Hamish was born with biliary atresia, a condition where the bile duct between the liver and the small intestine does not form.
He did not have a gall-bladder.
His mother, Tracey Crossan, said when Hamish was born, she and her husband, Gavin, thought their son's slightly yellow colour was because he had an olive complexion.
It soon became apparent that was not the case and, when he was 3 months old, they were told the worst: without a new liver, he would die within weeks.
Two and a-half months later, Hamish and Mrs Crossan made history.
Thanks to their operations on July 24, 2007, at the New Zealand Liver Transplant Unit at Auckland Hospital, Hamish became the youngest New Zealander to receive a new liver and Mrs Crossan the first live donor mother.
Hamish is now fit and well, and above average height and weight for his age.
"He is a really sweet, caring and sharing boy.
It's almost as if he knows he has had a second chance at life and is making the most of it," Mrs Crossan said.
Hamish recently started attending Tiny Tots play centre in Ranfurly, something doctors initially told the Crossans would be unlikely, as he would not have built up enough resistance to illnesses by that age.
"It's only in the last couple of years that they've changed their way of thinking about that.
"The biggest thing is Hamish still has suppressed immunity, due to the medication he takes so he doesn't reject the donor liver.
He keeps good health but he is susceptible to anything that's going around.
"Chicken pox can be fatal to someone with suppressed immunity.
Hamish is yet to be exposed.
If he does come into contact, he will have to be hospitalised."
Because of the risk to his health, the Crossans have written an information sheet about possible dangers to Hamish and given it to parents of children at the play centre.
"We're lucky we live in a small, tight community.
People are very supportive.
We often get calls from parents to say there is something going around."
Hamish enjoyed his three mornings per week at play centre, Mrs Crossan said.
"He doesn't stop talking about it. He's a bit of a social butterfly and he loves looking after the little kids. He likes being the big brother."
At home, he is big brother to Ryan, who is 2 years old.
When the Otago Daily Times visited, Hamish could be overheard telling his little brother how much he loved him.
Fortunately, Ryan does not suffer the health problems his brother does.
Mrs Crossan is in weekly contact with Starship children's hospital in Auckland.
On top of that, every six months Starship doctors hold a clinic at Christchurch Hospital, so they can check Hamish first-hand.
"They like to physically see him and run through what's been happening during the past six months.
They talk about what the blood tests have been doing and what changes might need to be made [to his medication].
"We've had tremendous support from Starship. I also can't say anything bad about the Ministry of Health, either. Anything Hamish has needed, it's been done."
Hamish's medication consists of eight tablets, taken morning and night, without any grumbles, Mrs Crossan said.
"It's like he's got an internal clock.
He tells you when he needs his meds."
He is also very stoic when it comes to his blood tests.
"He gets a finger prick, right now it's weekly.
When he sees the tubes, he sits on the table and puts his finger out.
He says which one he wants pricked, which makes it a lot easier."
The past year has probably been the most normal for the Crossan family since Hamish was born, Mrs Crossan said.
"There's been little things but we've dealt with them. The blood results have been up and down but they've been generally pretty good.
"We're hoping 2011 will be even less testing. The clearer his blood results are, the less he has to be tested. It can be spun out for months. But if he gets sick, they have to be done every couple of days.
"For a long time, I had nightmares we were going to lose him. I've got over that but it's only stopped this year."
