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Human Genome Epidemiology: A Scientific Foundation for Using Genetic Information to Improve Health and Prevent Disease

 

 


Part IV:
CASE STUDIES:  Using Human Genome Epidemiology Information to Improve Health


 

Chapter 23 Tables


Fragile X Syndrome: Application of Gene Identification to Clinical Diagnosis and Population Screening

Dana Crawford, Stephanie L. Sherman



Table 23-1
Population-based prevalence of the fragile X syndrome among males

Country
Target Population
No. Positive / No. tested
Estimated prevalence
Target population %
General population (95% CI)
U.K. (Wessex) 18;35
SpEd population (ages 5-18 years), unknown etiology
20/3,738
SpEd: 0.5
1/5,530
(1/8,992-1/4,007)
U.S.A. (Atlanta, Georgia)28;34
SpEd population (ages 7-10 years), regardless of etiology
White: 4/1,572

African-American: 3/752

Total: 7/2,740
White SpEd: 0.3


African-American SpEd: 0.4


Total SpEd: 0.3
White: 1/3,717 (1/7,692-1/1,869)

African-American: 1/2,545 (1/5,208-1/1,289)

Total:1/3,623 (1/5,988-1/2,212)
Southwest Netherlands19
Schools and institutes for MR, unknown etiology
9/866
Mild MR: 2.0
Moderate/Severe MR: 2.4
1/6,045
(1/9,981-1/3,851)
Hellenic Population of Greece and Cyprus30
Referred clinical population of idiopathic MR
8/611
MR: 1.3
1/4,246 (1/16,440-1/1,333)
Australia (Sydney)95;96
Children with MR in SpEd
10/472
MR: 2.1
Mild MR: 0.6
Moderate/Severe MR: 5.
1/4,350a
Southern Häme, Finland97
Adult males (>16 years) registered in the Southern Häme Care Organization with MR, unknown etiology
6/344
MR: 1.7
1/4,400b
U.K. (Coventry)96;98;99
Children with MR in institutions or SpEd
6/219
MR: 2.7
Mild MR: 1.3
Moderate/Severe MR: 6.7
1/4,090a
Poland (Warsaw)100
Males in institutions or SpEd with MR
6/201
MR: 3.0
1/2,857-1/5,882c
U.K. (Wessex) 29
SpEd population (ages 5-18 years), unknown etiology
4/180
SpEd: 2.2
1/8,918d
Spain101
Children in SpEd or clinically referred with MR of unknown etiology; no known family history of MR
5/180
MR: 2.7
1/6,200-1/8,200e
Guadeloupe, French West Indies31
SpEd population, unknown etiology
11/163
SpEd: 6.7
1/2,359
(1/4,484-1/276)
U.K. (Oxfordshire)102
Children in schools for moderate to severe learning difficulties, unknown etiology
4/103
MR: 3.9
1/4,130f

Abbreviations: Special education or special schools (SpEd), mental retardation (MR).
aTurner et al.96provided only a point estimate.
bArvio et al.97provided only a range on the basis of past cytogenetic and DNA-based diagnoses.
cMazurczak et al.100provided only a range, not a point estimate.
dJacobs et al.29provided only a point estimate.
eMillan et al.101provided a range, not a point estimate. Millan et al.101also acknowledged that persons with mild MR might have been missed, so the range could be as high as 1/5,000-1/6,800.
fSlaney et al.102only provided a lower boundary, not a point estimate.
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Table 23-2
Prevalence of premutation among females in the general population

Country
Target Population
No. tested
Prevalence
(95% CI)a
Prevalence
(95% CI)a

(61-200 repeats)
(55-200 repeats)
Israel33;89
Women of reproductive age with no family history of fragile X or MR
14,334
1/231
(1/299-1/182)
1/116
(1/138-1/97)
Canada (Quebec)38
Unselected female blood donors
10,624
1/379
(1/560-1/267)
1/259 (1/373-1/198)
Israel37
Women of reproductive age or pregnant women
9,660
-
1/159
(1/205-1/124)
Israel32
Women of reproductive age with no history of fragile X or MR
8,426
1/468
(1/766-1/303)
1/145
(1/189-1/113)
Finland87
Pregnant women with no known history of fragile X
1,477
1/246
(1/605-1/119)
-
U.S.A. (Fairfax, Virginia)85
Screening egg donors or pregnant women with no history of MR or LD
745
1/248b
(1/961-1/93)
1/149c
(1/404-1/68)
U.S.A. (Atlanta, Georgia) 28;34
SpEd population (ages 7-10 years)
White: 670

African-American: 321
White: 1/335 (1/1,934-1/84)

African-American: 0/321
-

Abbreviations: mental retardation (MR), learning disability (LD), special education (SpEd).
a Because the frequency of premutations is close to zero, 95% confidence intervals were calculated using the equations recommended by Fleiss103.
b Spence et al.85 reported one premutation as 60±3 repeats.
c Spence et al.85 reported one premutation at 52±3 repeats and one as 55±3 repeats.

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