Adult separation anxiety disorder affects roughly 7% of adults. It has also been reported that the clinically anxious pediatric population are considerably larger. For example, according to Hammerness et al. (2008) SAD accounted for 49% of admissions.Research suggests that 4.1% of children will experience a clinical level of separation anxiety. Of that 4.1% it is calculated that nearly a third of all cases will persist into adulthood if left untreated. Research continues to explore the implications that early dispositions of SAD in childhood may serve as risk factors for the development of mental disorders throughout adolescence and adulthood. It is presumed that a much higher percentage of children suffer from a small amount of separation anxiety, and are not actually diagnosed. Multiple studies have found higher rates of SAD in girls than in boys, and that paternal absence may increase the chances of SAD in girls. See also
Homesickness
Stranger anxiety

References
External links
The Strange Situation: Window on a Childs Past and Future
Are you gonna leave me? Separation anxiety is associated with increased amygdala responsiveness and volume
Ulnar dimelia, also referred to simply as mirror hand, is a very rare congenital disorder characterized by the absence of the radial ray, duplication of the ulna, duplication of the carpal, metacarpal, and phalanx bones, and symmetric polydactyly. In some cases surgical amputation is performed to remove the duplicate carpals, metacarpals and phalanges. As of 2015, approximately 70 cases have been recorded in the medical literature. Bone deformity may also accompany nervous and arterial anomalies in some cases due to the duplication of the ulnar nerve, the presence of abnormal arterial arches, the duplication of the  ulnar artery, the shortening of the radial nerve, and the absence of the radial artery. The diagnosis of ulnar dimelia is based on laboratory tests of frontal and sagittal planes in individuals suspected of the condition. There are two types of ulnar dimelia noted in medical journals: Type 1 ulnar dimelia entails one lunate and one trapezoid bone as well as one index finger, while type 2 ulnar dimelia has two lunate and two trapezoid bones as well as two index fingers. The American Society for Surgery of the Hand and the International Federation of Societies for Surgery of the Hand classified ulnar dimelia in the third group of congenital hand deformities in accordance with the characteristics proposed in the Swanson classification (1976). References
Tomaszewski, Ryszard; Bulandra, Andrzej (2015). "Ulnar dimelia-diagnosis and management of a rare congenital anomaly of the upper limb". Journal of Orthopaedics. 12 (Suppl 1): S121–S124. doi:10.1016/j.jor.2015.01.027. PMC 4674541. PMID 26719621. Namdev, Rupesh.