Aarskog syndrome or Aarskog-Scott syndrome is a rare genetic condition resulting from an X chromosome mutation. The condition normally only occurs in males, although it is possible for females to have a less severe version of the condition. Aarskog syndrome affects a child's facial structure, their muscles and bones, genitals, and brain. It can also affect stature. The condition usually becomes apparent by the time a child reaches the age of three. There is no known cure for Aarskog syndrome.
Aarskog syndrome is inherited. A mutation of the FDG1 gene, known as the faciogenital dysplasia 1 gene, causes its development. Boys have just one X chromosome, so male children born to women who are carriers are likely to be affected. Girls have two X chromosomes. Even if they inherit one X chromosome with the mutation for Aarskog syndrome, it's likely that their other one will be normal and can compensate. For this reason, girls with the Aarskog syndrome genetic mutation will become carriers or develop the condition only mildly.
Children with Aarskog syndrome usually have distinctive facial features including a round face and eyes that are particularly wide-set or slanted in shape. The eyelids may have a sagging appearance and the nose can be unusually small or wide with slanting nostrils. People with Aarskog syndrome often have ears that fold down and a widow's peak. The condition can also cause a delay in tooth growth.
Aarskog syndrome causes various bone and muscle malformations. Many children with the condition are shorter than their peers and their chests may appear dented. A common location for bone and muscle malformation is in the hands, with shorter fingers than average, and possible "webbing." The little (pinky) fingers are often curled, and the palms of the hands may have just one crease instead of multiple creases.
Genital malformations are common in boys with Aarskog syndrome. Many children will have undescended testicles and an unusually-shaped scrotum. They may also have a lump called a hernia in the scrotum or groin area. People with Aarskog syndrome often have delayed puberty and reach sexual maturity later than other children.
Some children with the syndrome will also have a mild intellectual disability, although this is not always the case. People with Aarskog syndrome may have difficulty learning and delayed cognitive development. Aarskog syndrome can also cause behavioral difficulties, attention deficit hyperactivity disorder (ADHD), or impulsive behavior and issues with opposition.
Physical examination can help a doctor evaluate whether a child is likely to have Aarskog syndrome. They will check for typical facial features of the condition and examine the child's body for any bone, muscle, or genital malformations. If the doctor suspects Aarskog, they will order a genetic test to confirm the diagnosis by checking for mutations in the FGD1 gene. They may also order x-ray images of the child's head or other body parts to assess the severity of any bone abnormalities.
Although there is no cure for Aarskog syndrome, treatment can correct some of the physical issues the condition causes. Surgery can address bone malformations in the head or face, realign the teeth, correct genital malformations, and repair hernias in the groin or scrotum. A special operation can also help the testicles descend.
If the child has learning difficulties, they may require extra support in school. Behavioral difficulties such as ADHD may require input from a specialist. This can help parents, caregivers, and teachers develop strategies to support children with behavioral needs. Some children with Aarskog syndrome may need extra emotional support to address any physical problems; counselling can help some individuals.
There is no way to prevent a child from developing Aarskog syndrome, as the mutation responsible for the condition is present in their DNA from conception. However, women who believe they may be carriers can have genetic testing to confirm the presence of the X chromosome mutation.
Only around 50 cases have been confirmed worldwide. However, it is possible that some children with the condition are so mildly affected that they remain undiagnosed, so it's difficult to assess the total number of affected individuals accurately. Current estimations of the prevalence of Aarskog syndrome are around 1 in 25,000 or a little lower.
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