SPINAL MUSCULAR ATROPHY (5q)

SMA 5q: General Features

H&E stain	ATPase pH 9.4 stain
Grouped atrophy   Small muscle fibers are often rounded   Pyknotic nuclear clumps are not present. Large muscle fibers are hypertrophied.	Large fibers: Hypertrophied & Type I Small fibers: Type I or II

SMA, Type 2

H&E stain	H&E stain
Large grouped atrophy Clusters of large type I muscle fibers

ATPase, pH 9.4	ATPase, pH 9.4
Small muscle fibers may be varied types (Left) or mostly type II (Right)

ATPase, pH 4.3	NADH
Many small fibers are type IIC	Small fibers stain darkly on NADH

SMA, Type 1

H & E	H & E
Many muscle fibers are small. A few hypertrophied fibers are present

SMA, Congenital (Type 0)

H & E	H & E
Only small muscle fibers are present. Small fibers have moderate variation in size