Smith-Magenis Syndrome -Taylor Bug Kisses Foundation

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What is Smith-Magenis Syndrome

What is Smith-Magenis Syndrome?

Smith-Magenis Syndrome (SMS) is a micro-deletion in chromosome 17p11.2 or a mutation of the RAI1 gene. Smith-Magenis Syndrome is typically detected through a FISH analysis or G-banding. However, some of the new cost effective tests that have detected Smith-Magenis Syndrome are MLPA, qPCR and micro array CGH testing. There are currently only 600 people in the world diagnosed with Smith-Magenis Syndrome.

Positive attributes

Individuals with SMS are sweet, affectionate, helpful, joyful, enthusiastic, compassionate, determined, resilient, courageous, fun-loving, comical, amazing people with beautiful souls. They provide love to all those around them like no one else can! Their smiles fill rooms with sunshine and their laughter fills rooms with happiness. They are devoted, faithful, sincere and have unconditional love. They are nonjudgmental and they only see abilities in others. Their loving ways are immeasurable! They are living with Smith-Magenis Syndrome but they are not their syndrome.

Facial Features of Smith-Magenis Syndrome:

A flat mid-section of the forehead and bridge of nose, tented upper lip and down-turned mouth. Prominent and usually rosy cheeks (cherub-like as infants), broad and square shaped face, prominent jaw/extension of the mandible (usually more noticeable in older children and adults), deep set eyes, dark eyebrows that meet in the middle, flat and wide or disproportioned head.

Common Features present in 90-100% of individuals with SMS:

Sleep Disturbance **(frequent night awakenings, sleepiness in day/frequent napping, reduced REM sleep, early morning awake times  4:30-5:30 a.m.) due to an inverted circadian rhythm.  

**It is very important to note that while a common core group of features are seen in virtually all persons with SMS (sleep, behavior, self-injury, developmental delays, speech delays, motor delays, craniofacial and skeletal differences), SMS is variable and dependent on the 17p11.2 deletion size or if due to mutation of RAI1.

Developmental Delays in 75-100% of individuals with SMS:
  • Cognitive impairment/developmental delays.
  • Sensory integration disorder.
  • Self-injurious behaviors (i.e. head banging, slapping face, hand biting, picking at skin and sores, inserting foreign object into ears and nose or other body orifices, pulling off fingernails/toenails (older age)).
  • Generalized complacency and/or lethargy (in infancy).
  • Mouthing objects of hands, that persists beyond early childhood.
  • Maladaptive behaviors (i.e. hyperactivity, explosive outbursts, lack of impulse control prolonged tantrums, attention seeking (especially from adults), easy to be excited and easy to be distracted, aggressive, destructive).
  • Repetitive behaviors (i.e. hand squeezing or arm hugging when excited, quickly flipping pages of books/magazines).
Common Features present in 50-75% of individuals with SMS:
  • Hypotonia (low muscle tone).
  • Short stature (smaller chance in those with RAI1 mutation)
  • Small, short and wide hands and feet.
  • Scoliosis (smaller chance for those with RAI1 mutation).
  • Hearing loss (smaller chance of hearing loss for RAI1 mutation).
  • Flat feet.
  • Over responsive reflexes.
  • Open mouth posture, frequent drooling.
  • Ocular abnormalities.
  • Middle ear abnormalities (chronic ear infections).
  • Deep, hoarse voice.
  • Hyper nasal speech.
  • Dental anomalies.
  • Decreased sensitivity to pain.
  • Oral-sensory motor dysfunction (poor suck/swallow, decreased tongue strength & movement, and aversion to textures).
  • Wide gait.
  • Eye problems, including strabismus (an eye that turns in or out), myopia (nearsightedness), small corneas and/or iris anomalies.
  • Frequent constipation.
  • Hypercholesterolemia/Hypertriglyceridemia.
  • Abnormal EEG without seizures.
  • Signs of peripheral neuropathy.
  • Mild enlargement of the ventricular system in the brain.
  • Tracheobronchial problems.
  • Speech delay and articulation difficulty (little vocalization in infancy)
  • Velopharyngeal insufficiency (improper closing of soft palate muscle).
  • Teeth grinding.
  • Rocking motion.
Less common features present in 25-50% of individuals:
  • Seizures
  • Cardiac abnormalities (ventricular septal defect, atrial septal defect, tricuspid stenosis, mitral stenosis,  tricuspid and mitral regurgitation, mitral valve prolapse, aortic stenosis, pulmonary stenosis, tetralogy    of fallot, and total anomalous pulmonary venous return) smaller chance for those with RAI1 mutation.
  • Immune function abnormalities (low IgA, IgE and IgG).
  • Thyroid function
Occasional features present in 25% of individuals with SMS:
  • Renal/urinary tract abnormalities (less for those with RAI1 mutation).
  • Cleft lip/palate (less for those with RAI1 mutation).
  • Abnormalities in forearms.
  • Retinal detachment.
  • Obesity (usually in adolescence or adulthood) higher chance for those with RAI1 mutation.
Other features in infancy:
  • Happy disposition.
  • Delayed gross and fine motor skills.
  • Infrequent crying and vocalizing for age.

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Information on this site is intended for a general overview and for educational purposes. Information on this site is not intended to nor does it, constitute medical or other advice. Always consult with a physician before acting on any information you have read. Medical treatment for each individual should be in accordance to and followed by the patient's physician.