Association of HTRA1 mutations and familial ischemic cerebral small-vessel disease.
BACKGROUND
The genetic cause of cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL), which is characterized by ischemic, nonhypertensive, cerebral small-vessel disease with associated alopecia and spondylosis, is unclear.


METHODS
In five families with CARASIL, we carried out linkage analysis, fine mapping of the region implicated in the disease, and sequence analysis of a candidate gene. We also conducted functional analysis of wild-type and mutant gene products and measured the signaling by members of the transforming growth factor beta (TGF-beta) family and gene and protein expression in the small arteries in the cerebrum of two patients with CARASIL.


RESULTS
We found linkage of the disease to the 2.4-Mb region on chromosome 10q, which contains the HtrA serine protease 1 (HTRA1) gene. HTRA1 is a serine protease that represses signaling by TGF-beta family members. Sequence analysis revealed two nonsense mutations and two missense mutations in HTRA1. The missense mutations and one of the nonsense mutations resulted in protein products that had comparatively low levels of protease activity and did not repress signaling by the TGF-beta family. The other nonsense mutation resulted in the loss of HTRA1 protein by nonsense-mediated decay of messenger RNA. Immunohistochemical analysis of the cerebral small arteries in affected persons showed increased expression of the extra domain-A region of fibronectin and versican in the thickened tunica intima and of TGF-beta1 in the tunica media.


CONCLUSIONS
CARASIL is associated with mutations in the HTRA1 gene. Our findings indicate a link between repressed inhibition of signaling by the TGF-beta family and ischemic cerebral small-vessel disease, alopecia, and spondylosis.
Hara
Kenju
K
Niigata University, Niigata, Japan.
Shiga
Atsushi
A
Fukutake
Toshio
T
Nozaki
Hiroaki
H
Miyashita
Akinori
A
Yokoseki
Akio
A
Kawata
Hirotoshi
H
Koyama
Akihide
A
Arima
Kunimasa
K
Takahashi
Toshiaki
T
Ikeda
Mari
M
Shiota
Hiroshi
H
Tamura
Masato
M
Shimoe
Yutaka
Y
Hirayama
Mikio
M
Arisato
Takayo
T
Yanagawa
Sohei
S
Tanaka
Akira
A
Nakano
Imaharu
I
Ikeda
Shu-ichi
S
Yoshida
Yutaka
Y
Yamamoto
Tadashi
T
Ikeuchi
Takeshi
T
Kuwano
Ryozo
R
Nishizawa
Masatoyo
M
Tsuji
Shoji
S
Onodera
Osamu
O
D000328:Adult; D000369:Aged, 80 and over; D000505:Alopecia / Q000235:genetics*; D002539:Cerebral Arterial Diseases / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D002536:Cerebral Arteries / Q000473:pathology; D002544:Cerebral Infarction / Q000235:genetics; D005260:Female; D005808:Genes, Recessive; D000074289:High-Temperature Requirement A Serine Peptidase 1; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D010375:Pedigree; D012697:Serine Endopeptidases / Q000235:genetics*; D015398:Signal Transduction; D055009:Spondylosis / Q000235:genetics*; D013577:Syndrome; D014158:Transcription, Genetic; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D017539:Tunica Intima / Q000473:pathology
D016212:Transforming Growth Factor beta; D000074289:High-Temperature Requirement A Serine Peptidase 1; C474012:HTRA1 protein, human; D012697:Serine Endopeptidases