What is a chromosome? Chromosomes are bundles of tightly coiled DNA located within the nucleus of almost every cell in our body. Humans have 23 pairs of chromosomes. Illustration showing how DNA is packaged into a chromosome. Disability Fact Sheet #4 (FS4) Incidence of Down Syndrome Nearly 5,000 babies are born with Down syndrome in the United States each year.2 This means that 1 in every 733 babies is born with this condition.3 Although parents of any age may have a child with Down syndrome, 80% are born to women under the age of 35.4 NICHCY Disability Fact Sheet ...

Nov 28, 2016 · Jacobsen syndrome is a rare congenital condition that’s caused by the deletion of several genes in chromosome 11. It’s sometimes called partial monosomy 11q. It occurs in about 1 in 100,000 ... sex chromosomes - the X and Y chromosomes that determine a person's gender; women normally have two X chromosomes and men normally have one X and one Y. syndrome - a collection of traits, health problems, and /or birth defects in an individual which usually has an underlying cause Infants with hypoplastic left heart syndrome may have lifelong complications. They will need regular follow-up visits with a cardiologist (a heart doctor) to monitor their progress. If the hypoplastic left heart syndrome defect is very complex, or the heart becomes weak after the surgeries, a heart transplant may be needed.