Ask nine-year-old Dominic Vaz how strong a father's love can be and he tells you about the time his father carried him all night long three years ago.
The family was on holiday in Malaysia when the boy's ankle began to swell. He has haemophilia, a rare condition in which the blood does not clot properly.
When it became too painful for Dominic to lie in bed, his father carried him upright, standing up all the time.
"I was very grateful because when he carries me, he gets a backache," said Dominic, who is giving his father, Mr Gerard Vaz, a card and drawing for Father's Day today to thank him for years of love and care.
There are about 500 haemophiliacs in Singapore, of whom about 200 are members of the Haemophi-lia Society of Singapore. There is no cure and victims bruise easily and suffer bleeding into muscles and joints. They can bleed to death when injured.
It is a genetic disorder that generally affects males. That is why the society wants to start a group for fathers of haemophiliacs to get them more involved in caring for their sons and let them draw support from one another.
Vice-president Gan Kim Loon said: "Given that male sufferers may have to restrict their physical activities, fathers play an important role in guiding and encouraging them to do other non-contact sports like swimming."
Said Mr Tan Chyun Yih, 41, who has a 10-year-old son with haemophilia: "I try not to limit him too much so I accompany and coach him in badminton and soccer to keep a closer eye on him."
Children with haemophilia may also need to be carried more than others, even as they grow up, at home and on regular trips to hospital for check-ups. Fathers can step in for this duty too.
Dominic, for example, sleeps on a mattress on the floor to prevent him from falling and injuring himself. His father gets up at midnight every other day to carry the sleeping boy to a bed so that he is in a better position to receive an injection of blood-clotting proteins.
"I don't see all these as sacrifices, really, and I give him the injection at that time so that it lasts till the next school day and this enables him to participate as fully as possible like other kids," said Mr Vaz, 43, a special education teacher.
Mr Lee Kwong Luan, 44, stopped working as a technician in 2009 to take care of his haemophiliac son.
His son Jue Ming, now seven years old, needed to be carried and pushed in a baby pram to get to hospital for weekly injections then.
"It was a struggle to quit because I had been with the company for so long and society always ties a man's identity or worth to his job," said Mr Lee, who had been working for 15 years before he quit. "But it was something I had to do because I couldn't focus at work if my son was not being taken care of."
The family of four now depends on his wife's salary as a human resource assistant to get by. Fortunately, Jue Ming's treatment costs of about $1,400 a month are fully covered by Medifund.
Now the extra time they spend together, including the one-hour bus ride to and from hospital, has strengthened their bond. Jue Ming has since become very fond of the bus journeys and his favourite pastime is to pretend to be a bus driver.
He would "drive" about the house, using a vegetable strainer as his steering wheel.
"My wish for my dad this Father's Day is for him to be healthy because I think that is so important, and in future, I would like to take care of him too," said Jue Ming.