Hirschsprung disease

Congenital
Aganglionic
Megacolon.

Congenital:

not acquired
anomaly that is
during
development of
embryologic life

Aganglionic

Megacolon:

no ganglion cells are
going to be
present in the segment
of the bowel

the colon
is going to be
enlarged (dilated)

Very common (especially in pediatric age group)

M>F (4:1)

more frequent in those with other congenital anomalies, like down
syndrome

Genetics: heterogeneous

50% of familial cases result from inactivating mutations in

RET genes

RET ligands

Pathogenesis

Aganglionic
segment
(in rectum usually)

functional obstruction

Premature death of ganglion cells (another theory )

because this aganglionic segment is not
going to relapse and not going to have peristaltic movement and this with time
leads to progressive dilatation and distention of the proximal colon which has
ganglionic cells (the proximal segment can relapse unlike the affected)

Arrest of the migration of
neural crestderived
cells before reaching the anus

affect the distal colon and starts
from the rectum and goes upward

we won’t havethe Meissner’s
and Auerbach's myenteric plexuses