It is estimated that more than 200,000 new cases of invasive breast cancer will be diagnosed in European women in 2007, and over 2,000 new male cases. An estimated 5 to 10 percent of all breast cancers are hereditary. Particular mutations in genes associated with breast cancer are more common among certain geographic or ethnic groups, such as people of Ashkenazi (central or eastern European) Jewish heritage and people of Norwegian, Icelandic, or Dutch ancestry.

The most common sensory disorders in human beings include hearing loss and blindness. Hearing loss is a frequent disorder affecting one in 1,000 children and the prevalence increases with age. Recent data clearly indicated that an overall number of people suffering from hearing loss of more than 25 dB will exceed 700 million by 2015, of these some 90 million will be Europeans. In the majority of the cases, hearing loss manifests before (prelingual), and rarely after (postlingual) development of speech. At least 60% of cases are due to genetic causes (inherited hearing loss or IHL); and may manifest itself as syndromic (20% of all cases) or non-syndromic (80% of all cases) form. Prelingual nonsyndromic hearing loss follows an autosomal recessive trait (75-80%, NSRHL), an autosomal dominant trait (10-20%, NSDHL), a X-chromosomal, recessive trait (1-5%), or is maternally inherited (0-20%). Postlingual nonsyndromic hearing loss usually follows an autosomal dominant trait.

Neurodegenerative diseases are among the most heterogeneous diseases currently known, in terms of symptoms and genes. Molecular laboratories face several problems associated with diagnostic testing: The majority of patients do not have accurate clinical work-up or description of the condition he/she is suffering from. Furthermore, many diseases behave like chameleons meaning that they might manifest with untypical clinical features and present with typical symptoms only in late disease stages (some forms of ataxias such as SCA17 or SCA3, some forms of dystonia, overlap of symptoms between paraplegias and ataxias to name just a few).

A large proportion of mental retardation can be genetically characterized as a monogenic disorder with locus heterogeneity, but the disease genes are unknown for the large majority of cases. Mental retardation occurs in 2–3% of the general population, either in isolation or in combination with other malformations and/or dysmorphisms. Chromosome abnormalities have been recognized for a long time as an important cause of mental retardation.