Genetic diseases
Haemophilia
Causes
There is an carrier which is most often the female and there is an uninfected male. When they have children if they girls they will not get the disorder but one of the girls will not have the disorder them self but be a carrier for her children. If they had for example 4 boys, 3 of them would be infected with the disorder but one child will not be.
Symptoms
General symptoms of haemophilia are internal or external bleedings. This are called bleeds also a person suffering from haemophilia usually has big bruises and bumps tend to be giant.
Cure/Treatment
There is no cure for haemophilia but it can be managed with regular infusions of the clotting factor. Colour blindness
Causes
Colour blindness is mostly an inherited disorder. Two of the most common inherited forms of colour blindness are protanopia and deuteranopia. One of the common colour vision defects is the red-green deficiency which is present in about 8 percent of males and 0.5 percent of females of Northern European ancestry.
Symptoms
As the name states colour blindness is when a person cannot see a colour or a collection of colours.
Cure/treatment
There is no treatment to cure colour blindness but an optometrist can give you coloured spectacle lenses. Also there have been many applications on smart phones that are meant to help people with colour blindness

Down syndrome
Causes
Down syndrome is caused by having three copies of the genes on chromosome 21, rather than the usual two. The parents of the affected individual are typically genetically normal. Those who have one child with Down syndrome have about a 1% risk of having a second child with the syndrome, if both parents are found to have normal karyotypes.
Symptoms
People with down syndrome most often have physical and mental disabilities. As adults, their mental abilities are typically similar to those of an 8 or 9 year-old.
Cure or Treatment
Efforts such as early childhood intervention, screening for common problems, medical treatment where indicated, a good family environment, and work-related training can improve the development of children with Down syndrome. Education and proper care can improve quality of life. Raising a child with Down syndrome is more work for parents than raising an unaffected child. Typical childhood vaccinations are recommended.