In the movie, Lorenzo Odone is initially portrayed as a normal, happy, healthy child whose health suddenly declines. Taking place from 1984 to 1987, the parents (Augusto Odone, played by Nick Nolte, and Michaela Odone, played by Susan Sarandon) become involved in a fight to save the life of their son. The Odones train themselves in biology to develop a treatment for their son. The sympathetic portrayal rarely fails to become an indelible memory for my students.

In 1996, Phil Collins has recorded a song called "Lorenzo" in his "Dance Into the Light" album. The lyrics were written by Michaela and Lorenzo.

The disease portrayed in the movie is called adrenoleukodystrophy (ALD). Very simply, this disease is due to the removal of white, lipid sheaths (myelin) that surround long thin cells called neurons.  Neurons, of course, allow us to think and to move (e..g, control our muscles).

"Leuko" is white (referring to the myelin that covers neurons and makes neurons look white) whereas "dystrophy" refers to "abnormal development." Although there are many forms, the symptoms of the form of ALD shown in the movie begin at age 5 to 12 and death occurs within a couple of years (Moser, 1997). The symptoms (dementia, loss of sight, hearing, speech, and ability to walk-ambulation) are believed to be due to solubilization and removal of the myelin sheath around neurons by a build up of very long chain, saturated fatty acids (VLCSFAs) in the body. Without a myelin sheath, nerve cells do not conduct action potentials; in essence, the neurons stop telling muscles to contract and the patient cannot move. Multiple sclerosis, using a different mechanism, will also remove myelin.

The "very long chain" part of the VLCSFA refers to fatty acids that are 24 or 26 carbons long ("short" fatty acids have 14, 16, or 18 carbons)(Fig. 1A, B). The "saturation" of VLCSFAs refers to the fact that the carbons in the chain are saturated with hydrogens (all carbons, except the carboxyl carbon at the right end of the fatty acids in Fig. 1A and B, have at least two hydrogen atoms attached). In contrast, unsaturated carbon chains have one or more double bonds (since the carbons in the double bond have only one hydrogen attached, the carbons are not saturated with hydrogen).

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Triglycerides are made up of three fatty acids attached to a glycerol backbone (Fig. 1C). If one of the 3 fatty acids is an unsaturated cis fatty acid with a kink, then the triglycerides do not pack together well and the triglyceride solution is liquid at room temperature. Plants predominately make unsaturated fats and these fats are called "oils" since the unsaturated fats are liquid at room temperature. Animals predominately make saturated fats (e.g., bacon grease) that pack together well (since they have no kinks) and are solid at room temperature.

Unsaturated fats obtained from plants (e.g., corn oil or olive oil) are preferred in the diet over saturated fats. High intake of saturated fats is associated with lower levels of high density lipoprotein (HDL) and higher levels of low density lipoproteins (LDL). HDL is the "good guy" since it removes cholesterol from the blood and high levels of HDL are associated with lower levels of vascular disease. So, saturated fats are associated with higher levels of blood cholesterol and plaque formation on blood vessel walls.

Corn oil margarine is made by changing the double bonds in corn oil to single bonds. High pressure hydrogen gas is pumped into corn oil to force hydrogen atoms onto the carbons of the double bond in the fatty acid (a process called hydrogenation). This breaks the double bond and saturates the carbons with hydrogen. Hydrogenation removes the kinks in the fatty acid chain and allows the triglycerides to pack together well. Thus, you have a solid form that can be spread on toast. However, the industrial process also produces "trans" double bonds in the fatty acids of the triglycerides. These "trans" fats have a double bond (unsaturated) but are straight chains; they are considered as dangerous as the saturated, straight chain fats. That is, trans fats are associated with high levels of blood cholesterol and vascular disease.

In ALD, these VLCSFAs build up in the blood stream up to 2-4 times higher than normal:  hexacosanoic acid (has fatty acids with chains of 26 carbons with no double bonds thus, they are saturated; this is abbreviated "C26:0"), and tetracosenoic acid (C24:0; i.e., fatty acid chains 24 carbons long and saturated- no double bonds).  VLCSFAs are dangerous due to their properties. These fatty acids have a very long hydrophobic tail (the uncharged carbon chain) and a charged carboxyl group at one end.

However, why would very long chain saturated fatty acids induce ALD whereas very long chain unsaturated fatty acids would not? The saturated fatty acid is straight (not crooked) and these characteristics would facilitate the ability of VLCSFAs to interact with, insert into or solubilize the hydrophobic myelin sheath. VLCSFAs may act like a "soap" to solubilize or interact with the hydrophobic molecules of the myelin sheath (for teachers: micelle formation could be discussed here). Soaps make nonsouble dirt molecules become soluble so that they simply float away from your dirty clothes.  Normally, dirt and myelin sheath molecules are not soluble in water (they precipitate on the surface of neurons or stick to your clothes); however, VLCSFA may be able to make these nonsoluble myelin sheath molecules become soluble-- when soluble, the myelin sheath molecules will simply float away from the neurons.  Neurons do not function well without the sheath-- neurons are like wires that need a plastic coating -the myelin sheath- around them to work well (teachers: why do neurons not function well without the insulating myelin sheath?).

However, the solubilizing effect of   VLCSFAs  may not be how they act (or it may not be all of the answer).  The exact mechanism of how VLCSFAs cause ALD symptoms is not known.  As opposed to the solubilizing effect noted above, the properties of VLCSFAs would allow it to concentrate in the myelin sheath and may cause a local immune reaction that destroys the sheath. Conversely, the properties of VLCSFAs may allow it to concentrate in neural membranes to inhibit membrane function (Moser, 1995).