Table 1.

Intermediate filament proteins

Type	Proteins	Expression Cell Compartment	Examples of Associated Diseases
I	K9–K28; K31–K40 (hair and nails)	Epithelial tissues for K1–K28	EBS (K5/K14); predisposition to acute or chronic liver disease (K8/K18/K19)
II	K1–K8; K71–K86 (hair and nails)	(obligate type I–II heteropolymers)
III	Vimentin	Mesenchymal cells, including lens	Cataracts
	GFAP	Glial cells	Alexander disease
	Desmin	Muscle cells	Desmin-related myopathy
	Syncoilin	Muscle cells	Unknown
	Peripherin	Peripheral neurons	Amyotrophic later sclerosis
IV	Neurofilaments (light, medium, and heavy: NF-L, NF-M, and NF-H)	CNS neurons	CMT type 2; amyotrophic lateral sclerosis (predisposition)
	α-Internexin	CNS neurons	Unknown
	Nestin	Stem and neuroepithelial cells	Unknown
	Synemin	Muscle cells	Unknown
V	Lamins	Nuclei	FPLD2 (lamin A/C); APL (lamin B2)
VI	Bfsp1 (filensin); Bfsp2 (CP49)	Eye lens	Juvenile-onset cataracts

For some of the IFs, only a few examples of associated diseases are listed (e.g., many other keratinopathies and laminopathies are not included, but none of these disorders are known to involve digestive organs).

APL, acquired partial lipodystrophy; Bfsp, beaded filament structural protein; CMT, Charcot-Marie-Tooth disease; CNS, central nervous system; CP49, cytoskeletal protein 49 kDa; EBS, epidermolysis bullosa simplex; FPLD2, Dunnigan familial partial lipodystrophy type 2; K, keratin.