.

    6
     
 

Urine samples:

1. Normal urine,aged


2. Urine from AIP patient during crisis, aged


3. Port wine, aged


4. Normal urine plus porphobilogen, aged

  
 
 
     
  Inheritance.  
  Barker and Estes13 were the first to note that AIP runs in families. The extensive studies of Waldenström in Sweden firmly established the inherited nature of the disease.  
     
  * The disease follows an autosomal dominant pattern of inheritance; if one parent is a carrier then on the average 50% of the children will bear the defective gene.6 However, the penetrance is variable, so that in some families only a fraction of the carriers actually express signs and symptoms of the disease.14  
     
  7 
     
  * The gene for porphobilogen deaminase is carried on chromosome 11, and maps at11q23.3. Much information on mutations within this gene and mapping is given at the Online Medelian Inheritance in Man website:15
http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=176000		  
     
  * Firm identification of AIP is usually supported by finding about 50% of normal enzymatic activity for porphobilogen deaminase in circulating red blood cells. However, since 1987, it has been established that some AIP cases have normal amounts of the enzyme in bone marrow and red cells but 50% of normal in the liver cells.16 These are so-called non-erythroid variants,15 which otherwise do not differ from classic AIP in their biologic course.  
 
  3  
     
  Prevalence.  
  Acute intermittent porphyria is considered to be a rare disease in that a prevalence of 1 in 50,000 has been estimated world-wide. A recent suggestion for Sweden is of the order of 1 in 10,000, and in the north (where Waldenström did his classic wiork) it may be 1 in 1,000. As long as these rates are based on the display of AIP symptoms, they surely underestimate the total number of persons (i.e. including those with latent AIP).  
     
  The family of Vincent van Gogh.  
  * His mother died at 88, having led a seemingly healthy life.  
     
  * Vincent's father, the Reverend Theodorus van Gogh, died at 63. His studies for the church had been interrupted by serious illness. He was judged not to have been in very good health most of his life.17 It is believed that he died from a stroke and, because hypertension is present in 40% (ref. 5) or over 50% (ref.18) of AIP patients, this underlying disease would be one of many possibilities compatible with that cause of death. Of Vincent's parents the father may be the more likely (obligate) carrier of AIP, but this is little more than an educated guess. He led a careful and balanced life in his "post in the wilderness" and may have avoided the precipitating factors that affected three of his six children.  
     
     
  * The cases for Vincent's brother Theo (1857-1891) and his sister Wil. (1862-1941) have been presented1,2 Arnold1 selected cases of AIP from the 20th century that had analogies to the illnesses of Vincent, Theo, and their sister Wil. It behooves proponents of other hypotheses to provide similar case histories, complemented with the diagnostic insights of modern medicine, to either support or damage their alternatives.  
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