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Participant 028

hypoglycemia and developmental delay
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Female, age 8, with very low blood sugar (hypoglycemia), developmental delay, and birth defects (tetralogy of Fallot, Chiari I malformation, tethered cord)

Date of Report

Aug 01, 2017


The patient was diagnosed with a heart defect (tetralogy of Fallot with pulmonary atresia) before she was born, which was repaired after birth. She was also found to have problems with the connection between her brain and spinal cord (Chiari I malformation) and the spinal cord itself (tethered cord).

She had episodes of hypoglycemia (low blood sugar) as a newborn with no cause found. At 3 years old, she had a severe hypoglycemic episode while sick with a virus. Since that time, it has been medically determined that if she does not eat every two to four hours, her blood sugar can drop into the 30-40s. It was thought that she may have a mitochondrial condition or glycogen storage disease, but testing for these conditions has not revealed a diagnosis. Glucagon is not effective in treating her hypoglycemia.

The patient has never been able to feed orally, therefore, she uses a g-tube for feeding and has a Nissen fundoplication to prevent reflux. She has a developmental delay and is nonverbal, but is making progress, especially with her motor skills. She also has vision issues (hyperopia, amblyopia) and wears glasses.

Symptoms / Signs
  • Hypoglycemia (low blood sugar)
  • Developmental delay
  • Intellectual disability
  • Nonverbal
  • Skull abnormalities (saggital craniosynostosis)
  • Brain abnormalities (hydrocephalus, mild dysgenesis of the corpus callosum, mild blunting of the rostrum, smaller than expected splenium & rostrum, small posterior fossa, paucity of periatrial white matter, mildly decreased white matter)
  • Outward wandering of the eye (alternating exotropia)
  • Farsightedness (hyperopia)
  • Lazy eye (amblyopia)
  • Discomfort by light in eyes (photophobia)
  • Dropped upper left eyelids (ptosis)
  • Hearing loss in left ear (conductive)
  • Recurrent ear infections (otitis media)
  • Weak cartilage in the walls of trachea and bronchial tubes (tracheomalacia, bronchomalacia)
  • Swallowing difficulties
  • Aspiration, microaspiration
  • Acid reflux (gastroesophageal reflux disease)
  • Wheezing
  • Rapid breathing (tachypnea)
  • Recurrent pneumonia
  • Sinus infections (acute sinusitis)
  • Asthma
  • Mildly enlarged liver (hepatomegaly)
  • Elevated liver enzymes and PT/PTT
  • Diminished muscle reflexes (hypoactive deep reflexes)
  • Elevated CPK muscle enzyme
  • Joint hypermobility
  • Constipation
  • Abnormal creases on palms and feet
  • Toe abnormalities (dysmorphic contours of the proximal phalanges of the 2nd, 3rd, and 4th digits, congenital fusion of the middle and distal phalanges of the 4th and 5th toe, hypoplasia of the right 4th metatarsal)
  • Fetal finger/toe tip pads
  • Leg length discrepancy
  • Flat feet
  • Underdeveloped (hypoplastic) toe nails
  • Aminoaciduria (sign of kidney dysfunction)
  • Mitochondrial depletion by muscle biopsy (33% of normal)
  • Stress-induced adrenal insufficiency
Current Treatments
  • Atrovent, Xopenex, Pulmicort- breathing problems
  • Cefdinir- infections
  • Frequent feeds, Glycosade- hypoglycemia
  • Levocarnitine- low carnitine levels
  • Coenzyme Q10- low carnitine levels
  • Miralax- constipation
Prior Treatments
Considered treatments
Previously Considered Diagnoses
  • Congenital disorder of glycosylation
  • Glycogen storage disorder
  • Microdeletion/duplication syndrome
  • Mitochondrial condition
Other Photographs
hypoglycemia and developmental delay
hypoglycemia and developmental delay
Genetic Variants of Interest

In 2022, clinicians and researchers identified the following de novo genetic change to be causing the participant’s symptoms. Additional possibilities are still being explored for this participant. Please reach out if you or someone you know has the same condition with some of the same symptoms.

Inheritance Pattern
Position (hg19)
DNA Change
Protein Change
chr17:24128508_ 25231047del
~1.181Mbp deletion

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


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