Typhoon and gene

2000/06/27 Roa Zubia, Guillermo - Elhuyar Zientzia

• Genetika
• Anatomia/Fisiologia

In the islands of Micronesia, around 1775, it was a terrible typhoon called Lengkieki. In the Pingelap atoll there was a great storm that caused the almost total disappearance of its population. Nine out of ten people were killed by the typhoon. For the survivors the situation was not easy. The typhoon also destroyed natural resources and was a great famine. The small population after the storm also fell considerably. There were few individuals who had to reform the atoll population. Its proliferation was progressive and currently there are 3,000 people living on their islands.

XX. At the beginning of the 20th century, the doctor Sir Archibald Garrod suffered numerous patients from the Pingelap atoll. Many of the diseases suffered by these patients were the result of the union of patients of the same blood. Fifty years later, while studying the laws of biological inheritance, it was thought that the transmission of genes in consanguinity is homozygous. Genes from hereditary diseases are transmitted from generation to generation in reproductions that come directly from the same ancestor. Therefore, isolated populations are appropriate to identify the gene associated with a disease.

Some ancestors of Pingelape had a curious genetic mutation that produces acromatopsis. Lack of visibility of acromatopsive colors. Some of its inhabitants saw it in black and white. Between the disaster of Typhoon Lengkeki and the famine survivors there was at least one man with the acromatopsis mutation. As a result of the transmission of genetic characteristics by endogamic pairing, 10% of the current population also suffers acromatopsis.

Grey vision

Acromatopsis involves a loss of visual accuracy, photophobia, nystagmus (ocular vibration) and color separation capability. These symptoms come from the lack of electrical signal from the eye cones. Healthy cones generate electrical response based on color. However, cones with acromatopsis do not.

In 1969 doctors Jacob Brody, Newton Morton and Irene Husselman moved to Pingelap to determine the clinical characteristics of the disease. The estimated frequencies in patients and carriers were around 10% and 30% respectively. The acromatopsis gene was discovered in 1997 in some Iranian Jews. This gene was from the second chromosome. Two years later it was discovered in the Pingelape population on the eighth chromosome. The only base of the gene was modified, which causes a small variation of the protein that encodes it. This small change, well known to those of Pingelap, has a huge influence.