X-kromosombunden hypofosfatemisk rakit
IDC-10: E83.3, E83.3B, E83.3D
Estimated occurrence5:100,000 live births. More common in females.
Mutation on the short arm of the X-chromosome (Xp22.11). X-linked dominant inheritance. The genetic mutation causes a blockage in the uptake of phosphate in the kidneys and insufficient activation of vitamin D in the kidneys, which affects bone production among other things.
X-linked hypophosphatemia (XLH) occurs at different levels of severity and symptom onset occurs at different ages. Skeletal symptoms such as poor height growth, genu varum or genu valgum (bow-legged or bandy-legged), pronounced lordosis (inward curve of spine) or stiffness and pain in the joints are common among children with XLH. Children lose 10-15 cm in height growth between the age of 1 and 3, but growth is subsequently normal. The loss of height growth during infancy leads to a shorter final height. Among adults, the disease can cause pain in the bones, poor leg alignment, problems in the knee joints, cracks in bones and impaired mobility.
Recurring abscesses at the roots of the teeth are common, despite the absence of caries. If XLH has not been treated during the period of tooth formation, there is a risk of enamel defects. Microscopic examination of a lost or extracted tooth can often confirm the diagnosis; the pulp cavity may be larger than normal and the tooth bone/dentine irregular. Increased predisposition for periodontal disease.
Advice on follow-up and treatment
- It is important that children with XLH see a children’s dental care specialist (pedodontist) as soon as the first teeth emerge.
- Dental treatment should primarily focus on protecting the enamel, since small caries damage such as cracks and superficial wear can rapidly cause infections in the pulp cavity.
- It is important to prevent damage to teeth by thorough oral hygiene, a good diet and sealing fissures in the masticating surfaces of molars. This applies to milk teeth and permanent teeth.
- At the first signs of grinding or pressing teeth, a mouth guard should be used at night and all damage to the enamel may need to be treated with a plastic coating.
- Despite treatment of the root, infections in the roots of the teeth do not always heal easily and the teeth affected must often be extracted, even with young patients.