This patient with past medical history of microcephaly, lymphedema and mild cognitive delay, was referred for retinal evaluation. Ophthalmological evaluation was notable for hyperopia and extramacular pigmentary changes with peripheral non-perfusion. The ERG disclosed significant rod and cone dysfunction suggestive of Retinitis Pigmentosa. However, genetic testing was negative. The patient was then referred to genetic counseling and given the presence of microcephaly, upslanting palpebral fissures, upturned and round nasal tip, history of lymphedema and pigmentary changes in the retina, he was thought to fit the phenotype for MCLID . Genetic testing was positive for KIF11 gene mutation confirming the diagnosis. Additionally, this mutation was not found in parental samples confirming a de novo mutation in this patient. The KIF11 gene encodes a protein called EG5, which is involved in microtubule sliding, mitotic spindle assembly and chromosome segregation. More recently was localized to the photoreceptors, which are considered modified cilia. As such, this findings suggest KIF11 mutations may be considered as part of the group of other ciliopathies such as Bardet Bied, Joubert, Alstrom and other pigmentary retinopathies.
Additionally, an interesting phenotypic overlap has been found between MCLID and FEVR patients, which will explained the peripheral non-perfusion found in this patient. This case highlights the importance of considering KIF11 mutations and MCLID in the screening of patients with retinal dystrophies and peripheral non-perfusion because other syndromic manifestations may be subtle.
Presentation Date: 06/02/2022
Issue Date: 07/01/2022