You’ve probably never heard of Criciúma. It’s a city in Brazil known for its lumber, tile, textiles, and coal. It’s also, according to the website ResearchGate, the epicenter of an extremely rare condition called Growth Hormone Insensitivity with Immune Dysfunction (GHIID).
A Brazilian research team discovered a strange coincidence in this city of just under 200,000: a high prevalence of GHIID. A phenomenal 10 cases have been reported since 2003, including two Brazilian brothers from Criciúma. According to NIH Genetic and Rare Disease Information Center, only a few cases of GHIID have been reported worldwide and 250 cases of Laron Syndrome — a similar form of growth hormone insensitivity.
The researchers set about compiling data on more than 1,200 adults whose parents or grandparents were born in Criciúma or in the neighboring cities. Testing revealed seven different families who possessed the genetic mutation for GHIID.
Scientists believe that Criciúma suffers from what is known in population genetics as the “founder effect,” the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population.
Criciúma was founded in 1880 with the arrival of 22 families of Italian immigrants, followed by the arrival of Portuguese, German and Polish immigrants. Researchers believe that Portuguese immigrants or their descendants brought GHIID to the community… where it has remained.
“Health professionals from Criciúma and its neighboring cities, including Tubarão, should be aware of the increased risk of homozygosity for this mutation in the region so that new cases are early diagnosed,” the paper’s authors advise.
Although rare, GHIID is easy to spot. It causes severe short stature and other physical deformities and is accompanied by recurrent infections, autoimmune diseases, and progressive pulmonary fibrosis. There is no treatment available at present.
Because of its rarity, this obscure study (published last month in the journal Genetics and Molecular Biology) may provide some invaluable clues to GHIID, Laron, and other rare metabolic disorders.
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