Key features of the Stankiewicz-Isidor syndrome are neurodevelopmental impairment, and more especially intellectual disability, and multisystemic congenital malformations.
In the original study, all subjects exhibited developmental delay (DD) or ID and had variable dysmorphic features, among which low-set ears, hypertelorism, and retrognathia or microretrognathia were the most frequent findings.
Almost all individuals had additional neurological features, including abnormal behavior (autistic features or hyperactivity), hypotonia, or epilepsy (seizure disorder, reflex seizures, or tonic convulsion).
Brain imaging showed abnormalities in two out of six subjects tested (pineal cyst, cerebral atrophy, and periventricular hypomyelination).
Almost all subjects had congenital anomalies, including atrio- or ventriculoseptal defect, patent ductus arteriosus, single or dysplastic kidney, hydronephrosis, or genital anomalies (hypospadias, cryptorchidism).
Half of the affected individuals had neonatal onset feeding difficulties associated with growth failure and requiring gastrostomy tube feeds in most cases.
Ophthalmologic anomalies were very frequent and included strabismus, vision loss, and coloboma.
Half of the affected individuals had skeletal abnormalities (bilateral 2-3 toe syndactyly, thumb agenesis or hypoplasia) and/or microcephaly.