Glucose-6-Phosphate Dehydrogenase Deficiency (G6PD Deficiency)

(Video uploaded 07/2023)


Sub-heading: What is G6PD Deficiency

Nurse: Hello everybody, have you ever heard of an inherited condition called Glucose-6-Phosphate Dehydrogenase Deficiency? It is also known as G6PD Deficiency in short or Favism. When taking certain drugs or foods such as fava beans or in contact with mothballs, people with G6PD Deficiency will develop acute haemolysis that is sudden damage of the red blood cells. In order to find it out early and prevent health problems caused by damaged of the red blood cells, the Clinical Genetics Service performs screening tests for babies born in hospitals under the Hospital Authority by testing the umbilical cord blood. For those babies born in private hospitals, parents can consult their private hospitals, obstetricians or paediatricians for further information.

Scene: Mrs. Au's baby confirmed to have Glucose-6-Phosphate Dehydrogenase Deficiency. Nurse Tong counsel Mrs. Au through the phone.

Nurse Tong: G6PD Deficiency is the most common inherited metabolic disease in Hong Kong. It is also very common in Southern China. People with this disease do not have enough amount of an enzyme called G6PD in their red blood cells. This enzyme helps to keep red blood cells stable. Most affected people do not have any symptoms. When they are exposed to some Chinese or Western medicine, mothballs or have serious infection, their red blood cells may be damaged in a large scale within a very short time. If this happens, large amount of haemoglobin will be broken down into excessive bilirubin (a pigment). This in turns overloads the liver and results in severe jaundice (i.e. yellowing of the skin and the eyes).

Mrs. Au: It sounds serious. What can I do for my baby?

Nurse Tong: Try not to be too frightened. In fact, such a rapid breakdown of red blood cells can be prevented. People with G6PD Deficiency usually enjoy good health if they avoid exposing to certain triggers.

Mrs. Au: So, Nurse Tong, what should I do?

Nurse Tong: Starting from today you have to observe for any jaundice that is yellowing of skin of your baby. Newborn babies usually develop some degree of jaundice on 3 to 5 days after birth. This will gradually go away without affecting the health of the baby. On the other hand, if a baby with G6PD Deficiency is exposed to certain triggers that caused the breakdown of the red blood cells, the jaundice may appear on the first day after birth or at a later time. Moreover, the jaundice may persist or even get worse.

Mrs. Au: What will happen to babies if jaundice persist and get worse?

Nurse Tong: Just as I've mentioned, breaking down of the red blood cells produce a lot of bilirubin. This pigment can enter the brain of the newborn baby causing long term brain damage like hearing loss, limb movement disorder and intellectual impairment etc. However, with early detection and treatment the jaundice can be controlled effectively. So, please do arrange an appointment with the Maternal and Child Health Centre as soon as possible to follow up your baby's jaundice.

Mrs. Au: So apart from jaundice, are there other symptoms I have to take note of?

Nurse Tong: The major symptoms include: yellowing of the white of the eyes and dark coloured urine. Besides, the baby may appear overly tired and sleepy. Older children may look pale and extremely tired. They may also complain of difficulty in breathing and heart beating rapidly. If the above symptoms are observed, you should consult the doctor immediately.

Mrs. Au: Just now you've mentioned that our baby should avoid exposing to certain triggers. So, what are these triggers?

Nurse Tong: It's a very good question. People with G6PD Deficiency should remember to avoid the following things for their whole life: Firstly, avoid the following Chinese herbal medicines such as Rhizoma Coptidis(Huang Lien), Calculus Bovis (Neu Huang), Flos Chimonanthi Praecocis (Leh Mei Hua), Flos Lonicerae (Kam Ngan Fa) and Margaritas. Secondly, Western medicine such as certain antibiotics and Antimalarials, Aspirin group Antipyretics if used in high dose should be avoided as well. To make it simple, all medicines should be prescribed by doctors in order to avoid taking those drugs which can trigger red blood cell damage. Thirdly, for food stuff, don't let your baby eat fava beans. That is broad beans or their products, such as fava pastry. Lastly, for household products, avoid your baby in contact with mothballs or naphthalene-containing products. The above information is listed on the G6PD Deficiency card, also known as green card, and the leaflet on G6PD Deficiency. Please keep this handy green card with you all the time. Finally, remember to show this green card to your doctor and inform him your baby has G6PD Deficiency.

