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Participant 038

pontocerebellar hypoplasia, type 2D
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Female, age 3 with pontocerebellar hypoplasia, type 2D caused by changes in the SEPSECS gene

Date of Report

Nov 09, 2017


At birth, the patient had low muscle tone (hypotonia) and poor head control. She was initially able to breast feed, but stopped at the age of 7 months. At 8 months, an MRI showed abnormal brain findings (cerebellar atrophy). She was admitted to the hospital at the age of 10 months for sleep problems and abnormal breathing (stridor).

Currently the patient has developmental delay and still struggles with head control. She does recognize her mother and has a social smile, but appears to have vision impairment (cortical visual impairment). She also sweats a lot and needs a G tube for feeding. At times, she has low blood glucose levels (hypoglycemia). She recently has had seizures which are being controlled by medication.

Symptoms / Signs
  • Low muscle tone (severe muscular hypotonia)
  • Muscle weakness
  • Weak facial muscles (myopathic facies)
  • Poor head control
  • Impaired voluntary movements (dyskinesia)
  • Intellectual disability
  • Severe global developmental delay
  • Low blood glucose levels (hypoglycemia)
  • Difficulty growing after birth (failure to thrive)
  • Feeding difficulties
  • Poor appetite
  • Sleep disturbance
  • Irritability
  • Abnormality of specific brain regions (cerebellar hypoplasia and atrophy, cerebral hypomyelination, hypoplasia of the corpus callosum)
  • Abnormal electrical activity of the brain (EEG with persistent abnormal rhythmic activity)
  • Abnormality of the eye (abnormality of the retina and optic disc)
  • Repetitive eye movements (nystagmus)
  • Abnormality of vision (reduced visual acuity and cortical visual impairment)
  • Eyes turned outward (exotropia)
  • Drooped upper eyelids (ptosis)
  • Abnormal breathing (stridor)
  • Breathing dysregulation
  • Hand clenching
  • Decreased urine output
Current Treatments
  • Chloral hydrate – sleep problems
  • Domperidone and Omeprazole– reflux
  • Gabapentin – excessive sweating
  • Lamotrigine– seizures
Prior Treatments
  • Polyethylene glycol–  constipation
  • Melatonin –sleep problems
Considered treatments
Previously Considered Diagnoses
  • Congenital disorder of glycosylation
  • Fatty acid oxidation disorder
  • Metabolic condition
  • Mitochondrial disorder
  • Pompe disease
  • Spinal muscular atrophy
Other Photographs
Genetic Variants of Interest

Clinicians and researchers have identified the following genetic changes to be causing the patient’s symptoms:

Inheritance Pattern
Position (hg19)
DNA Change
Protein Change
Autosomal recessive
chr4:g.25146756dup & g.25146714C>T
c.808dupG & c.846G>A
p.Ala270GlyfsTer5 & p.Leu282=

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