Baby Charlie Gard's medical condition: What you need to know

— -- The ongoing story of Charlie Gard –- a baby born in London with a rare genetic disorder known as Mitochondrial Depletion Syndrome -– has gained international attention, with such prominent figures as Pope Francis and President Donald Trump commenting on his family’s ordeal.

Charlie, born on August 4, 2016, has been on life support for several months at the Great Ormond Street Hospital in London. As his condition continues to deteriorate, his parents are battling with the European courts over how to move forward with his care.

Last week, New York Presbyterian/Columbia Medical University Hospital offered to administer experimental treatment therapy to Gard as long as the British government approves a safe medical transfer to the United States. Thus far, the courts have denied the transfer, but Charlie’s parents have continued their battle with the legal system.

Meanwhile, Charlie’s incredibly rare form of mitochondrial disease has generated global attention. Here are some of the common questions about Mitochondrial Depletion syndrome.

What is Mitochondrial Depletion Syndrome (MDS)?

MDS is one of a suite of rare disorders that affect the mitochondria –- often described as the tiny powerhouses of the cell. Certain genes ensure that these mitochondria are healthy and produce the energy the cells need. Genes come in pairs, one copy comes from the mother and one from the father. When a baby has MDS, it means that both copies received from the parents for this particular gene –- the one that keeps mitochondria healthy –- are defective. The result is progressive muscle weakness and devastating multi-organ damage.

How Rare Is It?

This disease is very uncommon, with perhaps fewer than 100 cases in the range of related disorders reported worldwide, according to a 2014 study.

What Are the Signs and Symptoms of MDS?

Initially, development may appear normal; however, before these children reach 24 months of age, they usually start exhibiting certain signs of muscle weakness -- for example, weakening of eye muscles leading to droopy eyelids and facial weakness. These children may also exhibit signs of organ failure, such as brain and nervous system problems leading to seizure activity, hearing loss, liver damage and difficulty walking, talking, and swallowing.

What Is the Prognosis for Children with Mitochondrial Depletion Syndrome?

The prognosis, unfortunately, is very poor. Many children with this condition begin having lung muscle weakness early in life. Normally, this progresses rapidly to respiratory failure and death within a few years of onset. The most common cause of death is infection of the lungs.

What Are the Available Treatment Options?

Although supportive therapy is available to help treat the conditions that accompany this syndrome –- such as the seizures and hearing loss –- there is currently no cure for MDS. Experimental therapies tested on mice are intended to target specific defective areas of the mitochondria. Thus far, these treatments have shown only modest success in these animals and some have begun to be tested in a few children. The parents of an American child with a different type of mitochondrial disorder spoke to Gard's parents, according to the Associated Press, about a nucleoside therapy treatment they have been using for their now 6-year-old son who appears to have shown some modest improvement.

Devika Umashanker, M.D., is a recent graduate of the Obesity Medicine fellowship at Weill-Cornell Medical College.