Saturday, June 13, 2015

Neonatal Adrenoleukodystrophy

I decided to post about a very rare genetic disorder known as neonatal adrenoleukodystrophy. Most people have never heard of this rare disorder. This is genetic disease that I am very familiar with because my cousin was diagnosed with neonatal adrenoleukodystrophy at the age of 6 months and sadly died at the age of three. By all appearances Andy was a normal newborn but it wasn’t long before my aunt and uncle noticed that something was wrong. Initially the pediatricians told my aunt and uncle that everything was fine and not to worry. Andy did not respond to visual cues or sound. Very soon after birth it was determined that Andy was deaf and blind. He was missing all of the milestones children should hit by the age of 6 months. Andy could barely hold his head up and could not sit up or role over on his own. It was a mystery to my family until he went to a specialist and it was determined that he had a very rare condition called neonatal adrenoleukodystrophy. This genetic disorder affects about 1 in every 50,000 births. This disorder is characterized by the breakdown or loss of the myelin sheath surrounding the nerve cells in the brain which causes dysfunction of the adrenal glands. In class we learned that the myelin sheath is responsible for the transmission of the electrical impulses along the axon. The breakdown of the myelin sheath affects one’s ability to transmit information and this explains why my cousin was unable to see, hear, roll over or even sit up.  Unfortunately, this particular form of leukodystrophy is fatal and there is currently no cure. For this reason my family has been very involved with promoting awareness and supporting fund raisers. Because this disorder affects the nerves and adrenal glands this is a disease that will get progressively worse. This specific form of leukodystrophy is caused by a mutation in the PEX5 gene. For an individual to have this disorder they must have two copies of the mutated PEX5 gene. Both my aunt and uncle were carriers of this mutated PEX5 gene. My aunt and Uncle gave birth to another son several years later and were very lucky not to have passed along this disorder to their second son. Because they were both carries of the recessive mutated gene PEX5 they have a 50 % chance of having a child with the disorder. I found the topic of this blog post interesting not only because of my personal connection but also because of how this disorder relates to multiple topics leaned about and discussed throughout this class. During this class we discussed at length the transmission of recessive alleles and the pedigree analysis and genetic counseling used.  We also discussed the function of the myelin sheath on the neurons axon and what this is responsible for. Currently there is research being conducted using stem cell transplantation using umbilical cord cells and bone marrow cell. Unfortunately these treatments can only slow this degenerative process of the myelin sheath deterioration. The most effective way to prevent this disorder is understanding genetic testing for the recessive alleles.

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