Months after learning them, a toddler with a fatal disease has forgotten her first words.

A toddler with a rare disease that causes childhood Alzheimer’s has forgotten her first words after learning “hi” and “bye” only months ago.

Marian McGlocklin from California was diagnosed with the heartbreaking condition Niemann-Pick Type C (NPC) disease – also referred to as ‘Childhood Alzheimer’s’ – in March this year. She was just 18 months old.

Her parents Sara, 34, and Paul, 33, received the news after months of testing and doctors appointments and more testing and research. No one could tell them why their youngest daughter wasn’t reaching her milestones. Marian has a four-year-old sister Emily.

“Time stood still when Marian was diagnosed with NPC. Fatal. After the call we were in shock and brokenhearted,” Sara McGlocklin wrote on a GoFundMe page called ‘Hope for Marian’.

“When Marian was born we knew there was something slightly unexpected, her legs was so thin and she felt so delicate. But never did we imagine she was showing early symptoms of a progressive, fatal condition.”

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It’s estimated there are between 1,000 and 2,000 cases of NPC worldwide.

The disease prevents cells from metabolising cholesterol, causing the substance to accumulate in the spleen, liver and brain. Over time, the organs enlarge and dementia sets in. Children lose the ability to move, eat, speak and breathe.

Half of all children diagnosed with NPC will die before their tenth birthday without intervention. With this knowledge, intervention is exactly what Sara and Paul went looking for.

“We began blindly reaching out to other NPC families and quickly learned, this is not a death sentence and there is hope to save Marian’s life. We heard the same thing on every call: get Marian on a highly effective clinical trial drug cyclodextrin as soon as possible. Every day counts.”

Marian McGlocklin. Image via GoFundMe.

Marian is now enrolled in a clinical trial that her parents are hoping will save her life, or allow her to live long enough until a cure is discovered.

Still, the signs of dementia are starting to show. We can only hope the drug trail, the team of doctors, and the family's effort to raise awareness will help little Marian pull through.

"Horrifically, NPC causes dementia – leaving children not being able to recognise their mother’s voice or their father’s smile."

"When she was around nine months old she learnt how to say 'hi' and 'bye' but suddenly one day stopped saying them regularly,” Sara told Yahoo. "Paul and I noticed this happening on a few occasions with new words or actions that she learnt."

"We are so lucky that Marian has been allowed access to the investigative treatment, without it she would likely die which is terrifying.”

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