Matthew is one of 26 children chosen to go on a two-week "California adventure" with Koru Care in October.
The 13-year-old has a form of occipital horn syndrome which affects his ability to absorb copper properly, and gives him problems with adrenaline. This means many visits to doctors and the hospital.
One of Matthew's older brothers, Peter (20), also has the genetic condition, and is quite sick.
Matthew said he was looking forward to seeing his brother Peter in Auckland before flying to California on October 20.
"Going to California will be great: Disneyland, amusement parks, and shopping."
The South Otago High School pupil said he was particularly looking forward to visiting Knott's Berry Farm, a huge amusement park with about 40 different rides and nine rollercoasters.
It has been a tough time for Matthew and his family. His father John died almost two years ago, and since then Matthew's condition has become more serious.
Matthew's mum Sharon said the trip was a "once in a lifetime opportunity" for her son.
"I'm a wee bit worried, but it's a great opportunity."
Special needs teacher Hannah Alabaster said the trip would give Matthew confidence to tell others about his condition as well as giving him a well-deserved break.
"Matthew's a very bright student. I really think it would be a life-changing experience for him."
However, the trip costs about $6200 per child, so Matthew and his supporters have been working hard to raise money and hope to raise a bit extra to pay for his passport and give him some spending money.
South Otago High School has raised about $750 so far through a mufti day and an international themed day.
Anyone wanting to give money towards Matthew's trip can do so at the school office, or at Holmdene Rest Home which is also running a raffle.
Matthew said he planned to hold a sausage sizzle and was thinking of other fundraising ideas.
