The term '3MC syndrome' encompasses 4 rare autosomal recessive disorders that were previously designated the Carnevale, Mingarelli, Malpuech, and Michels syndromes, respectively. The main features of these syndromes are facial dysmorphism that includes hypertelorism, blepharophimosis, blepharoptosis, and highly arched eyebrows, which are present in 70 to 95% of cases. Cleft lip and palate, postnatal growth deficiency, cognitive impairment, and hearing loss are also consistent findings, occurring in 40 to 68% of cases. Craniosynostosis, radioulnar synostosis, and genital and vesicorenal anomalies occur in 20 to 30% of cases. Rare features include anterior chamber defects, cardiac anomalies, caudal appendage, umbilical hernia (omphalocele), and diastasis recti (summary by Rooryck et al., 2011). Genetic Heterogeneity of 3MC Syndrome Also see 3MC syndrome-2 (3MC2; 265050), caused by mutation in the COLEC11 gene (612502), and 3MC syndrome-3 (3MC3; 248340), caused by mutation in the COLEC1 gene (607620).

Jawad syndrome (JWDS) is an autosomal recessive disorder characterized by congenital microcephaly, moderate to severely impaired intellectual development, and digital malformations including phalangeal joint swelling, clinodactyly, polydactyly, syndactyly, and total absence of nails (summary by Qvist et al., 2011).

Acrocapitofemoral dysplasia (ACFD) is an autosomal recessive skeletal dysplasia characterized by postnatal-onset disproportionate short stature, relatively large head, narrow thorax, lumbar lordosis, short limbs, and brachydactyly with small broad nails (Ozyavuz Cubuk and Duz, 2021).

An extremely rare type of spondyloepiphyseal dysplasia described in about 5 patients to date with clinical signs including short stature, peculiar facies with blepharophimosis, upward slanted eyes, abundant eyebrows and eyelashes, coarse voice, and short hands and feet.

ROR2-related Robinow syndrome is characterized by distinctive craniofacial features, skeletal abnormalities, and other anomalies. Craniofacial features include macrocephaly, broad prominent forehead, low-set ears, ocular hypertelorism, prominent eyes, midface hypoplasia, short upturned nose with depressed nasal bridge and flared nostrils, large and triangular mouth with exposed incisors and upper gums, gum hypertrophy, misaligned teeth, ankyloglossia, and micrognathia. Skeletal abnormalities include short stature, mesomelic or acromesomelic limb shortening, hemivertebrae with fusion of thoracic vertebrae, and brachydactyly. Other common features include micropenis with or without cryptorchidism in males and reduced clitoral size and hypoplasia of the labia majora in females, renal tract abnormalities, and nail hypoplasia or dystrophy. The disorder is recognizable at birth or in early childhood.