Cleidocranial dysplasia (CCD) spectrum disorder is a skeletal dysplasia that represents a clinical continuum ranging from classic CCD (triad of delayed closure of the cranial sutures, hypoplastic or aplastic clavicles, and dental abnormalities), to mild CCD, to isolated dental anomalies without other skeletal features. Individuals with classic CCD spectrum disorder typically have abnormally large, wide-open fontanelles at birth that may remain open throughout life. Clavicular hypoplasia can result in narrow, sloping shoulders that can be opposed at the midline. Moderate short stature may be observed, with most affected individuals being shorter than their unaffected sibs. Dental anomalies may include delayed eruption of secondary dentition, failure to shed the primary teeth, and supernumerary teeth. Individuals with CCD spectrum disorder are at increased risk of developing recurrent sinus infections, recurrent ear infections leading to conductive hearing loss, and upper airway obstruction. Intelligence is typically normal.

Pyle disease is characterized by long bones with wide and expanded trabecular metaphyses, thin cortical bone, and bone fragility. Fractures are common in Pyle disease, and fracture lines usually go through the abnormally wide metaphyses, revealing their fragility (summary by Kiper et al., 2016).

Aspartylglucosaminuria is a lysosomal storage disorder characterized by developmental delay, intellectual disability, behavioral manifestations (hyperactivity in young children, anxiety and restlessness in adolescence, and apathy in adulthood), recurrent infections, musculoskeletal features, and characteristic craniofacial features (prominent supraorbital ridges, hypertelorism, periorbital fullness, short nose with broad nasal bridge, thick vermilion of the upper and lower lips, and macroglossia) that become more prominent with age. Additional neurologic manifestations can include seizures, poor balance and coordination, and progressive cerebral atrophy in adulthood. Macrocephaly is common. Musculoskeletal features include lordosis, scoliosis, and arthritis in adolescents and young adults; vertebral dysplasia and/or rib cage abnormalities; and progressive muscle wasting, joint contractures, bursitis, and osteoporosis in adulthood. Skin manifestations (facial seborrhea, rosacea, and angiofibromas), gastrointestinal manifestations, neutropenia, and thrombocytopenia occur in some individuals. The clinical manifestations of aspartylglucosaminuria worsen with age, and adults have progressive psychomotor decline.

Mulibrey nanism (MUL) is a rare autosomal recessive growth disorder with prenatal onset, including occasional progressive cardiomyopathy, characteristic facial features, failure of sexual maturation, insulin resistance with type 2 diabetes, and an increased risk for Wilms tumor (summary by Hamalainen et al., 2006).

X-linked intellectual disability-craniofacioskeletal syndrome is a rare, hereditary, syndromic intellectual disability characterized by craniofacial and skeletal abnormalities in association with mild intellectual disability in females and early postnatal lethality in males. In addition to mild cognitive impairment, females present with microcephaly, short stature, skeletal features and extra temporal lobe gyrus. In males, intrauterine growth impairment, cardiac and urogenital anomalies have been reported.

A distinct syndromic type of frontonasal malformation with characteristics of hypertelorism, wide nasal bridge, broad columella, widened philtrum, widely separated narrow nares, poor development of nasal tip, midline notch of the upper alveolus, columella base swellings and a low hairline. Additional features reported in some include upper eyelid ptosis and midline dermoid cysts of craniofacial structures and philtral pits or rugose folding behind the ears.