#ExistInterpData>Fragile X (FMR1) Diagnostic, Fetal
Characteristics: Fragile X syndrome, the most common heritable form of mental retardation, is characterized by moderate mental retardation in males and mild mental retardation in females, hyperactivity, perseverative speech, social anxiety, poor eye contact, hand flapping or biting, autism spectrum disorders behavioral phenotype, and connective tissue anomalies. Adult males may have physical findings including: macroorchidism, a long narrow face, prominent ears and jaw, and a single palmar crease.
Incidence: 1 in 4,000 Caucasian males and 1 in 8,000 Caucasian females; unknown in other ethnicities
Inheritance: X-linked dominant.
Penetrance: Reduced in females.
Cause: Expansion of the FMR1 gene CGG triplet repeat.
Full mutation: >200-230 CGG repeats (methylated)
Premutation: 55-200 CGG repeats (unmethylated)
Intermediate: 45-54 CGG repeats (unmethylated)
Normal: 5-44 CGG repeats (unmethylated)
Clinical Sensitivity: 99 percent.
Methodology: PCR and Southern blot hybridization. Methylation analysis is performed to distinguish between premutation and full mutation alleles. The sex chromosome gene amelogenin is used to confirm gender but also may indicate the possibility of X chromosome aneuploidies such as Klinefelter or Turner syndrome.
Analytic Sensitivity and Specificity: 99 percent
Limitations: Analytic sensitivity may be compromised by PCR primer site mutations.
For quality assurance purposes, ARUP Laboratories will confirm the above result at no charge following delivery. Order Confirmation of Fetal Testing and include a copy of the original fetal report (or the mother's name and date of birth) with the test submission. Please contact an ARUP genetic counselor at (800) 242-2787 extension 2141 prior to specimen submission.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online at www.aruplab.com.
See Compliance Statement C: www.aruplab.com/CS
||Number of CGG Repeats
||81244; Fetal Cell Contamination (FCC): 81265
||Cytogenetics, High Resolution & Fragile X DNA ( Fragile X (FMR1) Diagnostic, Fetal)
, High Resolution & Fragile X DNA ( Fragile X (FMR1) Diagnostic, Fetal)
, Inherited Mental Retardation ( Fragile X (FMR1) Diagnostic, Fetal)
, Martin-Bell Syndrome ( Fragile X (FMR1) Diagnostic, Fetal)