The total number of babies born with Down syndrome in the United States each year is 6,000 - or almost 1 in every 691 births. According to the NICHD (2014a), there are more than 400,000 people living in the United States with Down syndrome. In Australia the rate is much lower, with an estimated 270 babies being born with Down syndrome in 2009. This equates to a frequency of approximately 1 in every 1101 births in Australia, the majority being in New South Wales [Dow13]. The older the mother of a baby is, the more likely the baby has of being diagnosed with Down syndrome. A mother at age 25 has chance of 1 in 1300 whilst if a mother was 49, her chance is 1 in 25 [Nat141]. The most noticeable physical symptoms of people diagnosed with Down syndrome include: - Reduced muscle tone - Small head, ears and mouth - White spots located on the iris of the eye (Brushfield spots) - Large spacing between first and second toes - Short neck - Slanted upwards eyes - Stubby hands and short fingers - A single crease across the palm of the hand - A flattened facial profile and nose People with Down syndrome may also have intellectual symptoms such as: - A short attention span - Bad judgement - Thoughtless behaviors - Late speech and language growth - Slow learning [NIC14] Human cells are usually made up of 46 chromosomes, 23 from your father and 23 from your mother, which have been paired. In Down syndrome, an irregularity in the cell division involving chromosome 21 arises. There are three forms of Down syndrome. Trisomy 21 The primary type of Down syndrome being the main cause 95% of the time. Trisomy 21 is caused by an error which gives all cells an extra copy of chromosome 21, instead of the usual two. It is initiated by atypical cell division during growth of the egg or sperm cell (Mayo Clinic Staff, 2014a). Mosaic Down Syndrome The rarest form of Down syndrome, accounting for only 1% of cases. It is similar to Trisomy 21, except for the fact that the extra chromosome 21 does not appear in all cells. The ordinary and unordinary cells form a kind of mosaic (