The Sistine Madonna, Raphael, 1513–14 | Public Domain

In the above painting, one of the figures has a common congenital disability. Can you see it? I will give you some hints…

• Anne Boleyn and Taye Diggs were rumored to have this condition.
• Today, it is easily corrected with surgery, usually at birth.
• It would make someone really good at piano or knitting.
• Research even shows that this congenital disability gives someone augmented motor abilities.
• Those cherubs at the bottom know the answer.

I will give you a minute.

Or two.

Because I know you have nothing better to do.

Except maybe click on the next article, so…

The Sistine Madonna — detail, Raphael 1513–14 | Public Domain

Now, you can’t unsee it. Pope Sixtus has a sixth finger. The condition, called hexadactyly, means six digits. (Polydactyl refers to when the extra digit is a finger.)

Raphael seemed to add extra digits to many of his subjects. In The Engagement of the Virgin Mary, he is up to his old tricks. Can you spot the extra digit?

Spozalizio (The Engagement of Virgin Mary), Raphael 1504 | Public Domain

Some more hints…

• Oddly, this one body part is unclothed.
• The misses is in for some surprises on her wedding night.
• The stick-breaking guy knows.

Do you see it?

I will give you another minute.

Because you love this game.

Unless your wrists and patience are worn out, so…

Spozalizio — detail, Raphael 1504 | Public Domain

The man in the green robe either has a nasty bunion or an extra toe. Did Raphael suck at painting feet and hands or is he purposely adding extra digits again?

Obviously, Raphael was a master draftsman, so we can assume he knew how to draw hands and feet. One theory is that Raphael added a sixth finger to Pope Sixtus (first image) as a play on words. Another theory is that a sixth digit implied the subject had a sixth sense.

But during the Renaissance, artists typically portrayed subjects as realistically as possible. So it is doubtful Raphael was adding extra digits to be clever.

Some physicians have argued that Raphael was not giving his subjects extra digits but portraying a common Renaissance illness — gout. Gout commonly causes the skin to bulge. So the bump next to his baby toe could be a “gouty pouch.”

Mona Lisa, Leonardo da Vinci, date | Public Domain

Mona Lisa

Everyone usually focuses on Mona Lisa’s enigmatic smile. But Vito Franco, a Sicilian professor of pathological anatomy, believes this painting holds another secret — “La Gioconda” suffered from high cholesterol.

He came to this diagnosis after noticing fatty acid buildups on her left eyelid — called xanthelasma. You will also notice that she has a small lipoma on her right hand. A lipoma is a benign fatty tissue tumor common in those with high cholesterol.

The Ugly Duchess or “A Grotesque Old Woman,” Quentin Matsys, 1513 | Public Domain

The Ugly Duchess by Quentin Matsys

The woman is so unfortunate looking that historians once believed she was a caricature. But since Matsys did not have much of a sense of humor, there’s something more nefarious going on. Sadly, this woman probably really looked like this.

The Duchess is suffering from the final stages of Paget’s disease. Paget disease is a chronic bone disorder that causes enlarged and misshapen bones.

This painting was later copied by Leonardo da Vinci and became the inspiration for the Duchess in Lewis Caroll’s Alice Adventures in Wonderland.

Detail from School of Athens, Raphael, 1511 | Public Domain

The School of Athens by Raphael

Here we go…Raphael is at it again. But now he is painting lumpy knees. The person with the mangled knees is believed to be Raphael’s grumpy nemesis, Michelangelo.

Vito Franco believes that Michelangelo’s bulbous knees are a sign of kidney stones. Michelangelo complained about kidney stones or what he called “gravel in his urine” throughout his life. He was diagnosed at the age of 75 and was told to drink medicinal water to pass the stones.

Rheumatologist Sara E. Walker believes Michelangelo’s knobby knees were due to gout. Michelangelo was diagnosed with gout in 1555. And in one of his many letters, he complains of foot pain at the age of 80.

The Tête à Tête, William Hogarth, 1743 | Public Domain

The Tête à Tête by William Hogarth

Before tabloid magazines and Twitter feeds, William Hogarth used his painting to poke fun at the elite. And as the middle class grew, wealthy merchants could purchase prints of his paintings and enjoy roasting aristocrats.

In The Tête à Tête (face to face), Hogarth is satirizing the venality of the marriage market. The painting tells the tale of the “Squanderfields” — an aristocratic family who must marry their entitled son to a wealthy merchant’s daughter because they have “squandered” all their wealth. The young Mr. Squanderfield (the man seated on the right) has come home after a night of wenching. (The dog is giving him away by pulling at a lady’s handkerchief in his pocket.)

But Mr. Squanderfield has worse problems than having to marry for money. Can you spot the deadly infectious disease Mr. Squanderfield suffers from?

Here’s a close-up. Is that a hole in his throat or a gigantic beauty mark?

The Tête à Tête — detail, William Hogarth, 1743 | Public Domain

Or perhaps Mr. Squanderfield should stop visiting prostitutes. The black mark on his throat is the first sign of syphilis — a disease that ravaged most of Europe in the eighteenth century. One in five Londoners had syphilis by the age of 35.

He has the black mark at another point in the series — The Inspection.

The Inspection — detail, William Hogarth, 1743 | Public Domain

This lass also has it.

The Inspection — detail, William Hogarth, 1743 | Public Domain

Now you can play “spot the syphilis marks in eighteenth-century prints.” You’re welcome.

Christina’s World by Andrew Wyeth

It’s a painting that has bewildered art lovers. Why is Christina’s back to the viewer? Is the dilapidated farmhouse her home? And most puzzling, why is she awkwardly arranged on the ground, staring off into the distance?

The painting portrays Anna Christina Olson — a neighbor and favored muse of Wyeth. He painted her several times. (He used his twenty-six-year-old wife as a model for the girl’s head and torso.)

Christina is not just dreamily lying on the grass. She suffered from Charcot-Marie Tooth (CMT) disease — a progressive nerve disease that causes weakness in the lower legs and feet. Sadly, Christina was paralyzed from the waist down and had to move across her farm by crawling. Wyeth said of the painting that he intended to depict someone “limited physically but by no means spiritually.” Perhaps that is why the painting has become so iconic.

Self-portrait with Gold Chain, Rembrandt, 1633 | Public Domain

Rembrandt’s wandering eye

In the above portrait, the right eye looks straight at the viewer, but the left eye looks off to the side. According to Margaret S. Livingstone, a professor of neurobiology at Harvard Medical School, Rembrandt may have had a wandering eye or strabismus. When Livingstone examined 24 of Rembrandt’s self-portraits, she found 23 had the same wandering eye.

Interestingly, Rembrandt’s strabismus may have given him an advantage as an artist. A wandering eye may make it harder to judge depth — called stereoblindness. But that condition also makes it easier to translate 3D objects into a 2D space. (This is also why art teachers tell students to close one eye when observing a subject.)

The Nobleman with his Hand on his Chest, El Greco, 1580 | Public Domain

The Nobleman with his Hand on his Chest by El Greco

El Greco’s work is always recognizable by the elongated limbs and dark palette. But some physicians believe that El Greco’s unique style comes from suffering from Marfan’s syndrome.

Marfan’s syndrome is a rare genetic disorder that affects the body’s connective tissue. Sufferers are often slender because the disease causes limbs to lengthen. In the portrait above, the man’s face and fingers are longer than normal. El Greco consistently painted most of his subjects with these features.

While it’s true that artists often put a little of themselves into every portrait, I am a bit more incredulous with this one. El Greco also could have painted slender people because it appealed to him stylistically.