Metronidazole (also known as Flagyl® or Metrolyl®) may cause acute liver failure in children with Cockayne syndrome and should be avoided. Please alert your doctors to this.
Health professionals can obtain further information from Dr. Brian Wilson
Any further drug reactions in this patient group should be reported to the regulatory authorities in your own country.
What is (photo-sensitive)
Trichothiodystrophy (TTD) is part of a group of aging diseases, including the Cockayne Syndrome. Trichothiodystrophy is the name for a lack of sulfur-rich proteins in hair and nails. The main feature of this condition is therefore to have extremely fragile and dry hair, which makes them particularly fragile. In addition, patients with TTD often have, but not always, the skin disorder ichthyosis that manifests itself in particular on the trunk and limbs. In ichthyosis, characterised by dry, thickened, scaly skin and remove ‘is varied, resulting in a dry, flaking skin. Often, redness and flaking of the skin can be seen from birth, and in severe cases are usually born as a collodion baby. Hypersensitivity to all kinds of infections occurs in half of the patients, but there is no indication of immune deficiency. Other symptoms that may also be found include intellectual decline, sunlight sensitivity, reduced growth, nail and dental disorders, fertility problems. All of these symptoms may occur in different combinations, which in the past led to indications such as BIDS, PBIDS, IBIDS and PIBIDS.
The letters stand for the following characteristics:
- Photosensitivity (sensitivity to light / UV radiation)
- Brittle hair
- Intellectual disability
- Decreased fertility
- Short stature
The spectrum of symptoms observed in TTD patients is very wide and ranges from a very mild form of disease-characterized by normal development and only fragile hair and ichthyosis to very severe cases characterized by high mortality at young age in combination with severe developmental disorders. About half of all patients with TTD have sensitivity to light or UV radiation (PBIDS and PIBIDS), as you see this in patients with Cockayne Syndrome. This is also briefly called photo-sensitive TTD today. Light that falls directly on the skin is very painful for these children and causes redness and blistering. This is because the mechanism that normally repairs DNA damage by UV light does not work well in the cells. In addition, there are a number of other phenomena that can also be found in patients with TTD. The following characteristics (symptoms) are a summary of more or less all features that can occur in different combinations and grades, so they do not have to be all present:
Trichothiodystrophy is caused by an error (mutation) in the hereditary material (genes). Mutations ensure that proteins, and thus the cells and organs, can no longer perform well. There are currently six genes known for the TTD syndrome, namely ERCC2, ERCC3, GTF2H5, RNF113A, MPLKIP and GTF2E2. Patients with mutations in the genes ERCC2, ERCC3 and GTF2H5 (either XPD, XPB or TTDA) are photo-sensitive, or sensitized to sunlight. Patients with mutations in RNF113A, MPLKIP (either TTDN1) and GTF2E2 are not. Photo-sensitive TTD has a defect in the NER system (DNA cleaning system). This is caused by a mutation (defect) in the genes. Because of the mutation in this gene, the damage in the DNA can not be restored. The damaged DNA cells are therefore degraded. They have no function anymore. This explains the early aging phenomenon at TTD.
Through the following research options, the diagnosis TTD can be confirmed:
• The diagnosis of TTD is best done by hair analysis. The patient's hair is analyzed for a lack of sulfur-rich proteins, the amount of the amino acid cysteine determines here. The hairs can also be viewed under a polarized light microscope, showing a typical light-dark bandering in the hair of a TTD patient.
• Genetic research: Currently, six genes are involved in TTD, namely ERCC2, ERCC3, GTF2H5, RNF113A, MPLKIP and GTF2E2. Because our knowledge of this disease is getting better, this list of genes will certainly expand in the future.
• Skin biopsy (a piece of skin): Through functional tests, the patient's skin cells can be examined for a defect in the DNA repair mechanism NER. Skin cells of photo-sensitive TTD patients are additional sensitivity to UV light. This test will not disclose to non-photo-sensitive TTD patients.
For more information go to: https://www.vermeulenlab.com/diagnostics/
TTD is recessively superficial and that means both parents must be the gene disorder (heterozygous carrier). Mutations in both alleles are therefore an absolute requirement for a patient's final diagnosis. When both parents are born of genetic defects, the parents have a 25% chance of having the child TTD, both parents have passed it on to the child. In addition, they have 50 percent chance that the child is a carrier of the defective gene.
How often does it occur?
The disease is estimated to be in 1 in a million people.
Trichothiodystrophy is not curable. The treatment is aimed at reducing complaints, supporting the child and the parents as well as possible and ensuring that the child develops as well as possible. Together with the skin doctor, the skin is treated with creams and ointments..