Difficulties can compound exponentially. A study found that in the city of Hong Kong over half of the homeless people in the city (56%) had some degree of mental illness. Only 13% of the 56% were receiving treatment for their condition leaving a huge portion of homeless untreated for their mental illness.The issue of anti-homeless architecture came to light in 2014, after a photo displayed hostile features (spikes on the floor) in London, and took social media by storm. The photo of an anti-homeless structure was a classic example of hostile architecture, in an attempt to discourage people from attempting to access or use public space in irregular ways. However, although this has only recently came to light, hostile architecture has been around for a long time in many places. : 68  An example of this is a low overpass that was put in place between New York City and Long Island. Robert Moses, an urban planner, designed it this way in an attempt to prevent public buses from being able to pass through it. Healthcare
Health care for homeless people is a major public health challenge. When compared to the general population, people who are homeless experience higher rates of adverse physical and mental health outcomes. Chronic disease severity, respiratory conditions, rates of mental health illnesses and substance use are all often greater in homeless populations than the general population. Homelessness is also associated with a high risk of suicide attempts.
Twenty-nine known mutations in this gene are associated with FHM2 (table 2), many clustering in the large intracellular loop between membrane-spanning segments 4 and 5 (figure 1). Twelve of these mutations have been studied by expression in model cells. All but one have shown either complete loss of function or more complex decreases in ATPase activity or potassium sensitivity. Astrocytes expressing these mutant ion pumps will have much higher resting potentials and are believed to lead to disease through a poorly understood mechanism. FHM3 (SCN1A)
The final known locus FHM3 is the SCN1A gene, which encodes a sodium channel α subunit. The only study so far that has found mutations in this gene discovered the same Q1489K mutation in three of 20 families (15%) with 11 other kindreds (55%) already having mutations in CACNA1A or ATP1A2. This mutation is located in a highly conserved region of an intracellular loop connecting domains three and four. This mutation results in a greatly hastened (two- to four-fold) recovery from inactivation compared to wild-type. As this channel is important for action potential generation in neurons,  the Q1489K mutant is expected to result in hyperexcitable neurons. FHM4 (1q31)
The final locus for FHM maps to the q-arm of chromosome 1. A number of attractive candidate genes occur in this area, though no mutations in them have yet been linked to FHM4.