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Disease Profile

Absence of septum pellucidum

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset





Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable



Nervous System Diseases


The absence of the septum pellucidum is a rare condition that affects the structure of the brain. Specifically, a thin membrane called the septum pellucidum is missing from its normal position in the middle of the brain.[1] When it is missing, symptoms may include learning difficulties, behavioral changes, seizures, and changes in vision. Absence of the septum pellucidum is not typically seen as an isolated finding. Instead, absence of the septum pellucidum is associated with other conditions such as septo-optic dysplasia.[2] Treatment options for the condition vary depending on the underlying disorder. Diagnosis of absence of the septum pellucidum can be made through imaging such as an MRI. Symptoms of absence of the septum pellucidum typically present during childhood, but a diagnosis can also be made before an individual is born (prenatally).[3] If an individual is found to be missing the septum pellucidum, a search for an underlying disorder should be made.


The symptoms of absence of the septum pellucidum may vary, and it may be difficult to determine which symptoms are due to the underlying disorder and which ones are due to absence of the septum pellucidum. Symptoms that are common among people with absence of the septum pellucidum include learning disabilities, seizures, and behavioral changes. The septum pellucidum provides information to the rest of the body about how the body is doing. This information may include whether or not the body has received enough sleep or food, or whether the environment is safe.[4] Therefore, an absence of the septum pellucidum may cause an individual to feel hungry even when they are not or tired when they have had enough sleep. Some people with absence of the septum pellucidum do not grow very tall or have a high body mass index (BMI). This means that they have a higher weight than is typical for their height.[5]


Absence of the septum pellucidum can be caused by multiple factors depending on the underlying condition. Some people are born with or develop hydrocephalus, or a fluid buildup in the brain. If this condition goes untreated, the excess fluid can disintegrate the septum pellucidum. Absence of the septum pellucidum can also be the result of a genetic condition that is present in a baby at birth. Additionally, the septum pellucidum is connected to another brain structure called the corpus callosum, which is responsible for sending information between the two halves of the brain. Some people are born with a missing corpus callosum. People with a missing corpus callosum will also have a missing septum pellucidum.[1] 

Learn more

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

In-Depth Information

  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Absence of septum pellucidum. Click on the link to view a sample search on this topic.


  1. NINDS Absence of Septum Pellucidum Information Page. National Institute of Neurological Disorders and Stroke. February 2, 2016; https://www.ninds.nih.gov/Disorders/All-Disorders/Absence-Septum-Pellucidum-Information-Page.
  2. AJ Barkovich and D Norman. Absence of the Septum Pellucidum: A Useful Sign in the Diagnosis of Congenital Brain Malformations. American Journal of Roentgenology. February 1989; 152:353-360. https://www.ajronline.org/doi/pdf/10.2214/ajr.152.2.353.
  3. Garcia-Arreza A, Garcia-Diaz L, Fajardo M, Carreto P, and G Antiñolo. Isolated absence of septum pellucidum: prenatal diagnosis and outcome. Fetal Diagnosis and Therapy. 2013; 33(2):130-132. https://www.ncbi.nlm.nih.gov/pubmed/22572040.
  4. M Sarwar. The Septum Pellucidum: Normal and Abnormal. American Journal of Neuroradiology. October 1989; 10:989-1005. https://www.ajnr.org/content/10/5/989.full.pdf.
  5. C Traggiai and R Stanhope. Body mass index and hypothalamic morphology on MRI in children with congenital midline cerebral abnormalities. Journal of Pediatric Endocrinology & Metabolism. February 2004; 17(2):219-221. https://www.ncbi.nlm.nih.gov/pubmed/15055357.

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