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At a glance

A congenital syndrome with symmetrical bony skull defects.

Synonyms

Parietal Foramina Permagna; Parietal Foramina Magna; Hereditary Cranium Bifidum; Cranium Bifidum Occulta; 11p11.2 Deletion Syndrome; Foramina Parietalia Permagna; Fenestrae Parietales Symmetricae; Giant Parietal Foramina.

History

It was the American William M. Goldsmith in 1922 who chose the name Catlin Marks for this disorder. He observed this defect in 16 members of five generations in a family named Catlin.

Incidence

While small (diameter of <5 mm) parietal foramina are found in up to 70% of the population, large ones with a diameter of several centimeters are estimated to affect 1:15,000-20,000 live births.

Genetic inheritance

Autosomal dominant. Based on the genetic defect, three different types of Catlin Marks/Parietal Foramina Magna can be distinguished. Type 1 is caused by deletions in the MSX2 (Muscle Segment homeobox homologue 2) gene located on chromosome 5q35.2, Type 2 by deletions in the ALX4 (Aristaless-Like 4 Homeobox) gene on chromosome 11p11.2, and Type 3 by deletions in the PFM3 (Parietal Foramina 3) gene that has been mapped to chromosome 4q21-q23. Independent of the deletions, the lesions seem to be clinically indistinguishable, and while Type 1 and 2 have similar prevalences, Type 3 has only been described in one large Chinese pedigree.

Diagnosis

Most often, these lesions are asymptomatic and a coincidental finding on clinical examination or on a skull radiograph presenting as radiolucent defects. However, since inheritance is autosomal dominant, there is typically a family history present for this defect. Molecular genetic testing for MSX2 and ALX4 can be performed to confirm the diagnosis.

Clinical aspects

There is considerable variability among and within families suffering from this condition. The genetic defect results in abnormal membranous ossification around the parietal notch (normally completed by 20 weeks of gestation) and leads to large, symmetric, permanent, foramina, which are typically oval or round and located in the upper posterior corner of the parietal bone on both sides of the sagittal suture. In infants, the defect may be misinterpreted as an enlarged, persistent posterior fontanelle due to a single, large central parietal bone defect known as cranium bifidum, which can also include the anterior fontanelle. The fontanelles should be closed by no later than the end of the second year of life (anterior fontanelle is the last to close), but (small) residual frontal or parietal foramina may persist. As mentioned above, most lesions are asymptomatic. Occasionally, however, they can be associated with other pathologies, such as encephalocele, meningoencephalocele, myelomeningocele, dural arteriovenous malformations, dermal sinus, circumscribed scalp aplasia, meningeal, cortical, and vascular malformations of the posterior fossa (eg, persistent fetal vein), persistent falcine sinus with associated hypoplasia or atresia of the straight sinus, mesial occipital polymicrogyria, cleft palate, and spina bifida ...

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