Muenke syndrome is characterized by considerable phenotypic variability; features may include coronal synostosis (more often bilateral than unilateral); synostosis of other sutures, all sutures (pan synostosis), or no sutures; or macrocephaly. Bilateral coronal synostosis typically results in brachycephaly, although turribrachycephaly (a "tower-shaped" skull) or a cloverleaf skull can be observed. Unilateral coronal synostosis results in anterior plagiocephaly. Other craniofacial findings typically include temporal bossing, widely spaced eyes, ptosis or mild proptosis, mild midface retrusion, and highly arched palate or cleft lip and palate. Strabismus is common. Other findings can include hearing loss, developmental delay, intellectual disability, behavioral issues, intracranial anomalies, epilepsy, ocular anomalies, brachydactyly, carpal and/or tarsal bone fusions, broad thumbs and great toes, clinodactyly, and radiographic findings of short and broad middle phalanges and/or cone-shaped epiphyses. Of note, some individuals who have the p.Pro250Arg pathogenic variant may have no signs of Muenke syndrome on physical or radiographic examination.

Cytochrome P450 oxidoreductase deficiency (PORD) is a disorder of steroidogenesis with a broad phenotypic spectrum including cortisol deficiency, altered sex steroid synthesis, disorders of sex development (DSD), and skeletal malformations of the Antley-Bixler syndrome (ABS) phenotype. Cortisol deficiency is usually partial, with some baseline cortisol production but failure to mount an adequate cortisol response in stress. Mild mineralocorticoid excess can be present and causes arterial hypertension, usually presenting in young adulthood. Manifestations of altered sex steroid synthesis include ambiguous genitalia/DSD in both males and females, large ovarian cysts in females, poor masculinization and delayed puberty in males, and maternal virilization during pregnancy with an affected fetus. Skeletal malformations can manifest as craniosynostosis, mid-face retrusion with proptosis and choanal stenosis or atresia, low-set dysplastic ears with stenotic external auditory canals, hydrocephalus, radiohumeral synostosis, neonatal fractures, congenital bowing of the long bones, joint contractures, arachnodactyly, and clubfeet; other anomalies observed include urinary tract anomalies (renal pelvic dilatation, vesicoureteral reflux). Cognitive impairment is of minor concern and likely associated with the severity of malformations; studies of developmental outcomes are lacking.

Mosaic variegated aneuploidy syndrome is an autosomal recessive disorder characterized by poor growth and variable phenotypic manifestations, such as facial dysmorphism and congenital heart defects, associated with mosaic aneuploidies resulting from defects in cell division (summary by Snape et al., 2011). See also MVA1 (257300), caused by mutation in the BUB1B gene (602860) on chromosome 15q15.