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. Author manuscript; available in PMC: 2015 Jul 7.
Published in final edited form as: Genet Med. 2001 Sep-Oct;3(5):359–371. doi: 10.1097/00125817-200109000-00006

Table 2.

Prevalence of premutation (61–200 repeats) among females and males in the general population adapted from 8

Country Target population No. positive/
No. tested		 Estimated
prevalence (95%
CI):		 Estimated
prevalence
(95% CI):
Females Males Females Males
Canada
(Quebec)60 		Unselected female
blood donors		 28/10,624 - 1/379
(1/560-1/267)		 -
Israel61 Women of
reproductive age with
no family history of
fragile X or MR		 39/10,587 - 1/271
(1/377-1/201)		 -
Israel57 Women of
reproductive age with
no history of fragile X
or MR		 18/8,426 - 1/468
(1/766-1/303)		 -
Finland 63 Pregnant women with
no known history of
fragile X		 6/1,477 - 1/246
(1/605-1/119)		 -
U.K.
(Wessex)41;121 		SpEd population of
boys (ages 5–18
years), unknown
etiology		 - 2/3,732 - 1/1,866
(1/5,376-1/288)
U.S.A.
(Atlanta,
Georgia)38;122 		SpEd population
(ages 7–10 years) and
their parents		 Caucasian: 2/670

African-American: 0/321		 Caucasian: 2/2,016

African-American: 0/805		 Caucasian: 1/335
(1/1,934-1/84)		 Caucasian: 1/1,008
(1/5,814-1/250)
Canada
(Ontario) and
U.S.A.
(Michigan)151 		Guthrie spots from
consecutive male
births		 - 1/1,000 - 1/1,000
(1/19,154-1/210)
Canada
(Winnipeg,
Manitoba)152 		Anonymous,
consecutive newborn
blood spots		 0/735 1/778 - 1/778
(1/14,904-1/163)
U.S.A.
(Fairfax,
Virginia)62 		Screening egg donors
or pregnant women
with no history of MR
or LD		 3/745a - 1/248
(1/961-1/93)		 -
U.S.A.
(Baltimore,
Maryland)153 		Families referred for
genetic disorders		 1/561 0/416 1/561
(1/10,741-1/118)		 -
U.S.A.
(Baltimore,
Maryland)154 		Children (ages 5–18
years) with learning
or school difficulties,
mixed ethnicity		 0/341 1/673 - 1/673
(1/12,892-1/141)
Hellenic
population of
Greece and
Cyprus 130 		Referred clinical
population of
idiopathic MR		 0/176 1/257 - 1/257
(1/4,923-1/54)
U.S.A.
(Colorado)127 		Targeted “high risk”
children (ages 2–18
years with MR,
autism, LD, ADHD,
family history) in
SpEd population		 0/140 1/299 - 1/299
(1/5,727-1/63)
U.S.A.
(Rochester,
Minnesota)155 		Caucasian female
blood donors		 1/197 0/50 1/197
(1/3,774-1/42)		 -

Abbreviations: Special education or special schools (SpEd), mental retardation (MR), learning disability (LD), attention deficit/hyperactivity disorder (ADHD), attention deficit (AD).

a

Spence et al 62 reported one of the premutations as 60±3 repeats.