47, XYY syndrome – Y chromosome
47, XYY syndrome, also known as XYY syndrome or Jacob's syndrome, is a genetic disorder characterized by an additional copy of the Y chromosome in each of the male cells.
The signs associated with this process may include an increased risk of learning difficulties and delayed development of speech abilities and movement skills; hypotonia; motor tics; convulsions; asthma; flat feet; clinodactyly (angular deformity of the fingers); tall; and scoliosis (lateral deviation of the spine). In general, affected men have a higher incidence of psychiatric conditions, such as attention-deficit/hyperactivity-disorder (ADHD), depression, anxiety and autism spectrum disorders.
This process is due to the additional presence of the Y chromosome in each of the male cells. Consequently, each cell has a total of 47 chromosomes instead of the usual 46. However, it is unknown why an additional copy of the Y chromosome is associated with some signs of this syndrome. Some men with 47, XYY syndrome have only one extra Y chromosome in some of their cells, a phenomenon known as 46, XY / 47, XYY mosaicism.
Most cases of 47, XYY syndrome are not hereditary. Chromosomal change usually occurs as a random event during sperm cell formation. An error in cell division, known as non-disjunction, can result in sperm with an additional copy of the Y chromosome. If one of these atypical reproductive cells contributes to a child's genetic makeup, this child will have an extra Y chromosome in each one of his body's cells. On the other hand, mosaicism 46, XY / 47, XYY neither is inherited. It occurs as a random event during cell division at the beginning of embryonic development. As a consequence, some of the cells of an affected person have an X chromosome and a Y chromosome (46, XY) and others have an X chromosome and two Y chromosomes (47, XYY).
Tests performed in IVAMI: in IVAMI we perform the detection of mutations associated with 47,XYY syndrome, by a quantitative Real time PCR procedure.
Recommended samples: non-coagulated blood obtained with EDTA for separation of blood leucocytes, or a card with a dried blood sample (IVAMI can mail the card to deposit the blood sample).