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Original research
Single amino acid variation in MAB21L1 is dominantly associated with congenital eye defects


Background Diagnosis of a genetic disease and determination of the causative molecular lesion rely on the availability of the disease-associated pedigrees. Microphthalmia is a congenital eye defect due to an insufficiently developed visual system; its prevalence is 1–3 in 10 000 live births.

Objective We analysed a pedigree exhibiting autosomal dominant inheritance of microphthalmia to determine the genetic lesion; used AlphaFold2 to predict the changes in the protein’s 3-Dimensional structure; and compared wild-type and variant proteins in cultured cells or Drosophila model was used to explore the cellular or developmental function of the encoded product.

Results We identified a novel missense variation, F52L, in MAB21L1 that is absent in population databases and present exclusively in the individuals diagnosed with microphthalmia in this pedigree. Common structural changes were predicted for the disease-associated variants clustered at amino acids 49–52, and these variant products were also predominantly trapped in the cytoplasm of cultured human lens epithelia. To recapitulate its dominant effect in development, we expressed the Drosophila homologue corresponding to MAB21L1F52L and caused malformation of sensory organs.

Conclusion Mutations at the residues 49–52 of MAB21L1 compromise eye development. We recommend including MAB21L1 in the genetic testing panel for congenital eye disorders.

  • Genetic Counselling
  • Congenital, Hereditary, and Neonatal Diseases and Abnormalities
  • Genetic Association Studies
  • Sequence Analysis, Protein

Data availability statement

Data are available on reasonable request.

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