What characteristics do patients with a change in the ZIC1 gene have in common?
Many children with ZIC1–related syndrome have an unusual skull shape. This is due to early fusion of the cranial sutures, which are the gaps between the skull bones. Typically the sutures that prematurely fuse in this syndrome are the coronal sutures, which run from ear to ear. The medical term for this is bicoronal craniosynostosis. However, other cranial sutures can also be affected. In bicoronal craniosynostosis the forehead is often high and the back of the head is flatter than usual (brachycephaly). Head size can be small in some cases (microcephaly).
There is often delay in acquiring the general developmental milestones (such as learning to walk and talk). Later this is associated with learning difficulties, which can be variable, ranging from mild to severe. Some children may have autistic features. Behavioural features have also been reported.
Many children with ZIC1–related syndrome have alterations in the way the brain is formed that are detected on brain scan. In particular, these are alterations in a part of the brain called the corpus callosum and also the cerebellum and the pons.
What other health implications may be associated with a ZIC1 gene change?
- Some children may be born with spine abnormalities such as spina bifida or tethering of the spinal cord.
- Some may develop a curvature of the spine (scoliosis).
- Around half of children have a squint and/or a droopiness of the eyelid (ptosis).
- Occcasionally seizures have been reported.
- Feeding difficulties have also been reported in some cases.
What may a ZIC1 gene change mean for the future of my child?
Most individuals with ZIC1-related syndrome have some degree of developmental delay and learning difficulty but this varies widely. At the mildest end of the spectrum there may be mild learning difficulties, whereas the most severely affected individuals may not be able to walk unassisted or to acquire speech, leading to substantial dependency in care. At present we cannot be clear about how the severity of the developmental issues relates to the exact gene change. If your child has craniosynostosis, they will need monitoring for this and it is possible they may need one or more operations to correct this.