Clinical Characteristics

Most individuals present in childhood with developmental delay or growth failure.

Gross motor skills (the ability to crawl and walk), as well as speech usually take longer to achieve. Some children also have intellectual disability that can limit their ability to care for themselves independently.

Growth is slower and many individuals have short stature and a small head circumference. There may also be subtle differences in their facial appearance, which distinguish them from other family members. These characteristics include a long face with a narrow jaw, deep set eyes, prominent nose, dental crowding and a high mouth roof (palate).

About half of affected individuals have low muscle tone and weakness, which in some cases leads to high arches and problems with ambulation. Your doctor may recommend having nerve conduction studies (a test where they put small needles in your muscles to test how they react), which could show the presence of nerve damage (peripheral neuropathy).

Hearing loss and visual problems may develop with time and your doctor can help you monitor them and recommend treatment or aids, when appropriate.

A small number of individuals have endocrine problems; low thyroid levels (hypothyroidism), low growth hormone (likely contributing to their short stature), or they can go into puberty earlier (precocious puberty) or later (delayed puberty) than anticipated.

Some other even less commonly reported features include autism, seizures, tremors, feeding difficulties, constipation, chest deformities (pectus excavatum), abnormal back curvature (scoliosis), and strabismus.