The majority of cases of cerebro-costo-mandibular syndrome (CCMS) appear to occur sporadically (randomly), in people with no history of the condition in their family.^[2] However, familial cases have been reported (almost half of all cases), with both autosomal recessive and autosomal dominant inheritance described.^[4] To date, the underlying cause of CCMS has not been identified.

In a person with an autosomal recessive condition, both copies of the responsible gene in each cell must have a change (mutation). In these cases, the affected person usually inherits one mutated copy of the gene from each parent, both of whom are likely unaffected.

In a person with an autosomal dominant condition, having only one mutated copy of the responsible gene in each cell is enough to cause signs or symptoms of the condition. An autosomal dominant condition may be inherited from an affected parent, or the mutation may occur for the first time in the affected person. When someone with an autosomal dominant condition has children, each child has a 50% (1 in 2) risk to inherit the mutated gene.

Affected people from families suggesting autosomal recessive or autosomal dominant inheritance have overlapping features. In both groups, the severity varies, both among affected members of the same family and between families. The different patterns of inheritance seen support the likelihood that there is more than one genetic cause of CCMS.^[4]