X-Linked Hypophoshpatemia (XLH) is caused by one of several mutations of the PHEX gene, all of which cause XLH. There does not seem to be any correlation between the specific mutation and the severity of the symptoms experienced. Those with XLH generally exhibit the following:
Abnormal bone and tooth development, which may range from mild or moderate to severe.
Rickets that resists traditional Vitamin D therapy.
A few people with XLH exhibit no bone-related symptoms, and a study published in 1994 notes that it’s not uncommon for XLH to go undiagnosed in those with mild to moderate symptoms.
Lower limb deformities (bow or knock-knee)
Waddling gait
Short stature or declining growth rate
Spontaneous tooth abscesses
Bone pain
Muscle pain and weakness
SYMPTOMS SPECIFIC TO CHILDREN:
The child's wrists may be thicker than they should be, and when examined, the child's chest may have an array of bony beads, often called a rachitic rosary.
Teeth may be slow to appear, and the child may be very small for his or her age.
Rarely, there may be a problem with bone development in the head, and the physician should be able to recognize this development called craniosynostosis very quickly when measuring the size of the child's head.
As the child grows older and starts walking, parents may not recognize an abnormality in the child’s gait, but relatives or acquaintances who are only in infrequent contact may express concern.
The child's small stature may also be increasingly noticeable compared with his or her peers. Dental abscesses are a common complaint once teeth erupt because of faulty formation inside the tooth – not decay or trauma – and some children may feel different degrees of pain in their legs.
