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What is Holoprosencephaly?

Mar 23rd, 2024 | by Samantha Berger, MS, OTR/L

Samantha Berger, MS, OTR/L

March 23rd, 2024

What is Holoprosencephaly?

To understand this condition, we need to understand the structure of the brain. The brain is separated into two halves, the left and right hemispheres, which remain connected to each other through a bundle of nerves known as the corpus callosum. The brain is further divided into separate lobes (the frontal, parietal, occipital, and temporal lobes), which all have important roles in processing information and commanding the body to do several different actions at once. Holoprosencephaly is a congenital condition that occurs when the developing brain does not separate into the left and right hemispheres. It occurs during fetal development (usually the second and third week) in the womb and can vary in severity and symptoms. Research estimates holoprosencephaly to be rare in live births, occurring in approximately 1 in 16,000 births.

What Causes Holoprosencephaly?

There are several known causes of holoprosencephaly; however, in many cases, determining the exact cause can be difficult. Below is a list of known conditions that have been linked to holoprosencephaly:

  • Genetic mutations:
    • SHH
    • SIX3
    • TGIF1
    • ZIC2
    • PTCH1
    • FOXH1
    • NODAL
    • CDON
    • FGF8
    • GLI2
  • Chromosomal abnormalities:
    • Trisomy 13
    • Trisomy 18
    • Triploidy
  • Genetic syndromes:
    • Hartsfield syndrome
    • Kallman syndrome two
    • Steinfeld syndrome
    • Smith-Lemli-Opitz syndrome
    • Stromme syndrome

What Are the Symptoms of Holoprosencephaly?

As holoprosencephaly can vary in severity and type, the condition’s symptoms can vary. This can include but is not exclusive to:

  • Developmental delay
  • Intellectual disability
  • Epilepsy and seizures
  • Small head (microcephaly)
  • Large head (macrocephaly)
  • Excessive fluid in their brain (hydrocephalus)
  • Facial abnormalities
  • Tooth abnormalities (single central incisor)
  • Cleft lip and/or palate
  • Problems regulating body temperature, heart rate and breathing
  • Feeding difficulties

What Are Some Treatment Options for Holoprosencephaly?

Unfortunately, there is no cure or primary form of treatment for holoprosencephaly. Treatment usually requires a coordinated effort of specialist doctors and therapists. These can include paediatricians, neurologists, endocrinologists, surgeons, occupational therapists, physiotherapists, and speech pathologists. With a specialist team approach, symptom management can be achieved to ensure a person with holoprosencephaly has a good quality of life and performs as many tasks as possible with as much independence as possible.

About the Author 

Samantha Berger is a paediatric occupational therapist at NAPA Center Los Angeles. When not engaging her clients through play, Samantha can be found balancing her love for ice-cream with spin or barre classes or trying to cuddle her dog, Cassidy, who would much rather have her personal space.

About NAPA Centre

In this blog, we discuss causes, characteristics, therapy and treatment options for Down syndrome.At NAPA Centre, we take an individualised approach to therapy because we understand that each child is unique with very specific needs. We embrace differences with an understanding that individualised programs work better. For this reason, no two therapeutic programs are alike. If your child needs our services, we will work closely with you to select the best therapies for them, creating a customised program specific to your child’s needs and your family’s goals. Let your child’s journey begin today by contacting us to learn more.

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