Clinical Characteristics
Ocular Features
A variety of nondiagnostic facial features are present at birth including hypertelorism, downward slanting lid fissures, proptosis, frontal bossing, and midface hypoplasia.
Systemic Features
Aortic aneurysms with or without dissection have been diagnosed as early as 1 year of age but may not be apparent until teenage years. Pectus deformities, joint hypermobility, and skin striae may be seen. Hypertrichosis, evidence of skeletal dysplasia such as hip dislocation, platyspondyly, phalangeal dysplasia, joint hypermobility, relative macrocephaly, dysplastic epiphyses of the long bones, and cervical spine instability are often present.
Genetics
Inheritance
This X-linked disorder is caused by a mutation in the BGN gene (Xp28). No male-to-male transmission has been reported although both sexes are affected.
Pedigree
X-linked dominant, mother affected
X-linked inheritance patterns result from mutations located on the X chromosome. Females have two X chromosomes of which only one carries a mutation in X-linked dominant disorders. This usually results in expression of the disease and women with a single mutation have the disorder caused by the mutation. Half of their offspring, male and female, will inherit the mutation. Men, with only one X chromosome, will always have the condition if they inherit the one with the mutation. Men would transmit it to all of their offspring. Without a modifying normal gene on a second X chromosome, X-linked dominant conditions are frequently lethal in such males. The result is a vertical transmission pattern, usually from female to female.
X-linked inheritance patterns result from mutations located on the X chromosome. Females have two X chromosomes of which only one carries a mutation in X-linked dominant disorders. This usually results in expression of the disease and women with a single mutation have the disorder caused by the mutation. Half of their offspring, male and female, will inherit the mutation. Men, with only one X chromosome, will always have the condition if they inherit the one with the mutation. Men would transmit it to all of their offspring. Without a modifying normal gene on a second X chromosome, X-linked dominant conditions are frequently lethal in such males. The result is a vertical transmission pattern, usually from female to female.