Gabriele-de Vries syndrome is characterized by mild-to-profound developmental delay / intellectual disability (DD/ID) in all affected individuals and a wide spectrum of functional and morphologic abnormalities. Intrauterine growth restriction or low birth weight and feeding difficulties are common.

Koolen-de Vries syndrome (KdVS) is characterized by congenital malformations, developmental delay / intellectual disability, neonatal/childhood hypotonia, epilepsy, dysmorphisms, and behavioral features. Psychomotor developmental delay is noted in all individuals from an early age.

NCBI's Gene resources include collections of curated nucleotide sequences used as references, sequence clusters to predict and study homologs, and various databases and tools for the study of gene expression.

Chromosomes are long strands of a chemical substance called deoxyribonucleic acid (DNA). A DNA strand looks like a twisted ladder. The genes are like a series of letters strung along each edge. These letters are used like an instruction book.