A: The function of the cartilaginous rings of the trachea is to stabilize the trachea and keep it rigid while allowing the trachea to expand and lengthen when the person breathes. If the trachea was not supported in this way, it would simply collapse because of the pressure of the chest.
HCM remains the most common cardiovascular genetic disorder, occurring in at least 1 in 500 people in the general population. 7 HCM is a primary inherited disorder of the myocardium characterized by hypertrophy, usually of the left ventricle, in the absence of other loading conditions such as hypertension.
Prevalence. Spina bifida is the most common of the severe birth defects, occurring in one of every 1500-2000 live births. The most severe variant, myelomeningocele occurs in one of every 4000 live births. There is a definite genetic predisposition in that it is more common in families of Hispanic and European heritage.