Kampala — SIMON is a happy father of three health children. But his nine-month old baby, the fourth addition to the family, has changed this pattern. He was diagnosed with sickle cells recently.

None of Peter's close relatives has suffered from this disease.

But as he tried to find answers to this strange occurrence in his family, he discovered that his great grandfather had a similar condition.

Medical experts say it is important to know your family medical history. Tracing your family tree and finding out vital information about the lives of previously unknown relatives can reveal vital information about health issues in your family lineage.

Dr Misaki Wayengera, a molecular pathologist and lecturer at the College of Health Sciences, Makerere University, notes that we inherit diseases from our parents.

However, some of the diseases may take long to manifest in a family lineage.

Wayengera observes that the reason for this is because nature allows for shuffling of genes during the process of creating gametes (sperm and ova).

This ensures that the new-born child, though sharing some traits of the father or mother, is a unique individual and may not inherit the disease of the parents.

This explains the diversity in some of the human characteristics like intelligence, size of nose or colour of hair or eyes or skin, which we see in children from the same family.

Dr Emmanuel Tenywa, of the World Health Organisation (WHO), says today people are more aware about inherited diseases unlike in the past when they were blamed on superficial causes like witchcraft and bad spells.

He adds that genetic diseases are caused by abnormalities in genes and can also be affected by the environment.

One may have a genetic predisposition that they possibly inherited a gene that can cause a particular disease. The risk can also be made worse by environmental factors.

"There are more genetic diseases because of increased population growth and environmental hazards which could make them more prominent," Tenywa says.

Wayengera advises that if someone knows that they are carriers or have a disease gene, they should inform their partner and encourage him/her to go for screening too.

"You can avoid a marriage where both of you are carriers, because chances of your children becoming sick are high. And children who get such diseases go through life in pain," Wayengera notes.

Common conditions include thyroid problems, cancer, Parkinson's disease, sickle cell, brain tumors, migraines, glaucoma, osteoporosis, heart attack and type 2 diabetes.

Type 2 diabetes affects nearly 21 million people in the US and more than 200 million people worldwide.

According to the Center for Inherited Disease Research (CIDR) at Johns Hopkins University, the incidence of inherited diseases has skyrocketed in the US and many other developed nations over the last 30 years.

Medical reports show that sickle cell anaemia and albinism (an abnormality of skin and hair colouring due to under production of melanin) are common inherited diseases in Uganda.

Inheritance of both sickle cell anaemia and albinism are recessive, which means that the trait can only manifest in people with a double portion of the gene, while those with just one portion or carriers, have the gene but not the disorder or disease.

The risk depends on the mode of inheritance. It also depends on whether one is affected or not and the severity of the disease.

For instance, with the above two recessive disease and disorder, the mode of inheritance is recessive.

This means that there is only a quarter (25%) chance that if a person with no sickle cell anaemia but a carrier married a girl or man who is also carrier will give birth to a child with the disease.

However, it does not mean that if you give birth to four children, only one will have the disease.

Wayengera explains that some couples may be unlucky that the chance catches them at every conception, meaning that all their offspring will be sick, while others are blessed that the chance never catches any of their children.

On the other hand, this chance is absent if one of the parents is normal, although the gene will be propagated among the children in a carrier form.

"Should one of the parents be a sickler and the other a carrier, the chance of having children who are sicklers is increased to fifty; with all others being carriers.

These probabilities are complex and may be left to the doctor to explain," says Wayengera.

Dealing with them

According to medical experts, persons intending to get married require counselling to prevent such occurrences.

This may not stop two people who may both be carriers, or one carrier and another a sickler (or even normal and sickler) from having a family. However, it is only medically right that such risk is appropriately communicated.