DDX11 and microcephaly: Bi-allelic mutations of the DDX11 gene cause Warsaw breakage syndrome (WABS), a rare pathology that is characterized by a complex spectrum of symptoms including pre- and post-natal growth defects, microcephaly, various degree of intellectual disability, heart defects, and at cytological level sister chromatid cohesion abnormalities, giving rise to an altered chromosome morphology [10].