Patient database
We searched PubMed® and HGMD® (Stenson et al., 2017) databanks (last query 05/2020) for reported patients with biallelic genetic variants inCEP120 and CC2D2A and detected 31 relevant publications. All genetic variants were manually curated and annotated using Ensembl Variant Effect Predictor (Ensembl release 100) (Yates et al., 2020), NCBI ClinVar and VarSome (Kopanos et al., 2019), matched with allele frequency data from the general population assessed via gnomAD v2.1.1. (Karczewski et al., 2020) and compiled using an identifier following the HGVS identification standard (den Dunnen et al., 2016). Patients reported in multiple publications were only included once in our database (if possible to detect) and patients with incomplete genetic or phenotypic information were not included. For each included patient, available phenotypic data were reviewed and where necessary adapted with following disease categories (Drivas et al., 2015): JBTS: All patients with hypoplasia of the cerebellar vermis and/or brain stem abnormalities and often intellectual disability; JSRD: JBTS with extra-CNS manifestations; Meckel-like syndrome (ML): lethality during the first months or years, characterized by cystic kidney disease, CNS malformation (typically DandyWalker malformation), polydactyly, and hepatic fibrosis; MKS: Similar to ML but uniformly perinatal lethal with occipital encephalocele being the predominant CNS malformation.