TUBB2B and congenital fibrosis of the extraocular muscles: TUBB2B and TUBB3-related β-tubulinopathies can also present as disorders of axon growth and guidance, causing additional anomalies in axons innervating the oculomotor muscles, resulting in an eye-movement disorder termed as congenital fibrosis of the extraocular muscles (CFEOM; MIM: PS135700) [2].