A version of this article appears in print on October 13, 2013, on page A 1 of the New York edition with the headline: The Soaring Cost of a Simple Breath. Get Free Email Alerts on These Topics Asthma Drugs (Pharmaceuticals) Prices (Fares, Fees and Rates) Series Inside Health » Too Hot to Handle Arts » The Harmony of Liberty Opinion » Should Beach Privatization Be Allowed? Room for Debate asks whether shorefront homeowners should have to open their land to all comers.
Family history is a risk factor for asthma, with many different genes being implicated.  If one identical twin is affected, the probability of the other having the disease is approximately 25%.  By the end of 2005, 25 genes had been associated with asthma in six or more separate populations, including GSTM1 , IL10 , CTLA-4 , SPINK5 , LTC4S , IL4R and ADAM33 , among others.  Many of these genes are related to the immune system or modulating inflammation. Even among this list of genes supported by highly replicated studies, results have not been consistent among all populations tested.  In 2006 over 100 genes were associated with asthma in one genetic association study alone;  more continue to be found. 
Nebulisers are machines that turn the liquid form of your short-acting bronchodilator medicines into a fine mist, like an aerosol. You breathe this in with a face mask or a mouthpiece. Nebulisers are no more effective than normal inhalers. However, they are extremely useful in people who are very tired (fatigued) with their breathing, or in people who are very breathless. Nebulisers are used mainly in hospital for severe attacks of asthma when large doses of inhaled medicines are needed. They are used less commonly than in the past, as modern spacer devices are usually just as good as nebulisers for giving large doses of inhaled medicines. You do not need any co-ordination to use a nebuliser - you just breathe in and out, and you will breathe in the medicine.