For example, an egg or sperm cell may gain an extra copy of the chromosome. If one of these atypical reproductive cells contributes to the genetic makeup of a child, the child will have an extra chromosome 13 in each of the bodys cells. Mosaic Patau syndrome is also not inherited. It occurs as a random error during cell division early in fetal development.Patau syndrome due to a translocation can be inherited. An unaffected person can carry a rearrangement of genetic material between chromosome 13 and another chromosome. This rearrangement is called a balanced translocation because there is no extra material from chromosome 13. Although they do not have signs of Patau syndrome, people who carry this type of balanced translocation are at an increased risk of having children with the condition. Recurrence risk
Unless one of the parents is a carrier of a translocation, the chances of a couple having another trisomy 13 affected child is less than 1%, below that of Down syndrome. Diagnosis
Diagnosis is usually based on clinical findings, although fetal chromosome testing will show trisomy 13. While many of the physical findings are similar to Edwards syndrome, there are a few unique traits, such as polydactyly. However, unlike Edwards syndrome and Down syndrome, the quad screen does not provide a reliable means of screening for this disorder. This is due to the variability of the results seen in fetuses with Patau. Treatment
Medical management of children with Trisomy 13 is planned on a case-by-case basis and depends on the individual circumstances of the patient.
Provisional tic disorder approximately replaced transient tic disorder: because initially presenting tics may eventually be diagnosed as chronic tic disorder or Tourettes, transient suggested it could only be defined in retrospect (though that perception did not follow the DSM-IV-TR definition). The term provisional "satisfies experts with a more systematic epidemiological approach to disorders", but should not imply that treatment might not be called for. Differentiation of chronic motor or vocal tic disorder: DSM-5 added a specifier to distinguish between vocal and motor tics that are chronic. This distinction was added because higher rates of comorbid diagnoses are present with vocal tics relative to motor tics. Now includes as Tourettes Disorder patients with tics who experienced a 3-month or longer remission since the first tic, as long as the first tic was at least a year ago. Stimulant use as a cause removed: there is no evidence that the use of stimulants causes tic disorders. New categories, Other specified and Unspecified: for tic disorders that result in significant impairment to the individual yet do not meet the full criteria for other tic disorders. The new categories account for tics with onset in adulthood, or tics triggered by other medical conditions or illicit drug use. References
External links

The Tourette Syndrome Classification Study Group. "Definitions and classification of tic disorders". Arch Neurol. 1993 Oct;50(10):1013-6. PMID 8215958. Retrieved on 2005-03-22
Walkup JT, Ferrão Y, Leckman JF, Stein DJ, Singer H. Tic disorders: some key issues for DSM-V (PDF). Depress Anxiety. 2010 Jun;27(6):600–10. PMID 20533370 doi:10.1002/da.20711