Hereditary diseases/congenital diseases/mutations
Phelan McDermid syndrome (deletion syndrome 22q13)
- Phelan-McDermid syndrome (PMS), also known as 22q13.3 deletion syndrome, is associated with severe mental retardation, lack of speech development and other symptoms, such as neuromuscular symptoms, with a 100% penetrance. The partial monosomy of the long arm of chromosome #22 and the associated loss of a gene copy of the ProSAP2/Shank3 gene triggers the symptoms typical of PMS. This gene codes for a synaptic structural protein of nerve cells that play an important role in the maturation of functioning synapses. The 22q13.3 Deletion Syndrome (Phelan-McDermid Syndrome)Phelan-McDermid syndrome data network:Integrating patient reported outcomes with clinical notes and curated genetic reports
Own studies for radiation sensitivity:
More than 20 patients with Phelan McDermid syndrome have already been studied and almost all of them showed a significantly increased radiation sensitivity (Increased Radiation Sensitivity in Patients with Phelan-McDermid Syndrome). The brain and blood lymphocytes are more sensitive to radiation in these patients, but there is evidence from our studies that not all cells in the body may be more sensitive to radiation.
Literature on clinical case reports/consequences of radiation:
A girl with Phelan McDermid syndrome develops an atypical teratoid/rhabdoid tumor of the central nervous system at the age of one year. At the age of 14 months, she was treated with radiation therapy with protons (28x1.64Gy within 48 days, total dose 45.9Gy) and suffered radiation necrosis with massive progressive deterioration until she had to be ventilated after 18 months. Description of a new oncogenic mechanism for atypical teratoid rhabdoid tumors in patients with ring chromosome 22
A boy with Phelan McDermid syndrome develops an atypical teratoid/rhabdoid tumor of the central nervous system at the age of four years, very similar to the case above. However, a radiosensitivity test is performed and radiotherapy is carried out with a significantly reduced fraction dose. The patient has no adverse radiation effects four years after the therapy (Increased Radiation Sensitivity in Patients with Phelan-McDermid Syndrome).
Conclusion regarding testing for radiation sensitivity:
Patients with Phelan McDermid syndrome who have an atypical teratoid/rhabdoid tumor must be tested for radiation sensitivity and the fraction doses adjusted accordingly!