Porphyria

1.  Introduction

In May 2006, the New Scientist announced a forthcoming paper, to be published in the Journal - Toxicology and Applied Pharmacology, Volume 214, Issue 2 , 15 July 2006, Pages 99-108. A version is available on the internet. The study proports to show that urine samples from children with autism contained abnormally high levels of a family of proteins called porphyrins. The lead author, Richard Lathe is quoted as saying "It's highly likely that heavy metals are responsible for childhood autistic disorder in a majority of cases."

2.  Porphyria

Porphyria is not a single disease but a group of at least eight disorders that differ considerably from each other. A common feature in all porphyrias is the accumulation in the body of "porphyrins" or "porphyrin precursors." The signs and symptoms of porphyria vary among types. Some types of porphyria (called cutaneous porphyrias) cause the skin to become overly sensitive to sunlight. Areas that are exposed to the sun develop redness, blistering, and often scarring. The clinical features of other types of porphyria (called acute porphyrias) affect the nervous system. Appearing quickly and lasting from days to weeks, these signs and symptoms include chest and abdominal pain, emotional and mental disorders, seizures, and muscle weakness. Some porphyrias have a combination of acute symptoms and symptoms that affect the skin.

2.1  Porphyria and Autism

It is clear that the symptoms of porphyria do not correspond to the characteristics of autism. There is no indication of skin sensitivity in autism. Moreover, the symptoms of porphyria are described appearing quickly and lasting for days or weeks, while the neurological symptoms of autism are life-long.

2.2  Porphyria and Heavy metal poisoning

The forthcoming paper claims a well established correlation between porphyrins in the urine, and heavy metal toxcicity. However, this claim rests on a small number of papers, primarily from the group of J.S. Woods. Porphyria can also result from other types of toxic exposure, such as to PCBs, benzene, trichlorethylene and hexachlorobenzene. Thus it is clear that there is no definitive link between pophyrin detection in the urine and heavy metal toxcicity.