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Condition report · Neurological

CEBALID Syndrome (MN1)

Whole genome sequencing reads the MN1 gene for the specific changes near its end that cause CEBALID syndrome, a neurodevelopmental condition with distinctive facial features and brain differences.

A condition report looks for rare variants known to cause the conditions it covers.

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About this condition

A rare neurodevelopmental condition with distinctive facial and skull features, brain differences, hearing loss and speech delay. It is caused by specific changes near the end of the MN1 gene, usually arising new in the child.

CEBALID syndrome, also known as MN1 C-terminal truncation syndrome, is a rare neurodevelopmental condition. The name stands for craniofacial defects, dysmorphic ears, brain abnormalities, language delay and intellectual disability. Most people have mild to moderate intellectual disability and marked speech delay, along with an underdeveloped midface, small low-set ears and differences in brain imaging.

It is caused by specific changes near the end of MN1, which makes a transcription factor needed for palate and skull development. The changes produce a shortened protein that appears to act in a dominant way, rather than simply reducing the amount of MN1. Hearing loss is common, and some people have seizures or craniosynostosis, the early joining of skull bones.

Most cases arise new in the child. Genetic counselling and parental testing guide the recurrence risk, and prenatal and preimplantation testing are possible once the change is known in the family. Care is multidisciplinary, covering hearing, speech and language therapy, and developmental and educational support, with craniofacial and neurological review as needed.

The condition we analyse

Autosomal dominant

Caused by changes in the last part of the MN1 gene that produce a shortened protein, which appears to act in a dominant way. Cases typically arise de novo.

Signs and symptoms

Distinctive facial features, such as midface hypoplasia and small, low-set ears, with expressive language delay and mild to moderate intellectual disability are typical. Hearing loss, usually conductive or sensorineural, is common, and brain imaging may show structural differences such as rhombencephalosynapsis. Less often there are craniosynostosis or seizures.

What a diagnosis changes

Hearing assessment and support, speech and language therapy, and developmental and educational support, with craniofacial and neurological review as needed. Cases typically arise de novo, but genetic counselling and parental testing guide recurrence risk.

Genes analysed

Also known as

CEBALID; MCTT; MN1 C-Terminal Truncation Syndrome

MONDO:0032908OMIM 618774Orphanet 693549MedGen 1710973Sources: [1][2][3]

Why whole genome sequencing

CEBALID syndrome usually arises new in the child, so the key question for relatives is whether the change can be found in a parent.

Support for speech and hearing

Care is led by a team of specialists for developmental delay, feeding issues, seizures, hearing loss and speech and language needs. Alternative communication is used where speech is limited.

Recurrence risk when no parent carries it

If the change cannot be found in either parent, the risk to siblings is only slightly above that of the general population. Prenatal and preimplantation testing are possible once the change is known in the family.

References

  1. Mak CCY, Fung JLF, Lee M, Lin AE, Amiel J, Doherty D et al., 2020. MN1 C-Terminal Truncation Syndrome. GeneReviews
  2. Palma Milla C, Patricia PM, Lezana JM, Cruz J, Quesada JF, Vila S et al., 2023. A Novel Pathogenic Variant in the MN1 Gene in a Patient Presenting with Rhombencephalosynapsis and Craniofacial Anomalies, Expanding MN1 C-terminal Truncation Syndrome. Journal of pediatric genetics
  3. MN1 C-terminal truncation syndrome. MedlinePlus Genetics

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