The structure and function of serpins

MUTATIONS AT FRAGILE SITES
34
Also of interen are the chmmosomal suroundingr ofthe frag.
ile riter By characfetiting genetic makers doie 10 the fragile
riter, the gmup hopes to idemay makes or gmups of makers
that are Co-inhemed with unnuble rnei. Thur. the Salisbury
nvdy II a 1hree.pmnged invenigation: how is repeal innabilny
Iinkd 10 the number ofrepeats. 10 the inteml mur re of
the repeats and 10 the chmmosomal comext afthe fragile riter
THE FIRST THOUSAND
A preliminav anslyrii of the first IWO children has jus been
F R A G C L E X SYNDROME
FRAXA sile, and the allela cm%d by an individual at these But phapr the mon im'guing dixovay concas mdiualr
mahrriterpmvide acharacleridc'labd'oflhntchmmo with?~pennumbabortki(ine~~~andprrmu.
soma1 region. The mon common pmem at F W 7-3-4+ tation. Thse allder have bem sdgned to a newgoup. the
(each number representing the allele at each maker rite). il 'intemediale' allder (40-60 repals). In the Fm IWO boy.
iamed by mughly halithe population. In irapile X indiduais
this and previous mdiei haw uncaverd a &d over
reprerentation Ofthree pallerns - 2-1-3 and the related
64-9 and 6-44 These chmoroml typer thus seem to
c~ntiln FRAXA sites prediipsed 10 mutation.
The 2-1-3 FRAXA d e LI pmbably unmble because it cdnr
a relatively large number of CCG repeats. The 6-4-5 and
6-44 pli?. by tonMn. caw 1 nmcfural change: tw, dthe
AGG impuntier M reparaed by more than 10 CGCr and this
may mnder FRAXA suscepuble to full mmtbn. i?tenningif,
about a third oiFRAXA cale$ involve maker combination$
x