text: Yo, listen up, I got a story to tell,
  'Bout a condition called Retinitis Pigmentosa, oh well.
  It's a group of retinal degeneration, no joke,
  Loss of vision, night blindness, that's how it goes.
  
  Prevalence? 1-2 in 5,000, that's the deal,
  One of the main causes of blindness, it's real.
  Early and middle life, it hits you hard,
  But let me break it down, playin' my rap card.
  
  Some cases are isolated, about 36-48%,
  But the rest got modes of inheritance, don't forget.
  Autosomal dominant, recessive, or X-linked,
  XLRP, that's the one they detect.
  
  In the UK, 14-22% of RP families be affected,
  XLRP gene(s) got 'em all connected.
  With DNA probes and polymorphisms, they trace,
  Linkage analysis pinpointin' the right place.
  
  L1.28, one of the probes they use,
  Linked to XLRP in five families, no excuse.
  Confidence limits of 0-15 centimorgans, that's tight,
  LOD score of 7.89, we got it right.
  
  The XLRP locus on the X chromosome, it's clear,
  Proximal part of the short arm, ain't no fear.
  This probe can help detect carriers, that's a fact,
  And diagnose early, in 'bout 40% of the pack.
  
  But we gotta analyze more families, just to be sure,
  Exclude genetic heterogeneity, gotta find the cure.
  So that's the story of RP, my rap's complete,
  Shining a light on the science, droppin' knowledge, take a seat.