background participants

Participant 136

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Male, age 8 with global developmental delay, large head size (macrocephaly), low muscle tone (hypotonia), and seizures

Date of Report

Jul 10, 2019


Shortly after birth, the participant was found to have gastroesophageal (acid) reflux and low muscle tone (hypotonia). His growth was normal except for a large head size (macrocephaly).

At 2 months old, it was noted that he had cataracts and he underwent surgery before 1 year old. He was also found to have global developmental delay, fine motor delays, and communication delays. He started having seizures just before age 6.

The participant has an older sister with a similar medical history. In early infancy, she was noticed to have low muscle tone (hypotonia), global developmental delay, and a larger head size (macrocephaly). She also has communication delays and seizures.

Symptoms / Signs

Shared symptoms:

  • Global developmental delay
  • Expressive and receptive language delay
  • Intellectual disability
  • Autism
  • Seizures
  • Large head size (macrocephaly)
  • Low muscle tone (generalized hypotonia)
  • Increased reflexes (generalized hyperreflexia)
  • Single crease on palm of hand (single transverse palmar creases)
  • Webbed 2nd and 3rd toes (2-3 toe syndactyly)
  • Bent 5th toe (clinodactyly of the 5th toe)

Brother only:

  • Cataracts
  • Close-set eyes (hypotelorism)
  • Short fingers and toes (brachydactyly)
  • Abnormal brain activity (multifocal epileptiform discharges, EEG with generalized slow activity)
  • Aggressive behavior

Sister only:

  • Upslanting eyes (upslanted palpebral fissures)
  • Difficulty walking (gait disturbance, spastic gait)
  • Movement abnormalities (cogwheel rigidity)
  • Abnormal MRI findings (hyperintensity of cerebral white matter)
  • Mood swings
  • Irritability
Current Treatments
  • Occupational, physical, and speech therapy
Prior Treatments
Considered treatments
Previously Considered Diagnoses


  • Metabolic condition


  • Angelman syndrome
  • Fragile X syndrome
  • Krabbe disease
  • Microdeletion/duplication syndrome
  • Prader-Willi syndrome
Other Photographs
Genetic Variants of Interest

Clinicians and researchers are investigating the following genetic changes to see if they are causing the participants’ symptoms:

Inheritance Pattern
Position (hg19)
DNA Change
Protein Change
Autosomal recessive
Chr14:35513595_ 35521682; Chr14:35546986_ 35556772
8kb deletion; 9.7kb deletion

If this participant sounds like you or someone you know, please contact us!


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