have a high-risk pregnancy. Geneticists, but also doctors, give high-risk parents intensive advice and explain all possible disorders to them. There may also be alternatives to getting pregnant yourself, such as adoption or artificial insemination.
Aftercare
There are no clear preventive and aftercare measures against the hereditary disease hypochondrogenesis. However, in connection with a pregnancy test, the doctor checks the genes of the parents for possible mutations. If there is a change, the parents will be informed immediately. They can then consider whether they want to enter into such a high-risk pregnancy or not.
Through intensive advice from doctors and geneticists, the affected parents learn all the important facts about the disease and the disorders associated with it. An alternative such as artificial insemination or adoption may be discussed. There is basically no targeted self-help for those affected.
During pregnancy, it is possible to specifically control the development of the fetus. This is possible with protein and vitamin supplements. However, it is not possible to cure the hereditary disease. Since the sick children are often stillborn, the parents think about an abortion. The associated upsets and discomfort can trigger depression.
That is why psychotherapeutic support is very important. Contacting other parents helps to cope with the situation and process the grief. To prevent recurrence of the disease, those affected should seek comprehensive genetic counseling when planning another pregnancy.
You can do that yourself
In most cases, hypochondrogenesis cannot be prevented directly. Parents can have various tests carried out during pregnancy in order to detect the disease at an early stage. Alternatively, artificial insemination can also be carried out in order to avoid the disease with the onset of foreign genetic material. Self-help methods are also generally not available to those affected.
During pregnancy, the development of the child can be controlled to a limited extent by the addition of proteins and vitamins, although this does not result in a complete cure for the disease. In many cases, the children are stillborn, so that parents may also consider an abortion.
Furthermore, hypochondrogenesis can lead to severe mental health problems or depression in parents and relatives. For this reason, psychological counseling and treatment by a psychologist should always be carried out in the case of the disease. Contact with other people affected can also answer questions and resolve possible psychological upsets. Genetic counseling should be carried out before another pregnancy to avoid the recurrence of hypochondrogenesis.