Protein C Deficiency
by Drew Roby
Purine nucleoside phosphorylas deficiency, adenosine deaminase deficiency,
and protein C deficiency are genetic disorders that lead to the disabling
of the immune system. These diseases can result in death, sometimes before
the age of 10. Research into these disorders is ongoing, because little
is known about them.
Protein C Deficiency and Purpura Fulminans Purpura fulminans are caused
by the leakage of small blood vessels throughout the body that produce skin
lesions and bruises. This section will focus on purpura fulminans caused
by protein C deficiency and on other problems that occur along with protein
A 13 year old boy was admitted into a hospital. He was suffering from chickenpox
but was suddenly developing a worsening rash. Tests done in the laboratory
revealed that he was suffering from purpura fulminans with a severely acquired
protein C deficiency.
His initial treatment involved intravenous injections of protein C replacement
therapy. That resulted in an increase in the range of 20-50% of protein
C levels of activity. An alternative treatment was then tried in which protein
C concentrate was involved. There was initial concern about the patient's
ability to tolerate increased volume of fluid.
The end result was that the patient responded to the treatment and made
a speedy recovery. The overall conclusion is that protein C concentrate
may be an effective treatment for acquired protein C deficiency.
Protein C Deficiency and Thrombosis Thrombus is an aggregation of platelets,
fibrin, clotting factors, and the cellular elements of the blood attached
to the interior wall of a vein or artery. Protein C deficiency has been
linked as a source of thrombosis. An example of such is the relevance of
heterozygosity for hereditary protein C deficiency as a risk factor for
venous thrombosis has been argued against because heterozygotes without
symptoms have been identified among groups of blood donors and homozygotes
A study was done on one Dutch family over a span of eleven years. All the
individuals were of age 16 and older and were selected randomly. Of the
25 out of 80 probands chosen, 24 showed a point mutation that was identified
in a protein C gene.
Protein C and Mortality Anticoagulant treatment may not reduce the mortality
rate among individuals with inherited protein C deficiency. Protein C deficiency
refers to the inability to prevent blood clotting, often associated with
a higher risk of thrombosis. A group of researchers studied the mortality
rates of several Dutch families over a time span of 173 years. There were
736 relatives with a 50-100% chance of being heterozygous. None of the family
members had mortality rates higher than the general population. There was
no difference in the death rates between men and women or between families.
Protein C Deficiency- Example Case In protein C deficiency patients lack
part of a blood plasma glyco-protein that regulates blood clotting. Small
blood vessels leak throughout the body producing bruises and widespread
skin lesions called purpura fulminans.
An infant, Ian, is admitted the the hospital with red marks on his fingers
and legs that turn large and blue. He is diagnosed with protein C deficiency
because several years earlier, his sister Keri died from it. He is given
protein C pooled from blood donations. He recovers.
To trace the disorder in his family, Ian's parents and siblings are tested
for the level of an antigen indicating the amount of protein C. Since this
is an autosomal recessive condition, it is expected that the parents are
carriers, and, therefore, would have half the normal amount of the antigen
and protein C. An antigen value of 1.00 indicates normal
(wild type). The pedigree and antigen values are:
Mom- .44 carrier
Dad- .46 carrier
Dave- .44 carrier
Sam- .54 carrier
Todd- 1.3 wild type
Ian- < .01
If Ian grows up and has chidren with a woman who is wild type for the protein
C gene, the risk that each child of theirs would be a carrier of this disorder
is 100%. Purpura fulminans can also be caused by leukemia, rubella (German
measles), or ingestion of certain drugs. Purpura fulminans caused by any
of these sources is a mode of inherited protein C deficiency. Obtaining
protein C from donated plasma could introduce infection. A different source
of protein C would be from protein C concentrate via the study of immunogenetics.
British Medical Journal, Oct. 7, 1995 v311 n7010 p910.
The Lancet, Jan. 16, 1993 v341 n8838 p134.
Mosby's Medical, Nursing, and Allied Health Dictionary, 4th Edition.
Pediatrics, Feb. 1993 v91 n2 p418.
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