1:160 000 - 200 000 live births
Cystinosis is caused by a mutation in the so-called CTNS gene on chromosome 17. This mutation causes an amino acid, cystine, to accumulate in the lysosomes of the cells. This high concentration of cystine is harmful and causes cell function to deteriorate and/or causes cells to die. Certain organs such as the kidneys, the eyes and thyroid, are particularly sensitive to elevated levels of cystine. The disorder is inherited autosomal recessively.
There are three forms of the condition: Nephropathic cystinosis (also called infantile), intermediate cystinosis (a juvenile form) and the third form, nonnephropathic cystinosis occurs exclusively in adults.
The children are born healthy and appear generally normal during the first months. Impaired kidney function eventually leads to severe kidney failure. Excessive urination and thirst commonly lead to evaluation and diagnosis. Kidney damage may result in the need for dialysis or kidney transplantation. The electrolyte balance is affected. The eyes and vision may be affected by storage of cystine crystals in the cornea and retina. Growth disorders are common as well as weak muscles. The function of the thyroid gland may be impaired (hypothyroidism) and puberty may be delayed and/or stop.
In non-nephropathic cystinosis the only symptoms are from the eyes. Today, cystinosis may be treated with medications (Cysteamine®, Cystagon). Treatment may also be required in the form of thyroid hormones, growth hormones and sex hormones as well as ensuring that the child receives adequate amounts of fluids, electrolytes and nutrition. Many have very high energy requirements, which means that they need to eat a lot and often.
Sucking, chewing and swallowing difficulties occur. The need for energy and liquids are extensive both day and night. Enteral feeding is common and sometimes necessary to ensure that the child’s nutritional requirements are met. Enamel disturbances are common. A side effect of some medications is a bad breath.
- Early contact with dental services for intensified prophylactic care and oral hygiene information is essential. Medication and frequent eating and drinking increase the risk of caries.
- Dental development is checked up by dentist who is familiar with deviating growth pattern and as need arises consult orthodontist.
- Feeding and swallowing difficulties are investigated and treated by a specialist team at the hospital or multidisciplinary treatment center.
- The rare disease database of the Swedish National Board of Health and Welfare.
- The MHC database - The Mun-H-Center database on oral health and orofacial function in rare diseases.
- The Documentation from the Ågrenska national competence centre for rare diseases.
- Bassim CW, Gautam P, Domingo DL, Balog JZ, Guadagnini JP, Gahl WA, Hart TC. Craniofacial and dental findings in cystinosis. Oral Dis. 2010 Jul;16(5):488-495.