Kildare mum Aisling McNiffe has warned that the waiting list to see a paediatric rheumatologist has risen from three to four years since Covid-19 arrived.
Ms McNiffe, of Ardclough, Straffan, said her son Jack (15), who has Down syndrome, is waiting for an MRI scan.
"The waiting list in Ireland to see a paediatric rheumatologist is four years. It was three years pre-Covid-19," she said.
"We have only two of these specialists serving the entire country. We should have at least six in a country this size.
"A private appointment is a wait of up to two years.
"This is particularly detrimental to children with Down Syndrome."
Ms McNiffe said Jack has a rare auto-inflammatory disease and chronic arthritis.
"He is under the care of paediatric rheumatology in Crumlin Children's Hospital since he was one year of age.
"He is under 13 medical teams in total as he has complex medical issues, sometimes more depending on what's going on at the time. He needs 24-hour care.
"He is a wheelchair user, he is tube-fed around the clock and he is non-verbal.
"He has a severe intellectual disability.
"He has a heart condition which requires further surgery, he has chronic lung disease which means he has frequent chest infections. Despite all, he is a happy chap."
Ms McNiffe said they were waiting for an MRI scan to see how the latest biologic drug for Jack was working.
"That was due in November just gone. Hopefully, he will have it in early 2021," she said.
Children's Hospital Ireland, in a recent response to James Lawless TD, said there was an active recruitment campaign for an additional rheumatology consultant.