KIF11-related Microcephaly with Chorioretinopathy and Pachygyria: A Case Report of a De novo Start Codon Variant in an Indian Child

KIF11 encodes kinesin-11, a motor protein essential for mitotic spindle formation and chromosome segregation. We present a 2-year-7-month-old male with a de novo heterozygous start codon mutation in KIF11 (c.1A>G, p.?), leading to a diagnosis of KIF11 -related microcephaly with chorioretinopathy, lymphedema, and global developmental delay (OMIM #152950). The patient exhibited all described classical features along with pachygyria on MRI-challenging prior assumptions that cortical malformations are exclusive to TUBGCP6-related pathology with similar phenotype. The variant was classified as likely pathogenic (ACMG: PVS1, PM2, PM6) and is not reported in population databases. This case adds to the growing evidence that pachygyria can be part of the KIF11 phenotype and underscores the importance of integrating clinical, imaging, and genetic data for accurate diagnosis. Prenatal testing in a subsequent pregnancy was normal.