A case of Seckel syndrome (SS) accompanied by semilobar holoprosencephaly and arthrogryposis is reported from Erciyes University, Kayseri, Turkey. Seckel syndrome is a rare autosomal recessive disorder characterized by prenatal and postnatal growth retardation, microcephaly, and “bird-like” face with prominent, beak-like nose and micrognathia. A 1-day-old female newborn was admitted with dysmorphic features and feeding difficulties. The parents were consanguineous. In addition to typical features of SS, the baby had arthrogryposis, and cranial MRI showed semilobar holoprosencephaly, lissencephaly/pachygyria, dilated occipital horn of the lateral ventricle, hypoplasia of the frontal horn, non-cleavage of the basal ganglia and frontal lobe, and dysgenesis of the corpus callosum. Neuronal migration disorders should be investigated in infants born with facial characteristics of SS. 
COMMENT. Holoprosencephaly (HP) is presented as a new associated feature of SS. Based on grades of severity, this case is a semilobar form of HP. The mechanism of the facial dysmorphism in SS may be attributable to defective mesencephalic neural crest tissue formation.