Mosaic Down Syndrome is a genetic condition in which a person is born with an extra copy of chromosome 21 in some cells, affecting less than 1% of those with Down syndrome.

Medically reviewed by Brigid Dwyer, MD Mosaic Down syndrome is a variant of Down syndrome. Down syndrome is a congenital ...

Zambelli was diagnosed with Mosaic Down Syndrome at the age of 23, while 28 weeks pregnant. This combined image shows Ashley Zambelli, 23, left, and Zambelli with her daughter Lillian, right.

Ashley Zambelli opens up to PEOPLE about discovering that she tested positive for trisomy 21 — also known as Down syndrome — after her three kids also tested positive for the mutation.

A mum who was diagnosed with Down’s syndrome aged 23 says people “don’t believe” she has the condition. Ashley Zambelli was diagnosed with mosaic Down’s syndrome in February 2023 after ...

When Hunter syndrome affects the brain, which is about 75% of the time, symptoms usually show up between 18 months and 4 years of age. They start about 2 years later when the disease is milder.

SOX2 anophthalmia syndrome: This condition is rare, but when it does occur, it can cause a child to be born without eyes and experience seizures, brain development issues, and delayed growth.

Explore REGENXBIO's RGX-121 gene therapy for Hunter syndrome, with an FDA decision due Nov 9, 2025. Click here to read my most recent analysis.

DelveInsight’s, “Hunter Syndrome Pipeline Insight 2025” report provides comprehensive insights about 10+ companies and 10+ pipeline drugs in Hunter Syndrome pipeline landscape.

Hunter syndrome is rare and the trial is small, so there are no pre-defined standards for the safety endpoints to be compared against, Denali said. Related.