This suggests there may be some genetic heterogeneity in this disease.A mutation in the gene encoding the type III sodium dependent phosphate transporter 2 (SLC20A2) located on chromosome 8 has been reported. Biochemical evidence suggests that phosphate transport may be involved in this disease.Two other genes have been associated with this condition: PDGFB on chromosome 22 and PDGFRB on chromosome 5. These genes are biochemically linked: PDGFRB encodes the platelet-derived growth factor receptor β and PDGFB encodes the ligand of PDGF-Rβ. These genes are active during angiogenesis to recruit pericytes which suggests that alterations in the blood brain barrier may be involved in the pathogenesis of this condition.A fourth gene associated with this condition is XPR1. This gene is the long arm of located on chromosome 1 (1q25.3).Another gene that has been associated with this condition is MYORG. This gene is located on the long arm of chromosome 9 (9p13.3). This gene is associated with an autosomal recessive inheritance pattern in this condition.Another gene junctional adhesion molecule 2 (JAM2) has been associated with an autosomal recessive form of this condition. Other genes that have been associated with this condition are Junctional adhesion molecule C (JAM3) and Occludin (OCLN). Pathology
The most commonly affected region of the brain is the lenticular nucleus and in particular the internal globus pallidus. Calcifications in the caudate, dentate nuclei, putamen and thalami are also common.
Diagnosis
A doctor might suspect dissociative fugue when people seem confused about their identity or are puzzled about their past or when confrontations challenge their new identity or absence of one. The doctor reviews symptoms and does a physical examination to exclude physical disorders that may contribute to or cause memory loss. Sometimes dissociative fugue cannot be diagnosed until people return to their pre-fugue identity and are distressed to find themselves in unfamiliar circumstances, sometimes with awareness of "lost time". The diagnosis is usually made retroactively when a doctor reviews the history and collects information that documents the circumstances before people left home, the travel itself, and the establishment of an alternative life. Functional amnesia can also be situation-specific, varying from all forms and variations of traumas or generally violent experiences, with the person experiencing severe memory loss for a particular trauma. Committing homicide; experiencing or committing a violent crime such as rape or torture; experiencing combat violence; attempting suicide; and being in automobile accidents and natural disasters have all induced cases of situation-specific amnesia (Arrigo & Pezdek, 1997; Kopelman, 2002a). As Kopelman (2002a) notes, however, care must be exercised in interpreting cases of psychogenic amnesia when there are compelling motives to feign memory deficits for legal or financial reasons. However, although some fraction of psychogenic amnesia cases can be explained in this fashion, it is generally acknowledged that true cases are not uncommon.