Clinical features
Patients with PRR12 pathogenic variants often have global neurodevelopmental delay, impaired intellectual development, structural eye defects, and/or abnormality of vision. Eye abnormalities are often unilateral, showing marked variability in the type and severity, and include anophthalmia, microphthalmia, and coloboma, optic nerve and iris abnormalities. Other less commonly reported phenotypes include hypotonia, neuropsychiatric issues, heart defects, growth failure and kidney anomalies. Patients without developmental impairment have been reported.
Prevalence
PRR12 pathogenic variants are rare. Approximately 30 patients have been reported.
Genetic counselling
Mutations in PRR12 are inherited in an autosomal dominant manner, but to date all cases, except for one, resulted from a de novo mutation. Thus, the affected individuals usually represent sporadic cases, i.e., a single occurrence in a family. Parental studies should be performed to determine whether one parent carries the mutation. If the mutation is de novo, the recurrence risk for future pregnancies is considered low (likely <5%). Prenatal testing is possible, but the likelihood of recurrence in families who have had a de novo event in an affected child is considered low based upon the current knowledge.
PRR12