Abstract: Objective To explore the clinical features and genotypes of Adams-Oliver syndrome type 2 (AOS 2 ) caused by mutation of DOCK 6 gene. Methods The clinical data of AOS 2 in a child were retrospective analyzed, and related literature was reviewed. Results The female child had developmental retardation since childhood. At 6 months of age, the child had convulsions, small head circumference and local telangiectasia in the bilateral thigh skin. Brain MRI showed multiple calcifications in both ventricular walls and subependymal layer, accompanied by paraventricular demyelination, brain dysplasia, mild atrophy of bilateral hippocampus, and abnormal signal in right temporal and occipital lobe. Genetic testing revealed the compound heterozygous mutations of c. 3069 _ 3069 del and c. 5220 + 1 G>A in the DOCK 6 gene of the child, which were respectively from the parents with normal phenotype. Both mutations had not been reported before and were pathogenic variants. Conclusion The newly discovered AOS 2 pathogenic gene expands the DOCK 6 gene variation spectrum.

Key words: Adams-Oliver syndrome type 2; DOCK 6 gene; clinical phenotype