Biochip for the diagnosis of Familial Hypercholesterolemia
Hypercholesterolemia patients now have a new method of diagnosis that enables them to know for sure if they are suffering from Familial Hypercholesteloremia (FH) or not. The new tool, known as Lipochip, is the first biochip for the diagnosis of Familial Hypercholesteloremia (a pathology that affects some 100,000 persons in Spain).
The majority of those currently suffering from FH are not diagnosed as such. It is calculated that less than 30% of them have received a correct diagnosis with the majority receiving inadequate or inappropriate treatment. Moreover, when the illness is diagnosed, it is often too late as the patient a premature cardiovascular event which may be life-threatening.
Lipochip enables the early diagnosis of a large number of patients in a short space of time. In this way, cardiovascular illnesses can be prevented, these pathologies appearing in more than half of the patients affected by FH before 55 years of age. Amongst those between 20 and 39 years of age who suffer from Familial Hypercholesterolemia, mortality due to a coronary pathology is 100 times greater than amongst those without FH.
The importance of early diagnosis of FH with Lipochip lies in this high incidence of level of premature cardiovascular illnesses amongst FH patients. Without the correct diagnosis and treatment, many patients die between 35 and 65 years of age, and seven out of ten will suffer myocardiac attack before their sixtieth birthday. However, with early diagnosis and treatment, the survival rate and quality of life of patients improves, as these coronary events are greatly diminished. This also reduces hospital costs as there are less cardiovascular events amongst patients being suitably diagnosed and treated.
Another important aspect, that can only be covered by the use of Lipochip, is the detection of the illness amongst young people who do not have symptoms but who, not being diagnosed early or receiving appropriate treatment, are subject to having an unexpected cardiovascular events. Up to now, the clinical diagnosis of FH has been based on typical clinical signs, on analytical data and on family history of the patient.
Thanks to the use of Lipochip, the illness can be diagnosed with complete reliability, i.e. knowing if the patient is a carrier of one of the mutations responsible for FH, using a small blood sample and in a matter of just a few days. Even in those patients that have a definite clinical diagnosis, the detection of the mutation may have prognostic value, given that some studies back up the hypothesis that the type of mutation may also have an influence on the response to pharmaceutical drugs, and so with the type of mutation determining the treatment.
Lipochip enables the carrying out of a genetic diagnosis of Familial Hypercholesterolemia, and considered to be of the greatest reliability. In this way, the appearance of false positives and false negatives are eliminated, which have arisen up to now using the diagnostic table of MedPed (the international programme of the World Health Organisation). The WHO, by means of this programme, recommended the development of techniques capable of detecting mutations in the LDL receptor gene in order to provide a reliable and early diagnosis of Familial Hypercholesterolemia. The mutations in this gene are the cause FH.
The principle of Lipochip is the capacity of DNA to recognise its complementary sequence.
Basically, it consists of a chemically modified glass surface onto which a large number of genic sequences complementary to each of the mutations have been deposited. To this surface the patients sample, marked with a fluorescent molecule, is added. Subsequent illumination with laser enables the identification of which of the points the patients blood sample has bonded to with greatest intensity. In this way specific discrimination between a normal patient and one suffering from Familial Hypercholesterolemia is established.
The novelty of this diagnostic tool is that it enables the analysis of thousands of sequences in a differentiated, rapid and reliable manner, unlike the traditional techniques of the independent analysis of each sequence in question, which can take months.
Lipochip has been designed and developed by the Progrenika-Medplant technological support group, based on knowledge provided by Familial Hypercholesterolemia Foundation and the Department of Biochemistry at the University of Zaragoza.
Garazi Andonegi | Basque research