Ib100 WebEx2

Cyclic Neutropenia is a rare autosomal dominant genetic disorder also known as Cyclic Hematopoiesis. The gene mutation occurs on chromosome 19 at the gene map locus 19p13.3. It is at the beginning of the chromosome, or at least at the edge of the shorter arm of the submetacentric chromosome. The normal protein this region of the chromosome codes for is Elastase 2, Neutrophil, an enzyme. There are six similar Elastase enzymes. Elastase 2 is found within neutrophil cells' lysomomes (the tiny sacs that store digestive enzymes within cells). This enzyme splits other proteins (from invading bacteria) apart with the use of water.

The mutant enzyme causes an, on average, 21 day cycle where 3 to 6 of those days the persons neutrophil cells/levels plummet. During that time they are susceptible to "opportunistic infection" because they basically have little to no white blood cells to fight infection. Mouth ulcers, fever, malaise, and flu-like symptoms are common, with blood poisoning and more serious life-threatening infections possible (The Nicola's family history,another history ). There is currently only a hypothesis as to why this mutation causes a cycle, involving a bad interaction between this enzyme and another.

Background
A couple wants to have babies. The male has had Cyclic Neutropenia since birth, and his parents and brothers do not have the disorder. The female does not have the disorder either.

Question: What are the chances their children will have the genetic disorder?

Answer
Since his parents do not have the disorder, it arose from random genetic mutation. It is extremely unlikely that he is homozygous dominant (EE) for the genetic disorder, because random mutations are rare, and the same mutation happening twice is even more rare. So, without a genetic test comparing both of his chromosome 19's, we will assume he is heterozygous for Cyclic Neutropenia (Ee).

	The Woman's Eggs
The Man's Sperm	e	e
E	E e	E e
e	e e	e e

The Punnett's Square above shows their children have a 50% chance of having a heterozygous case of Cyclic Neutropenia.