Osteoporosis

Observed genes

Polygenic score

Influential genes: CPED1,FMN2,ERC2,WNT16,LINC02341

The WNT16 gene has been identified to be associated with bone mineral density and fracture risk

Certain variations in the COL1A1 gene have been linked to lower bone density and higher risk of osteoporotic fractures.

The ESR1 gene codes for estrogen receptors, which play a key role in maintaining bone density.

Overview

Osteoporosis is a systemic skeletal disease characterized by low bone density and microarchitectural deterioration of bone tissue with a consequent increase in bone fragility and susceptibility to fractures. According to WHO criteria, osteoporosis is defined as bone mineral density (BMD) that lies 2.5 standard deviations or more below the average value for young healthy adults.

Prevalence & Risk factors

Currently, over 200 million people worldwide suffer from osteoporosis^[2]. Postmenopausal women and the elderly are the most susceptible groups, as an abrupt decrease in estrogen and age-related processes play a key role in the development of this disease. 

These two groups compose the most common form of osteoporosis: 

- Primary osteoporosis: we differentiate postmenopausal-Type I in which estrogen levels are decreased promoting bone resorption, from senile-Type II where the loss of bone mass is gradual as patients age, especially over 70 years old. 

- Secondary osteoporosis: occurs as a consequence of other primary disorders or most commonly due to long-term therapy with corticosteroids. 

Any of the causes of osteoporosis might be worsened by low body weight, malnutrition or smoking, all of those playing a role in the metabolism of bones.

Genetics

Osteoporosis is a polygenic disorder, meaning several genes take action in the progression and fracture risk of this condition. The genetic factors play an important role in regulating bone mineral density and other determinants of osteoporotic fracture risk, such as ultrasound properties of bone, skeletal geometry and bone turnover.

Signs & Symptoms

Although the affected people are mostly asymptomatic, pathological fractures are usually the first sign. These fractures are caused by everyday-activities or minor trauma that shouldn’t normally cause a bone to break.. Their most common location is vertebral, followed by the femoral neck, distal radius and other long bones. Symptoms will vary according to the location of the fracture/fractures, commonly causing severe pain, loss of weight and/or structural malformations (e.g. spine kyphosis) over time.

Diagnosis

In order to diagnose correctly and predict the probability of fractures, the patient must undergo bone mineral density (BMD) tests which include a special type of X-rays called dual-energy X-ray absorptiometry (DEXA scan). This scan is considered in all women over the age of 65 and men over 70 as a screening test. The results will be expressed as a so-called “T-score” - the difference in standard deviations between one’s BMD and a reference mean, which we can then apply to the WHO criteria above-mentioned.

Therapy

Therapy is based on treating and preventing fractures, thus medical treatment is most often required with the drug of choice being bisphosphonates. This medication will decrease the resorption of bone and strengthen it. Lifestyle prevention of osteoporosis is recommended with sufficient daily intake of calcium and vitamin D as well as physical activity and smoking/alcohol cessation.

Prevention

It is important to notice that osteoporosis is preventable. The methods to prevent it are mainly based on lifestyle modifications and weight bearing activities such as walking, dancing or low-impact aerobics. Once the disease has developed the prevention of all kinds of trauma and falls is essential. Postmenopausal women are recommended to take calcium and vitamin D supplements in order to strengthen the bones and decrease the risk of fractures.

Prognosis

There is no cure for this condition but the prognosis is favorable when all the preventive measures are followed. When detected in early stages, complying patients can increase bone mineral density (BMD) and decrease fracture risk following these lifestyle modifications and live a normal active life.

Recommendations

• If you experience easy fracturing after trauma or falls, you should get an appointment with an orthopedist.
• Improve your health by exercising at least 20 min a day and by avoiding alcohol and smoking.