Gene Analysis In A Family With Severe Hypercholesterolemia And Premature Coronary Arterial Disease

Objective:To explore the familial hypercholesterolemia genetic spectrum and investigate thefamily of possible genetic mutations pertaining to cholesterol metabolism, A FH family wasstudied.Methods: A FH family was found through a patient with hypercholesterolemia andpremature coronary artery disease by clinical lipid examination and coronary angiography, andlipid status of all his family members was retrospected. Then the following checks wasperformed:（一）Clinical examination of lipids, ECG, vascular ultrasound, coronaryangiography, etc.（二） Measured lipoprotein a [Lp(a)] by ELISA to exclude Lp(a)synthetic syndrome.（三） Isolated DNA from peripheral blood of the proband and his familymembers.18exons and promotors of LDL-R gene were amplified by PCR with the samecycle parameters and reaction volume，and analysed the segments by SSCP technique. TheLDL-R point mutation was detected by PCR and sequencing. The result of sequencing werecompared with the normal sequences in GenBanK and analysed the nature of its mutations. Bydirectly sequencing, low-density lipoprotein receptor genes in30cases of normal healthy humanas control groupwas were collected, and then it was verified that this mutation site is the cause ofthe FH. At the same time, the known mutations (R350OQ，R353lC，R350lW) of apo B100genethat cause FDB were also detected by PCR and sequencing.Results:By the clinical conventional screening and cardiovascular ultrasound auxiliaryexamination, it was found that the proband，his mother and his son had different degrees ofdyslipidemia and atherosclerosis. A novel missense mutation(T�'C) at the549bp of the LDL-Rexon4, in comparison with30cases of normal healthy human, was confirmed in them bynucleotide sequence analysis, which caused a substitution of amimo acid Phe to Ser at codon549. NO mutation was observed in R3501W、R3531C and R3500Q of ApoB100.Conclusions:1.The proband is diagnosed FH and CAD, and his mother and his sonprobably have FH.2. The T�'C mutation at the549bp of the LDL-R exon4was found in thisfamily, and the mutation makes a substitution of amimo acid Phe to Ser(F202S), suggesting that the muatation causes FH in accordance with autosomal dominant mode of inheritance.3. Theproband with premature coronary heart disease wasn’t caused by Lipoprotein(a) and ApoB100deficiency.