Sub-heading: Frequently Asked Questions

Scene: Mr. Au and Mrs. Au bring their baby to Maternal and Child Health Centre for registration.

Nurse Ho: Good morning Mr. and Mrs. Au. I'm Nurse Ho. I've just checked your baby's jaundice. It's not very high, so you don't need to worry. Today, it's your first visit to our centre. Do you have any questions about taking care of your baby?

Mrs. Au: Nurse Ho, my baby has G6PD Deficiency, can I continue breastfeeding him?

Nurse Ho: In general, you can continue breastfeeding your baby. However, if you need to take those medicines or Chinese herbal medicines stated on the green card, you have to stop breastfeeding temporarily to prevent passing those medicine to the baby via the milk. Meanwhile, it's better that you continue to express breastmilk to maintain milk supply. In that case, you can continue breastfeeding after stopping those medicines.

Mrs. Au: People with G6PD Deficiency should avoid certain Chinese herbal medicines and Western drugs. Can my baby take those Chinese folk medicine like Bo Ying Tan and traditional milk supplement for babies indigestion?

Nurse Ho: Indeed, parents should not give medicine to their babies without any doctor's prescriptions. As the Bo Ying Tan contains Calculus Bovis and Margaritas, we should not give this to babies with G6PD Deficiency. The ingredient of over the counter herbal supplement for babies indigestion varies greatly. It's better to avoid giving this to babies. If there really is a need, you should seek advice from a qualified Chinese medicine practitioner.

Mrs. Au: Besides the food mentioned in the green card, is there any other food that my baby should avoid?

Nurse Ho: Whenever you buy anything, you should check ingredients for any triggers stated on the green card. For example, certain brands of vermicelli and mixed beans may contain fava beans. If you are not sure, check with the manufacturer or doctor directly.

Mr. Au: We have to avoid using mothballs, but how about camphor?

Nurse Ho: According to the latest research findings, natural camphor will not trigger breakdown of red blood cells in people with G6PD Deficiency. However, the purity of camphor containing products in the market varies. Therefore, it is better not to use them.

Mr. Au: Can we also use scented aroma, fabric softener and insecticide?

Nurse Ho: Except those triggers mentioned in the green card, there is no current evidence showing that aroma, fabric softener, food or products containing menthol, chamomile tissue and diapers, insect repellents, mosquito coil and medicated oil etc. can damage the red blood cells in people with G6PD Deficiency. However, you should check the ingredients before using them. Should you have any doubts, you'd better consult the manufacturer or your doctor.

Mr. Au: If a baby with G6PD Deficiency does not have any problems after eating the food which should be avoided, can he eat that food in the future?

Nurse Ho: Even though a baby with G6PD Deficiency has no adverse effect after taking those food that may trigger haemolysis, you shouldn't let your baby eat them again. The degree of damage to the red blood cells depends on other factors like the person's health condition and the amount of triggers exposed to. Therefore, for safety's sake, the baby should avoid taking those foods for their entire life.

Mr. Au: When he goes to school, is there any problem if his classmate's uniform has a mothball odour?

Nurse Ho: It's common that the uniform of classmates carries odour of mothballs. However, the dose of mothballs is much lower and it would not lead to haemolysis. If your child smells the odour of mothball, he'd better get away from it. More important is the affected person and their caregiver should not use mothballs for their clothes.

Sub-heading: Inheritance of G6PD Deficiency

Scene: A nurse is introducing G6PD Deficiency to a group of parents.

Nurse Ho: Good morning parents. I am Nurse Ho. Today, I'll focus on the inheritance pattern of the condition and answer some of your questions. Do you know that G6PD Deficiency is the most common metabolic disease in Hong Kong? Around 4.5% of baby boys and 0.5% of baby girls in Hong Kong have G6PD Deficiency.

