SNP Shot: Genomic Insights

Cleidocranial dysplasia (CCD) is a genetic disorder primarily affecting bone and tooth development. The severity of CCD symptoms varies significantly, even among family members.

A hallmark of CCD is underdeveloped or missing collarbones (clavicles), hence the "cleido-" prefix. This leads to narrow, sloping shoulders that can be moved unusually close together, sometimes even meeting in the middle of the body. The skull's development is also delayed, characterized by late closure of skull sutures and larger-than-normal fontanelles ("soft spots"). While fontanelles usually close in early childhood, they can persist in individuals with CCD. Some may also have extra bones called Wormian bones within the skull sutures.

Individuals with CCD are often shorter than their family members. Other common features include short, tapered fingers with broad thumbs; flat feet; knock knees; short shoulder blades (scapulae); and scoliosis (spinal curvature). Facial characteristics may include a wide, short skull (brachycephaly), a prominent forehead, wide-set eyes (hypertelorism), a flat nose, and a small upper jaw.

Lower bone density (osteopenia) is common, increasing the risk of osteoporosis and fractures at a younger age. Women with CCD have a higher likelihood of needing a Cesarean section due to a narrow pelvis that can obstruct the baby's head during delivery.

Dental issues are prevalent in CCD, including delayed loss of baby teeth, delayed eruption of adult teeth, abnormally shaped teeth (peg-like), misaligned teeth and jaws (malocclusion), and extra teeth, sometimes accompanied by gum cysts.

Beyond skeletal and dental problems, individuals with CCD may experience hearing loss and are susceptible to sinus and ear infections. Some young children may have slight delays in motor skill development (crawling, walking), but their intelligence is not affected.

Inheritance:

CCD follows an autosomal dominant inheritance pattern. This means that only one copy of the mutated gene is needed to cause the disorder. Some individuals inherit the mutation from a parent with CCD, who may have mild symptoms or be undiagnosed. Other cases arise from new, spontaneous mutations in the gene, occurring in individuals with no family history of CCD.