Microphthalmia is not a mandatory finding in X-linked recessive syndromic microphthalmia caused by the recurrentBCORvariant p.Pro85Leu

Mutations in BCOR cause X-linked dominant and X-linked recessive forms of syndromic microphthalmia. By exome sequencing, we identified the recurrent BCOR mutation p.Pro85Leu in two brothers and their unaffected mother. While the older brother's phenotype completely fits the described phenotypic spectrum of X-linked recessive BCOR-associated Lenz microphthalmia syndrome, the younger brother showed developmental delay, microcephaly, and skeletal anomalies, but not the key feature of microphthalmia. In contrast to the previously published families, our findings demonstrate a large variability of BCOR-associated, syndromic phenotypes, indicating incomplete penetrance of p.Pro85Leu with regards to microphthalmia in males.