Skip Navigation
Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®

Enlarged parietal foramina

Reviewed March 2008

What is enlarged parietal foramina?

Enlarged parietal foramina is an inherited condition of impaired skull development. It is characterized by enlarged openings (foramina) in the two bones (parietal bones) that form the top and sides of the skull. This condition is due to problems with bone formation (ossification) within the parietal bones. The openings are symmetrical and circular in shape, with variable size ranging from a few millimeters to several centimeters wide. Parietal foramina are a normal feature of fetal development, but they usually close by the fifth month of pregnancy.

The area covering the parietal foramina is soft to the touch. Pressure applied to the openings can lead to severe headaches. People with enlarged parietal foramina usually do not have any related medical problems; however, scalp defects, seizures, and structural brain abnormalities have been noted in a small percentage of affected people. The risk of brain damage may be increased if any trauma is experienced in the area of the openings.

How common is enlarged parietal foramina?

The incidence of enlarged parietal foramina is estimated to be between 1 in 15,000 and 25,000 individuals.

What genes are related to enlarged parietal foramina?

Mutations in the ALX4 and MSX2 genes cause enlarged parietal foramina.

The MSX2 and ALX4 genes provide instructions for producing proteins called transcription factors, which are required for proper development throughout the body. Transcription factors attach (bind) to specific regions of DNA and help control the activity of particular genes.

Mutations in either MSX2 or ALX4 can disrupt a number of necessary cell functions. The cells involved in skull development seem to be particularly sensitive to these disruptions.

If the condition is caused by a mutation in the MSX2 gene it is called enlarged parietal foramina type 1. A mutation in the ALX4 gene causes enlarged parietal foramina type 2. There appears to be no difference in the size of the openings between enlarged parietal foramina types 1 and 2.

Related Gene(s)

Changes in these genes are associated with enlarged parietal foramina.

  • ALX4
  • MSX2

How do people inherit enlarged parietal foramina?

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.

In most cases, an affected person has one parent with the condition. A small number of cases may result from new mutations in the gene. These cases occur in people with no history of the disorder in their family.

Where can I find information about diagnosis or management of enlarged parietal foramina?

These resources address the diagnosis or management of enlarged parietal foramina and may include treatment providers.

  • Gene Review: Enlarged Parietal Foramina (
  • Genetic Testing Registry: Parietal foramina (
  • Genetic Testing Registry: Parietal foramina 1 (
  • Genetic Testing Registry: Parietal foramina 2 (
  • MedlinePlus Encyclopedia: Skull of a Newborn (

You might also find information on the diagnosis or management of enlarged parietal foramina in Educational resources and Patient support.

General information about the diagnosis ( and management ( of genetic conditions is available in the Handbook. Read more about genetic testing (, particularly the difference between clinical tests and research tests (

To locate a healthcare provider, see How can I find a genetics professional in my area? ( in the Handbook.

Where can I find additional information about enlarged parietal foramina?

You may find the following resources about enlarged parietal foramina helpful. These materials are written for the general public.

You may also be interested in these resources, which are designed for healthcare professionals and researchers.

What other names do people use for enlarged parietal foramina?

  • Catlin marks
  • cranium bifidum
  • foramina parietalia permagna
  • FPP
  • parietal foramina
  • PFM

For more information about naming genetic conditions, see the Genetics Home Reference Condition Naming Guidelines ( and How are genetic conditions and genes named? ( in the Handbook.

What if I still have specific questions about enlarged parietal foramina?

Ask the Genetic and Rare Diseases Information Center (

What glossary definitions help with understanding enlarged parietal foramina?

autosomal ; autosomal dominant ; bone formation ; cell ; DNA ; gene ; incidence ; inherited ; mutation ; ossification ; osteogenesis ; transcription ; trauma

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Fink AM, Maixner W. Enlarged parietal foramina: MR imaging features in the fetus and neonate. AJNR Am J Neuroradiol. 2006 Jun-Jul;27(6):1379-81. (
  • Mavrogiannis LA, Taylor IB, Davies SJ, Ramos FJ, Olivares JL, Wilkie AO. Enlarged parietal foramina caused by mutations in the homeobox genes ALX4 and MSX2: from genotype to phenotype. Eur J Hum Genet. 2006 Feb;14(2):151-8. (
  • Reddy AT, Hedlund GL, Percy AK. Enlarged parietal foramina: association with cerebral venous and cortical anomalies. Neurology. 2000 Mar 14;54(5):1175-8. (
  • Wilkie AO, Tang Z, Elanko N, Walsh S, Twigg SR, Hurst JA, Wall SA, Chrzanowska KH, Maxson RE Jr. Functional haploinsufficiency of the human homeobox gene MSX2 causes defects in skull ossification. Nat Genet. 2000 Apr;24(4):387-90. (
  • Wuyts W, Cleiren E, Homfray T, Rasore-Quartino A, Vanhoenacker F, Van Hul W. The ALX4 homeobox gene is mutated in patients with ossification defects of the skull (foramina parietalia permagna, OMIM 168500). J Med Genet. 2000 Dec;37(12):916-20. (
  • Wuyts W, Reardon W, Preis S, Homfray T, Rasore-Quartino A, Christians H, Willems PJ, Van Hul W. Identification of mutations in the MSX2 homeobox gene in families affected with foramina parietalia permagna. Hum Mol Genet. 2000 May 1;9(8):1251-5. (


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? ( in the Handbook.

Reviewed: March 2008
Published: February 1, 2016