Apolipoprotein E gene polymorphisms in patients with primary osteoporosis

Jun TAO; Yongwu XU; Li DU

ABSTRACT

BACKGROUND:

In recent years, foreign scholars have found that apolipoprotein E gene was associated with osteoporosis and its complicated hip fracture. National scholars adopted polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) to primarily study the correlation of apolipoprotein E gene polymorphism with bone mineral density (BMD) and osteoporosis.

OBJECTIVE:

To observe the polymorphism of apolipoprotein E gene, and analyze its correlation with primary osteoporosis and osteoporotic fracture.

SETTING:

Department of Orthopaedics, Nanchang First Hospital.

DESIGN:

A clinical controlled observation.

PARTICIPANTS:

Sixty patients with primary osteoporosis (31 males and 29 females), were enrolled, including 30 cases of hip fracture, who were newly fractured and diagnosed according to radiogram, and 30 cases of simple osteoporosis; Thirty healthy subjects (16 males and 14 females)were also involved.

METHODS:

Sixty outpatients and inpatients with primary osteoporosis were selected from the Department of Orthopaedics, Nanchang First Hospital from January to December 2002, and they were divided into hip fracture group (n=30) and simple osteoporosis (n=30); Another 30 healthy physical examinees were taken as the healthy control group. All the subjects were fasted for more than 12 hours, and the samples of venous blood were collected on the next morning. DNA was extracted from the separated leucocytes. Gene site DNA amplification was analyzed with polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP). The individual DNA templates (provided by Daan Gene Diagnosis Center of Sun Yat-sen University) of identified apolipoprotein E2/2, E3/3 and E4/4 homozygotes were analyzed with PCR-SSCP, and the band showed that E3 was in the front, E2 in the middle, followed by E4. They were in electrophoresis with DNA templates of the samples at the same time, and the apolipoprotein E genotype of the template could be identified by the migration rate of the band.MAIN OUTCOME

MEASURES:

Apolipoprotein E genotypes were observed.

RESULTS:

All the enrolled subjects were involved in the analysis of results. ① Six genotypes were detected with PCR-SSCP in the 60 patients with primary osteoporosis and 30 healthy controls, including apolipoprotein E2/2, E3/2, 3/3, E4/2, 4/3, 4/4. ② There were very significant differences in the allele frequency of apolipoprotein E4 among the three groups (χ2=17.520, P ＜ 0.01). The allele frequencies of apolipoprotein E4 in the simple osteoporosis group and osteoporotic fracture group were obviously higher that that in the normal control group (χ2=4.904, 16.681, P ＜ 0.01),it was also markedly higher in the osteoporotic fracture group than in the simple osteoporosis group (χ2=4.658, P ＜ 0.01).

CONCLUSION:

Apolipoprotein E4 is closely associated with primary osteoporosis and osteoporotic fracture. Apolipoprotein E is a useful marker for primary osteoporosis, especially for osteoporotic fracture.