Objective: To inventory the possibilities of tracing relatives of patients with familial hypercholesterolaemia (FH) by means of family tree research and DNA diagnostics.
Design: Descriptive.
Method: Blood from patients with the clinical diagnosis of 'FH' was sent, through one of the lipid outpatient clinics in the country, to the Foundation for Tracing Hereditary Hypercholesterolaemia (StOEH) for DNA examination, to characterize the genetic defect. If a mutation was diagnosed in this index patient, he was invited by telephone by a StOEH staff member to have DNA testing done in relatives (especially those of the first degree). The data were stored in a data base. The analysis concerns the patients approached in 1994-1997, as well as those in whom the serum concentration of LDL cholesterol was also determined in 1993-1995.
Results: A total of 3013 persons were approached and examined: 146 index patients and 2867 relatives. The DNA diagnosis of 'FH' was made in 1067 relatives (37.2%), 585 (54.8%) women and 482 (45.2%) men. Of these, 21.2% were younger than 20 years, 37.0% 20-39 years, 26.6% 40-59 years and 15.2% > or = 60 years; 44.1% reported being known with a raised cholesterol level, 29.4% were treated with cholesterol-reducing drugs and 6.1% were suffering from a cardiovascular disease. Of the 990 persons in whom the serum LDL cholesterol level was determined, 325 (32.8%) were carriers of a mutation in the LDL receptor gene. 21.2% Of them had a LDL cholesterol level < P95. In the non-carrier group, 14.6% had a serum LDL cholesterol level > P95.
Conclusion: Tracing FH patients is feasible in practice and leads to detection of as yet untreated patients.