Introduction and Objective:

Moebius Syndrome is a widely known rare congenital non-progressive neurological condition with external ophthalmoplegia and facial weakness due to sixth and seventh cranial nerve palsy. There are other conditions with similar and overlapping features, with variable involvement of other cranial nerves, frequently reported as ‘Moebius syndrome plus’ or ‘congenital facial syndrome’.

Case report: A non-consanguineous 10 year old Caucasian boy with an existing diagnosis of Moebius syndrome presented with facial diplegia, ptosis and ophthalmoplegia,  Later in childhood developing difficulties in fine motor skills, and frequent falls. Initially this was attributed to impaired vision and learning difficulty.

On examination at the age of 10, in addition to above features, he had wasting of hypothenar/thenar muscles, pes cavus and equinovarus deformity.

Neurophysiology studies showed axonal motor-sensory polyneuropathy. Genetic testing confirmed a heterozygous missense mutation in TUBB3.

Discussion: Moebius syndrome and CFEOM are classified under the heterogeneous congenital innervation dysgenesis syndrome group2. TUBB3 encodes a beta-tubulin protein that may be involved in neurogenesis, axon guidance and maintenance. Significant mutations in this gene cause CFOEM type 3 with progressive axonal and cranial neuropathy.

This case highlights two important principles, firstly the importance of clinical follow up for patients presenting in infancy with Moebius syndrome and careful clinical assessment in order to distinguish other phenotypes. Secondly, the availability of molecular genetic tests allows clinicians to determine the underlying cause so that the families can be given correct advice about prognosis and genetic implications.