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Stepwise partitioning of Xp21: a profiling method for XK deletions causative of the McLeod syndrome


Gassner, Christoph; Brönnimann, Chantal; Merki, Yvonne; Mattle-Greminger, Maja Patricia; Sigurdardottir, Sonja; Meyer, Eduardo; Engström, Charlotte; O'Sullivan, John D; Jung, Hans H; Frey, Beat M (2017). Stepwise partitioning of Xp21: a profiling method for XK deletions causative of the McLeod syndrome. Transfusion, 57(9):2125-2135.

Abstract

BACKGROUND: McLeod syndrome (MLS) is hematologically defined by the absence of the red blood cell (RBC) antigen Kx on the transmembrane RBC protein, XK, representing a highly specific diagnostic marker. Direct molecular assessment of XK therefore represents a desirable diagnostic tool. Whereas pathogenic point mutations may be simply identified, partial and complete deletions of XK on Xp21.1, eventually covering adjacent genes and causing multifaceted "continuous gene syndromes," are difficult to localize.
STUDY DESIGN AND METHODS: Three different McLeod patient samples were tested using 16 initial positional polymerase chain reaction (PCR) procedures distributed over an approximately 2.8-Mbp Xp-chromosomal region, ranging telomeric from MAGEB16 to OTC, centromeric of XK. The molecular breakpoint of one sample with an apparent large Xp deletion was iteratively narrowed down by stepwise positioning further PCR procedures and sequenced. Two mutant XK genes, one previously published and serving as a positive control, were also sequenced.
RESULTS: We confirmed the positive control as previously published and listed as XK*N.20 by the International Society of Blood Transfusion (ISBT). The other XK showed a novel four-nucleotide deletion in Exon 1, 195-198delCCGC (newly listed as XK*N.39 by the ISBT). The third sample had an approximately 151-kbp X-chromosomal deletion, reaching from Exon 2 of LANCL3, across XK to Exon 3 of CYBB (newly listed as XK*N.01.016 by the ISBT). Carrier status of the patients' sister was diagnosed using a diagnostic "gap-PCR."
CONCLUSIONS: The stepwise partitioning of Xp21.1 is pragmatic and cost-efficient in comparison to other diagnostic techniques such as "massive parallel sequencing" given the rarity of MLS. All males with suspected MLS should be considered for molecular XK profiling.

Abstract

BACKGROUND: McLeod syndrome (MLS) is hematologically defined by the absence of the red blood cell (RBC) antigen Kx on the transmembrane RBC protein, XK, representing a highly specific diagnostic marker. Direct molecular assessment of XK therefore represents a desirable diagnostic tool. Whereas pathogenic point mutations may be simply identified, partial and complete deletions of XK on Xp21.1, eventually covering adjacent genes and causing multifaceted "continuous gene syndromes," are difficult to localize.
STUDY DESIGN AND METHODS: Three different McLeod patient samples were tested using 16 initial positional polymerase chain reaction (PCR) procedures distributed over an approximately 2.8-Mbp Xp-chromosomal region, ranging telomeric from MAGEB16 to OTC, centromeric of XK. The molecular breakpoint of one sample with an apparent large Xp deletion was iteratively narrowed down by stepwise positioning further PCR procedures and sequenced. Two mutant XK genes, one previously published and serving as a positive control, were also sequenced.
RESULTS: We confirmed the positive control as previously published and listed as XK*N.20 by the International Society of Blood Transfusion (ISBT). The other XK showed a novel four-nucleotide deletion in Exon 1, 195-198delCCGC (newly listed as XK*N.39 by the ISBT). The third sample had an approximately 151-kbp X-chromosomal deletion, reaching from Exon 2 of LANCL3, across XK to Exon 3 of CYBB (newly listed as XK*N.01.016 by the ISBT). Carrier status of the patients' sister was diagnosed using a diagnostic "gap-PCR."
CONCLUSIONS: The stepwise partitioning of Xp21.1 is pragmatic and cost-efficient in comparison to other diagnostic techniques such as "massive parallel sequencing" given the rarity of MLS. All males with suspected MLS should be considered for molecular XK profiling.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Clinic for Neurology
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:September 2017
Deposited On:07 Dec 2017 18:14
Last Modified:07 Dec 2017 18:14
Publisher:Wiley-Blackwell Publishing, Inc.
ISSN:0041-1132
Publisher DOI:https://doi.org/10.1111/trf.14172
PubMed ID:28555782

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