Common Features

Photo of boy with Smith-Kingsmore syndrome smiling, eating cake

People who have Smith-Kingsmore syndrome often show symptoms in very early childhood, sometimes at birth and within the first six months of life. They often have medical challenges, and typically have developmental delays (not achieving developmental milestones such as rolling over, sitting up, walking, or talking on time). These are often the first noticeable symptoms and are what prompt families to start down the diagnostic journey. In spite of the medical and developmental issues, people with Smith-Kingsmore syndrome tend to be easily amused and have a sweet disposition.

There are many symptoms and features that are thought to be part of Smith-Kingsmore syndrome. Some of the characteristics occur more frequently than others, and because there is great variability, not every person will have each of these. In the lists below “Common Features Reported” appear to occur more frequently than “Other Features Reported”, however as research progresses, the formal description of Smith-Kingsmore syndrome will change. Features documented or reported by families to date include the following:

Common Features Reported:
Digestion / Gastrointestinal
  • Digestive issues (abdominal pains, constipation, loose stools)
  • Food intolerances / eczema
  • Food Protein-Induced Enterocolitis Syndrome (FPIES)
Brain / Neurologic
  • Arachnoid cyst / retro cerebellar cyst
  • Delayed myelination and white matter abnormalities
  • Global developmental delays
  • Hydrocephaly / Large Ventricles / Ventriculomegaly
  • Intellectual disability (may be severe, moderate or mild)
  • Macrocephaly / megalencephaly / rapid head growth first 6 months
  • Non verbal / speech anomalies – delayed or absent speech, distorted articulation
  • Seizures (including nocturnal focal epilepsy)
  • Skill loss (say word once and then “forget”, learn new physical skill, then lose)
  • Sleep issues (insomnia, waking at night, sleep apnea)
Behavior / Psychiatric
  • Happy demeanor (smile and laugh a lot)
  • Self-stimulatory behavior / stimming / repetitive movement (bouncing, spinning, clapping, banging, hand tapping, repeating sounds)
  • Sensory issues (mouthing objects, hands in mouth)
  • Teeth grinding
  • Curly / wavy hair
  • Dysmorphic facial features
    • frontal bossing, tall forehead, downslanting palpebral fissures, bitemporal narrowing, an open mouth appearance, a prominent and long philtrum, flat nasal bridge, macrostomia, hypertelorism, and a short nose with a depressed nasal bridge
    • or large forehead, macrocephaly, triangular face, pointed chin
    • or face without a constant pattern
  • Feeding difficulties
  • Glue ear (resolved / mostly resolved by grommets)
  • High arched roof of mouth
  • Hypotonia (“floppy”, low muscle tone)
  • Macrosomia at birth (large for gestational age)
  • Motor skills deficits (unsteady walking, late walking, lacking hand skills, poor motor planning)
  • Poor immune system / recurrent chest infections, bronchiolitis
  • Vision issues (cortical visual impairment, myopia, raised optic nerves, retina dysfunction)
Other Features Reported:
  • Accelerated growth first 18 months to 2 years
  • Aversion to touch
  • Birth issues (breech presentation, premature, asphyxia / severe asphyxia at birth)
  • Bites finger
  • Cataplexy
  • Club foot
  • Decreased perspiration / heat intolerance
  • Delayed bone age (scan at 2 years were that of a newborn) / or slightly advanced bone age
  • Failure to thrive
  • Short stature (but now grown into his body)
  • Single palmar crease on one hand
  • Small hands and feet
  • Tongue and lip tie