Here, we show that mutations in CSPP1, which encodes a core centrosomal protein, are disease causing on the basis of the independent identification of two homozygous truncating mutations in three consanguineous families (one Arab and two Hutterite) affected by variable ciliopathy phenotypes ranging from Joubert syndrome to the more severe Meckel-Gruber syndrome with perinatal lethality and occipital encephalocele.
We report a monozygotic twin with severe NTDs (occipital encephalocele and myelomeningocele) and a shared de novo, likely truncating, variant in SMARCC1.
Reviewing the clinical data on patients with sequence variants in the tectonic genes TCTN1-3 reveals that all of them have a neurological phenotype with vermis hypoplasia or occipital encephalocele associated with severe intellectual disability in the surviving patients.
In addition, we identified five rare deletions and two duplications of uncertain significance including a rare intragenic heterozygous in-frame WDR63 deletion in a fetus with occipital encephalocele.
Identification of COL18A1 mutations in individuals with a Lennox-Gastaut phenotype and anterior polymicrogyria but lacking the classical occipital encephalocele expands the COL18A1 clinical spectrum.
Insights into the physiological function of collagen XVIII/endostatin have recently been obtained through the identification of inactivating mutations in the human collagen XVIII/endostatin gene (COL18A1) in patients with Knobloch syndrome, characterized by age-dependent vitreoretinal degeneration and occipital encephalocele.
Other malformations associated with MKS3 include cystic changes in the liver, polydactyly, and brain abnormalities (occipital encephalocele, hydrocephalus, and Dandy Walker-type cerebellar anomalies).