Autosomal/Recessive: (Familial Hypocalciuric Hypercalcemia)

From a chance mating comes a child,

perfectly formed, that sucks and cries

and then a few days later dies.

A fatal flaw in its receptors kills.

And yet the next time its two parents pair

its sibling thrives to guzzle milk and air

for he has wiser molecules

on half his sites and death is nullified.

The normal and the flawed live side by side

in health with only small degrees of rise

in serum calcium to show what lurks

within the cell's bland skin. Cation works

quite well in those who have one false allele.

But to have two is death! And all because

receptors with the least of flaws,

a single substitute among

six hundred thirteen moieties,

occur by chance or curse.

With one allele, occult disease,

with two, fatality at birth.

• Copyright ©2004 by the American College of Physicians