The lack of success in identifying the molecular etiology of this condition is due to the heterogeneity and the variable expressivity of the condition, as well as the nonspecific phenotypes that overlap with other heritable connective tissue disorder and non-heritable disorders of connective tissue (1).
Ehlers-Danlos syndromes (EDS) are a clinically and genetically heterogeneous group of heritable connective tissue disorders characterized by joint hypermobility (JH), skin hyperextensibility, and tissue fragility (1).
Many patients with a heritable connective tissue disorder
have a high, narrow palate and/or dental crowding.
Heritable connective tissue disorders
such as type IV Ehlers-Danlos syndrome, Marfan syndrome, and type I osteogenesis imperfecta predispose patients to dissection.
This phenotype is generally more prevalent than other heritable connective tissue disorders
, although an accurate estimate is not possible.
(See Some Common Heritable Connective Tissue Disorders
for a description of some of the more common HDCTs.) Some Common Heritable Connective Tissue Disorders
Physicians and scientists have identified more than 200 heritable connective tissue disorders
Genetic factors involve family history and the presence of certain heritable connective tissue disorders such as Ehlers-Danlos syndrome, Marfan's syndrome, neurofibromatosis, and polycystic kidney disease.
Approximately 5% of all cases of intracranial aneurysm are associated with heritable connective tissue disorders, the most important being Ehlers-Danlos syndrome type IV, Marfan's syndrome, neurofibromatosis type 1, and polycystic kidney disease. These diseases manifest with vascular wall defects due to various etiologies; hence, patients with these diseases have a higher incidence of intracranial aneurysms than the average population.