Development and targeted application of a rapid QF-PCR test for sex chromosome imbalance.
OBJECTIVE
A QF-PCR test has been developed to diagnose sex chromosome imbalances in prenatal samples and has been applied to a diagnostic service.


METHODS
The test uses a PCR multiplex with eight primer pairs: six X-chromosome polymorphic markers, including two markers from Xp (a region not included in previously published sex chromosome aneuploidy tests), one polymorphic marker for a locus common to the long arms of the X and Y chromosomes, and the non-polymorphic amelogenin marker. Homozygosity for all X-chromosome markers and the absence of the Y-chromosome amelogenin marker is highly likely (907 : 1) to represent monosomy X (Turner syndrome), but interphase FISH is always used to confirm such a result.


RESULTS
Blind studies were carried out to validate the test and the first year of clinical use has been reported. Results are usually issued within one working day, and the test is more efficient than interphase FISH.


CONCLUSIONS
The sex chromosome imbalance test has been targeted to prenatal samples displaying a clear ultrasound indication consistent with Turner syndrome, and has also been used to identify fetal sex in pregnancies at risk of inheriting a sex-linked molecular disorder. No misdiagnoses were made. It is concluded that QF-PCR can rapidly and accurately diagnose sex chromosome status and imbalances, reducing maternal anxiety and aiding in efficient pregnancy management.
Donaghue
Celia
C
Cytogenetics Department, Genetics Centre, Guy's and St Thomas' Hospital Trust, 5th Floor Guy's Tower, St Thomas' Street, London SE1 9RT, UK. celia.donaghue@gstt.sthames.nhs.uk
Roberts
Angharad
A
Mann
Kathy
K
Ogilvie
Caroline Mackie
CM
D053523:Amelogenin; D000782:Aneuploidy; D015193:Chorionic Villi Sampling; D041321:Chromosomes, Human, X; D041322:Chromosomes, Human, Y; D003746:Dental Enamel Proteins / Q000235:genetics; D005260:Female; D005819:Genetic Markers; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D016133:Polymerase Chain Reaction / Q000379:methods*; D011110:Polymorphism, Genetic; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D012729:Sex Chromosome Aberrations; D014424:Turner Syndrome / Q000175:diagnosis / Q000235:genetics
D053523:Amelogenin; D003746:Dental Enamel Proteins; D005819:Genetic Markers