Dad A: Nurse Ho, my wife and I do not have G6PD Deficiency, why does our son have it?

Nurse Ho: G6PD Deficiency is an X-linked recessively inherited condition. X-linked means that gene responsible for this condition is on the X chromosome, one of the sex chromosomes. Being recessively inherited, it means that not all generations will have this disease. Boys only have one X chromosome. When this carries the gene, he will get G6PD Deficiency. On the other hand, girls have two X chromosomes. Therefore, if only one of her X chromosome carries the G6PD Deficiency gene and the other X chromosome is normal, she will only be a carrier of the gene but with no disease. If both of her X chromosome carry this gene, she will get G6PD Deficiency. That is why most of the people with G6PD Deficiency are males. In your situation, you do not have the G6PD Deficiency. But, your wife is likely a carrier of the gene.

Dad A: So, if we have a baby in the future, will that baby inherit G6PD Deficiency?

Nurse Ho: If mother is the carrier of G6PD Deficiency and father is unaffected, for each pregnancy, there is a 50% chance that a son will have G6PD Deficiency and 50% chance being unaffected. If the baby is a daughter, then there will be 50% chance that she will be a carrier of the deficient gene and the rest will not be affected.

Mum A: My son has G6PD Deficiency. If he gets married in the future, will his children inherit the same condition?

Nurse Ho: For people with G6PD Deficiency, their children may or may not inherit the condition. It depends on the genes of their partners. If the father is G6PD Deficient and mother is unaffected, then for each pregnancy all sons will not be affected while all daughters will be carriers of the deficient gene. If the father is G6PD Deficient and mother is a carrier of the gene, then for each pregnancy, there is a 50% chance for a son to be G6PD Deficient and 50% chance he will be unaffected. On the other hand, there is a 50% chance for a daughter to be G6PD Deficient and the rest will be a carrier.

Mum B: What about my daughter? She has G6PD Deficiency. Will her baby have the condition?

Nurse Ho: If the mother is G6PD Deficient and father is unaffected, then for every pregnancy, all sons will be G6PD Deficient, all daughters will be carrier. In addition, pregnant ladies should inform their doctor about her family history of G6PD Deficiency for antenatal counselling. Although there are no preventive measures for the condition during pregnancy, early detection and with the right precaution can protect babies from any harm caused by acute haemolysis.

Dad B: In this case, does my baby need regular blood testing and follow up consultation?

Nurse Ho: Provided that people with G6PD Deficiency can ensure lifelong avoidance of the food stuffs and products mentioned in the G6PD green card, it is not necessary to have regular blood taking or follow up consultation.

Dad A: I have one more question. If my child grows up and his immunity becomes stronger, can he recover from this disease?

Nurse Ho: G6PD Deficiency is an inherited disease, it is not the problem of the immune system. Therefore, the baby will not outgrow this with age or when his immunity is stronger. If babies with G6PD Deficiency can avoid exposure to triggers, they can lead a healthy and active life as other children. Therefore, please always take with you the green card and inform medical staff about the G6PD Deficient status of your baby during consultation. Also, let your child know that he has the condition and teach him to take precautions to the food or products mentioned on the green card. Do you have any other questions?

All parents: No, thank you very much.

Nurse: After watching this scenario, you should understand more about G6PD Deficiency. Let's go over the main points

  1. Children should avoid exposing to triggers of haemolysis that is damage to red blood cells.
  2. Should there be any signs and symptoms of acute haemolysis, please consult doctor immediately.
  3. Always bring along with you the G6PD Deficiency card.
  4. Inform medical staff that your baby has G6PD Deficiency during consultation.
  5. Let the child understand G6PD Deficiency at the earliest possible age.
  6. Teach him to avoid food and products which can trigger haemolysis.

Although G6PD Deficiency will not be recovered when the child grows up, if the affected person can pay attention to the above precautions, he can also enjoy good health like other children.