Unravelling the parental origin and mechanism of formation of the 47,XY,i(X)(q10) Klinefelter karyotype variant.
OBJECTIVE
To describe the parental origin and the mechanism of formation of an 47,XY,idic(X)(p11.2) karyotype in a patient with Klinefelter syndrome.


METHODS
Case report.


METHODS
A university hospital.


METHODS
A 36-year-old man with primary infertility.


METHODS
Genotype-phenotype correlation and microsatellite marker-mediated haplotype analysis subsequent to whole genome amplification of microdissected chromosomes.


METHODS
Genotype-phenotype correlation, mechanism of formation, and parental origin.


RESULTS
Maternal origin of the isochromosome and the normal X chromosome and loss of maternal heterozygosity for all informative Xq markers on the isochromosome and in each case, the presence of the other maternal allele on the normal homologue was shown. Comparative analysis of the clinical features of 17 additional cases and of 1 case with a 46,XY/47,XY,i(X)(q10) karyotype reported in the literature revealed a phenotype very similar to the clinical findings in patients with a 47,XXY karyotype.


CONCLUSIONS
The molecular results in our patient indicate a maternal origin of a true dicentric isochromosome and most likely postzygotic formation subsequent to a nondisjunction in maternal meiosis II. With the exception of the final height the phenotype of Klinefelter syndrome appears not to be the consequence of trisomy of the pseudoautosomal region on Xp.
Höckner
Martina
M
Department of Medical Genetics, Division of Clinical Genetics, Molecular and Clinical Pharmacology, Innsbruck, Austria.
Pinggera
Germar-Michael
GM
Günther
Barbara
B
Sergi
Consolato
C
Fauth
Christine
C
Erdel
Martin
M
Kotzot
Dieter
D
D000328:Adult; D002871:Chromosome Banding; D020223:Chromosome Painting; D041321:Chromosomes, Human, X; D041322:Chromosomes, Human, Y; D005838:Genotype; D006801:Humans; D007248:Infertility, Male / Q000235:genetics*; D018404:Isochromosomes; D007713:Klinefelter Syndrome / Q000235:genetics*; D008297:Male; D010375:Pedigree; D010641:Phenotype