Abnormalities

Cri-du-Chat Syndrome=

Founder-The geneticist Jerome Lejeune identified cri-du-chat syndrome in 1963

caused by a break in the DNA molecule that makes up a chromosome. In most cases, the chromosome break occurs while the sperm or egg cell (the male or female gamete) is developing. When this gamete is fertilized, the child will develop cri-du-chat syndrome. The parent, however, does not have the break in any other cells of the body and does not have the syndrome. In fact, breaks are so rare that it is very unlikely to happen again if the parent has another child.

It is possible for a child to inherit a broken chromosome from a parent who also has the disorder.

Characteristics of the Syndrome

•Major identifying characteristics

•Monotone, weak, cat-like cry

•Small head (microcephally)

•High palate

•Round face

•Small receding chin (micrognathia)

•Widely spaced eyes (hypertelorism)

•Low set ears

•Low broad nasal ridge

•Folds of skin over the upper eyelid (epicanthic folds)

•Distinctive palmar creases (creases on the palms of the hands)

•feeding problems because of difficulty swallowing and sucking,

•low birth weight and poor growt

Incidence rate- Cri-du-chat syndrome is listed as a "rare disease" by the Office of Rare Diseases (ORD) of the National Institutes of Health (NIH). This means that Cri-du-chat syndrome, or a subtype of Cri-du-chat syndrome, affects less than 200,000 people in the US population

Down Syndrome- In 1959, the French physician Jérôme Lejeuneidentified Down syndrome as a chromosomal condition.

Cause-Down syndrome is typically caused by what is called nondisjunction. Nondisjunction happens when a pair of chromosomes fails to separate during egg (or sperm) formation. When that egg unites with a normal sperm to form an embryo, the embryo ends up with three copies of chromosome 21 instead of the normal two. The extra chromosome is then copied in every cell as the baby develops.

Interestingly, nondisjunction events seem to occur more...