We still have much to learn about Smith-Kingsmore syndrome, and no two SKS individuals are alike, even those with the same MTOR variant. Features of SKS can vary in type and severity, and may evolve and change over time. Listed here are some of the common features we’ve identified through our global patient registry and discussions amongst the community. It has been put together by health professionals who have treated individuals with Smith-Kingsmore syndrome.
Behavioral
- Autism or autism-like traits, sensory processing disorder
- ADHD (attention-deficit/hyperactivity disorder)
- Anxiety
- Obsessive-Compulsive Disorder
- Self-harming behaviors
- Speech: delays in communication in both expressive and receptive language, non-verbal, distorted articulation. Some individuals can be late to start talking and may have a limited vocabulary while others remain nonverbal (but have intentional vocal sounds)
Neurologic
- Intellectual impairment/disability, varying from mild to severe
- Global developmental delays
- Sleep issues (insomnia, waking at night, sleep apnea)
- Seizures (including nocturnal focal epilepsy). It’s estimated ~40% of individuals with SKS have had at least one seizure. Many individuals require anti-epileptic medications for ongoing management.
- Low muscle tone (hypotonia), which can result in delayed developmental milestones such as rolling over, sitting, crawling, walking. While most many individuals with SKS can walk independently, some require mobility aids.
- Macrocephaly (large head size) / megalencephaly (large brain size) / ventriculomegaly (enlarged brain ventricles) / polymicrogyria (abnormal brain development before birth) / other brain abnormalities on MRI / rapid head growth first 6 months
- Hearing impairment due to damage to inner ear or to nerve pathways from inner ear to the brain; some individuals with SKS have benefitted from cochlear implants
- Cortical Visual Impairment (vision impaired due to the way the brain processes what the eyes see), which may be due to abnormalities in the brain rather than in the eyes
Physical
- Macrosomia at birth (large for gestational age)
- Accelerated growth first 18 months to 2 years
- Interoception (understanding the body’s signals/feeling sensations) and body temperature dysregulation: inability to determine if hungry/full, hot/cold, or overheating easily
- Decreased perspiration / heat intolerance
- Abnormal facial features – frontal bossing (prominent forehead), an open mouth appearance, a prominent and long philtrum (space between nose and upper lip), short nose with a flat nasal bridge, macrostomia (unusually large mouth), hypertelorism (wide-set eyes)
- Skin pigmentation / Blaschko lines / hypomelanosis / hypomelanosis of ito (lack of skin color) / Cafe au lait spots
- Delayed bone age (scan at 2 years were that of a newborn) / or slightly advanced bone age
- Accelerated growth first 18 months to 2 years
- Delayed bone age (scan at 2 years were that of a newborn) / or slightly advanced bone age
- Motor skill deficits due to low muscle tone, such as pincer grasp, writing and self-care (feeding, dressing, toileting)
- High threshold for pain
- Curly / wavy hair
Digestion/Gastrointestinal
- Digestive issues (abdominal pains, constipation, gastroesophageal reflux)
- Hyperphagia – abnormally increased appetite for food
SKS