Rare diseases: Von Hippel-Lindau syndrome
Von Hippel-Lindau syndrome (VHL) is a rare genetic disease. Affected persons have an increased risk of forming fluid-filled sacs (cysts) and developing certain types of tumours, both benign and malignant
It manifests itself most often around the age of 30, but can appear at any age, even in childhood.
Both sexes are affected equally.
It is a rare condition, with an estimated frequency of about 1 patient per 50,000 subjects.
Von Hippel-Lindau syndrome is caused by alterations (mutations) in the VHL gene
It is a tumour suppressor (oncosuppressor) gene involved in the control of cell growth and death and the regulation of blood vessel development.
Oncosuppressors prevent cells from growing and multiplying too rapidly or uncontrollably.
This is why, in the absence of the protein produced by the VHL gene or when this protein is altered, cells multiply uncontrollably and cysts and tumours form.
It is a hereditary condition transmitted in an autosomal dominant manner.
Von Hippel-Lindau syndrome occurs when only one of the two VHL genes is altered (mutated)
A normal copy of the gene is present but is not sufficient to reconstruct the message that has been altered by the mutated gene.
Consequently, a parent carrying a mutated copy of one of the two VHL genes has a 50% risk, at each conception, of having a child with Von Hippel-Lindau syndrome.
In approximately 80% of cases, the syndrome is inherited from a parent with Von Hippel-Lindau syndrome.
Typically, several people within the same household are affected by this disease.
However, the clinical manifestations within the same family can be very different.
In the remaining 20% of cases, the parents are not affected by Von Hippel-Lindau syndrome and it is therefore a de novo mutation, which means that the mutation occurred during the formation of the egg cell, the sperm cell or in the very early stages of embryonic development.
The mutation will therefore only affect that child and no other family member will be affected.
A person who has this mutation in his or her DNA is more likely to manifest certain types of tumours at a much earlier average age than when the same tumours usually occur.
The benign tumour most commonly associated with Von Hippel-Lindau syndrome is haemangioblastoma
When localised to the retina it is usually asymptomatic, but if it grows in certain retinal districts it can cause retinal detachment, oedema of the macula, glaucoma and loss of vision.
Central nervous system haemangioblastomas are generally located in the cerebellum, brainstem and spinal cord.
Compression can cause various symptoms: headache, vomiting, disturbance of sensitivity and loss of muscle coordination (ataxia).
Tumours of the inner ear occur in about 10% of individuals with Von Hippel-Lindau syndrome, which can cause hearing loss in one or both ears.
Renal, pancreatic and uro-genital organ cysts are very common.
These patients are also at high risk of developing tumours of the kidney and pancreas.
Some patients have pheochromocytoma, a renal tumour that produces hormonal substances capable of inducing very severe hypertension.
Diagnostic suspicion must arise at any age when there is a tumour associated with this disease, even more so if it appears early and if there are family members affected by Von Hippel-Lindau syndrome.
The search for mutations in the VHL gene confirms the diagnosis
A father or mother with Von Hippel-Lindau syndrome has a 50% chance of transmitting the mutation at each conception, regardless of the sex of the unborn child.
If the gene has been identified, it is possible to search for the specific mutation during pregnancy on a sample of chorionic villi or amniotic fluid, around X-XII and XV-XVII weeks gestational age, respectively.
Identifying the mutation during pregnancy allows us to know whether the foetus has inherited the mutation but does not allow us to predict the clinical evolution (and severity) of the syndrome in the life of the child to be born.
The treatment of this condition requires the joint intervention of several specialists depending on the clinical presentation.
It is essential to initiate a programme of surveillance for the appearance of tumour lesions that allows early surgical treatment, which is often decisive.
The occurrence of tumours cannot be prevented, however, surgical treatment can prevent tumour localisations from producing damage in vital organs or general complications.
A screening programme and regular check-ups are essential.
Prognosis is extremely variable depending on the clinical presentation.
As can be seen, much depends on the location of the tumour lesions and their extent.
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