Unique unbalanced X;X translocation (Xq22;p11.2) in a woman with primary amenorrhea but without Ullrich-Turner syndrome

Complex X chromosome rearrangement associated with multiorgan autoimmunity

BACKGROUND

Turner syndrome, a congenital condition that affects 1/2,500 births, results from absence or structural alteration of the second sex chromosome. Turner syndrome is usually associated with short stature, gonadal dysgenesis and variable dysmorphic features. The classical 45,X karyotype accounts approximately for half of all patients, the remainder exhibit mosaicism or structural abnormalities of the X chromosome. However, complex intra-X chromosomal rearrangements involving more than three breakpoints are extremely rare.

RESULTS

We present a unique case of a novel complex X chromosome rearrangement in a young female patient presenting successively a wide range of autoimmune diseases including insulin dependent diabetes mellitus, Hashimoto's thyroiditis, celiac disease, anaemia perniciosa, possible inner ear disease and severe hair loss. For the genetic evaluation, conventional cytogenetic analysis and FISH with different X specific probes were initially performed. The complexity of these results and the variety of autoimmune problems of the patient prompted us to identify the exact composition and breakpoints of the rearranged X as well as methylation status of the X chromosomes. The high resolution array-CGH (assembly GRCh37/hg19) detected single copy for the whole chromosome X short arm. Two different sized segments of Xq arm were present in three copies: one large size of 80,3 Mb from Xq11.1 to Xq27.3 region and another smaller (11,1 Mb) from Xq27.3 to Xq28 region. An 1,6 Mb Xq27.3 region of the long arm was present in two copies. Southern blot analysis identified a skewed X inactivation with ≈ 70:30 % ratios of methylated/unmethylated fragments. The G-band and FISH patterns of the rearranged X suggested the aspect of a restructured i(Xq) chromosome which was shattered and fortuitously repaired. The X-STR genotype analysis of the family detected that the patient inherited intact maternal X chromosome and a rearranged paternal X chromosome. The multiple Xq breakages and fusions as well as inverted duplication would have been expected to cause a severe Turner phenotype. However, the patient lacks many of the classic somatic features of Turner syndrome, instead she presented multiorgan autoimmune diseases.

CONCLUSIONS

The clinical data of the presented patient suggest that fragmentation of the i(Xq) chromosome elevates the risk of autoimmune diseases.

Translocation t(X;11)(q22;q25) in a woman with premature ovarian failure

Genetic, autoimmune, environmental, iatrogenic, and idiopathic factors are known to cause premature ovarian failure (POF). This report describes an X;11 translocation, t(X;11)(q22;q25), in a woman diagnosed with POF. The FSH level was found to be elevated. Menstrual cycle was regular initially, and she had a spontaneous abortion at the 5th month of gestation at 16 years of age. Her mother was karyotypically normal while her father was not investigated. Male carriers of X;autosome translocations are mostly infertile, and hence the translocation is presumed to be of de novo origin. Fluorescence in situ hybridization using whole chromosome paint probes confirmed the rearrangement.

Parental origin and mechanism of formation of a 46,X,der(X)(pter-->q21.1::p11.4-->pter)/45,X karyotype in a woman with mild Turner syndrome

OBJECTIVE

To describe the parental origin and the mechanism of formation of a 46,X,der(X)(pter-->q21.1::p11.4-->pter)[23]/45,X[8] karyotype in a patient with mild Turner syndrome.

DESIGN

Case report.

SETTING

A university hospital.

PATIENT(S)

A 23-year-old woman with normal height, gonadal dysgenesis, and mild Turner stigmata.

INTERVENTION(S)

Genotype-phenotype correlation, array-based copy number analysis, fluorescence in situ hybridization with locus-specific probes, and microsatellite marker-mediated haplotype analysis subsequent to whole genome amplification of microdissected chromosomes.

MAIN OUTCOME MEASURES

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

RESULT(S)

Formation in paternal meiosis by refolding in itself and unequal recombination between Xp and Xq were found as the most likely mechanism of formation.

CONCLUSION(S)

Formation of der(X) chromosomes in females can be more complex than previously thought. The nearly normal height of this patient could be explained by a combination of trisomy of the Xp-located SHOX gene and mosaicism with a 45,X cell line.

Premature ovarian failure in a patient with a complex chromosome rearrangement involving the critical region Xq24, characterized by analysis using fluorescence in situ hybridization by chromosome microdissection

OBJECTIVE

To characterize a complex chromosome rearrangement previously detected by G-banding in peripheral blood lymphocytes as 46,X, inv(X)(p11;q2?), inv(4)(q?),ins(8)(q?) in a patient with primary amenorrhea.

DESIGN

Case report.

SETTING

University faculty of medicine and hospital.

PATIENT(S)

A 16-year-old girl with primary amenorrhea.

INTERVENTION(S)

Microdissection of chromosomes labeled by fluorescence in situ hybridization and by reverse painting.

MAIN OUTCOME MEASURE(S)

Use of commercial whole-chromosome painting probes for the detection of the aberrant chromosomes 4, 8, and X. Fluorescence probes of the isolated derivative chromosomes are self-generated.

RESULT(S)

The use of whole-chromosome painting probes allowed reliable identification of all chromosomes involved in the complex chromosome rearrangements. The DNA of those chromosomes was amplified and fluorescence labeled by polymerase chain reaction using degenerated oligonucleotide primers. These probes revealed breakpoints of the complex chromosome rearrangement by hybridization on normal and original chromosomes in 4q31.1, 8q24.1, Xp22.1, Xp11.4, and Xq24.

CONCLUSION(S)

We report on an Indian patient who has premature ovarian failure with primary amenorrhea as well as a hormone level increased for LH and FSH but decreased for TSH. She has a balanced complex translocation with three breakpoints in the X chromosome that were located by fluorescence in situ hybridization by chromosome microdissection, but no breakpoints localized in the critical regions for premature ovarian failure on the X chromosome. The breakpoint in Xq24 may be associated with the amenorrhea.

Primary amenorrhea in a woman with a cryptic complex chromosome rearrangement involving the critical regions Xp11.2 and Xq24

OBJECTIVE

To characterize a complex chromosome rearrangement (CCR) previously detected by G-banding in peripheral blood lymphocytes, as 46,X,-2,-11,-22,-X,+mar 1+mar2+mar3+mar4 in a patient with primary amenorrhea.

DESIGN

Case report.

SETTING

University faculty of Medicine and hospital.

PATIENT(S)

A 36-year-old woman with primary amenorrhea.

INTERVENTION(S)

Fluorescence in situ hybridization (FISH).

MAIN OUTCOME MEASURE(S)

Use of commercially available M-FISH probe (24 colors simultaneously) and whole chromosome painting probes for chromosomes 2, 11, 22, and X to characterize the CCR.

RESULT(S)

The use of conventional and multiple FISH allowed the redefinition of the CCR, showing a cryptic insertion of chromosome 11 in marker 3 previously suspected by M-FISH. The combination of G-banding and FISH data revealed that four chromosomes and seven breakpoints, including 2q21, 2q31, 11q22.1, 11q22.3, 22q13.3, Xp11.21, and Xq24, were implicated in this CCR.

CONCLUSION(S)

This report confirms the importance of a combination of G-banding and FISH (M-FISH and conventional FISH) techniques to characterize the de novo CCR. These techniques also were useful in defining two possible critical chromosome regions, Xp11.21 and Xq24, in which genes of potential interest for a primary amenorrhea could be located.