One of the most debilitating medical conditions in sub-Saharan Africa isn't fatal. In fact， it's easily curable. The culprit is small， but its impact is big. The chigoe flea， more commonly known as a jigger， typically burrows itself into the feet and hands. It prevents millions of children from attending school， stops farmers from working their land， and makes walking all but unbearable.

Men who smoke are over three times more likely than nonsmokers to lose their Y chromosomes， according to researchers who have previously shown that loss of the Y chromosome is linked to cancer.

The study， published Thursday in the U.S. journal Science， may help explain why smoking is agreater risk factor for males compared to females and， in the broader perspective， also why men in general have a shorter life expectancy.

Only men have the Y chromosome， which is important for sex determination and sperm production.

\"We have previously in 2014 demonstrated an association between loss of the Y chromosome in blood and greater risk for cancer. We now tested if there were any lifestyle or clinical factors that could be linked to loss of the Y chromosome，\" said Lars Forsberg of Uppsala University inSweden， who led the study， in a statement.

\"Out of a large number of factors that were studied， such as age， blood pressure， diabetes， alcohol intake and smoking， we found that loss of the Y chromosome in a fraction of the bloodcells was more common in smokers than in non-smokers，\" said Forsberg.

The risk was dose dependent， meaning that loss of the Y chromosome was more common in heavy smokers compared to moderate smokers. Some men who quit smoking even appeared to regain their Y chromosomes.

\"These results indicate that smoking can cause loss of the Y chromosome and that this process might be reversible，\" Forsberg said.

\"This discovery could be very persuasive for motivating smokers to quit.\"

How loss of the Y chromosome is connected with the development of cancer throughout the body is still not clear， the researchers said. One possibility is that immune cells in blood， that have lost their Y chromosome， have a reduced capacity to fight cancer cells.

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