Validation of the multiplex ligation-dependent probe amplification assay and its application on the distribution study of the major alleles of 17 blood group systems in Chinese donors from Guangzhou.

BACKGROUND: Genotyping platforms for common red blood cell (RBC) antigens have been successfully applied in Caucasian and black populations but not in Chinese populations. In this study, a genotyping assay based on multiplex ligation-dependent probe amplification (MLPA) technology was applied in a Chinese population to validate the MLPA probes. Subsequently, the comprehensive distribution of 17 blood group systems also was obtained. STUDY DESIGN AND METHODS: DNA samples from 200 Chinese donors were extracted and genotyped using the blood-MLPA assay. To confirm the MLPA results, a second independent genotyping assay (ID Core+) was conducted in 40 donors, and serological typing of 14 blood-group antigens was performed in 91 donors. In donors who had abnormal copy numbers of an allele (DI and GYPB) determined by MLPA, additional experiments were performed (polymerase chain reaction, sequencing, and flow cytometry analysis). RESULTS: The genotyping results obtained using the blood-MLPA and ID Core+ assays were consistent. Serological data were consistent with the genotyping results except for one donor who had a Lu(a-b-) phenotype. Of the 17 blood group systems, the distribution of the MNS, Duffy, Kidd, Diego, Yt, and Dombrock systems was polymorphic. The Mur and Sta antigens of the MNS system were distributed with a frequency of 9% (18 of 200) and 2% (4 of 200), respectively. One donor with chimerism and one who carried a novel DI*02(A845V) allele, which predicts the depression of Dib antigen expression, were identified. CONCLUSIONS: The blood-MLPA assay could easily identify the common blood-group alleles and correctly predicted phenotype in the Chinese population. The Mur and Sta antigens were distributed with high frequency in a Southern Chinese Han population.

Identification of a novel frequent RHCE*ce308T variant allele in Chinese D- individuals, resulting in a C+c- phenotype.

BACKGROUND: The RHCE allele is highly polymorphic; more than 60 variants have been described leading to diminished expression of C, c, E, and e antigens. Not much is known about the prevalence of RHCE variants in the Chinese population. Individuals carrying a variant are at risk to develop alloantibodies in response to mismatched pregnancy or transfusion. In this study, phenotyping and genotyping of the RHCE allele in Chinese donors revealed a new clinically relevant mutation. STUDY DESIGN AND METHODS: Blood samples from 200 D- and 200 D+ Chinese donors were analyzed by the RH multiplex ligation-dependent probe amplification (MLPA) assay and compared to serologically typed RhCE phenotypes, when available. All exons of the RHCE gene were sequenced in samples with aberrant genotyping results. The phenotype of the new variant RHCE allele was tested by transducing cultured human erythroblasts. RESULTS: Aberrant copy numbers for Exon 2 of the RHCE gene were discovered by MLPA in six D- donors (6/200), but not in D+ donors (0/200). Sequencing of the RHCE gene in these six donors identified a new variant RHCE*ce308C>T (p.103Pro>Leu) allele with an allele frequency of 0.015 within the D- individuals in this study. This variant was not detected in D+ individuals showing linkage with the D- haplotype. Serologically weak C expression and loss of c expression was demonstrated on donor red blood cells. In vitro transfection studies of the RHCE*ce308T variant in cDe/ce and CDe/CDe erythroblasts confirmed that the variant is associated with anti-C reactivity while abolishing c expression. CONCLUSION: Genotyping of individuals carrying this variant by standard RHCE genotyping might falsely predict a C- phenotype or a c+ phenotype. This new variant should be taken into account in RHCE genotyping assays designed for the Chinese population.

Autosomal dominant lateral temporal epilepsy (ADLTE): novel structural and single-nucleotide LGI1 mutations in families with predominant visual auras.

PURPOSE: Autosomal dominant lateral temporal epilepsy (ADLTE) is a genetic focal epilepsy syndrome characterized by prominent auditory or aphasic symptoms. Mutations in LGI1 account for less than 50% of ADLTE families. We assessed the impact of LGI1 microrearrangements in a collection of ADLTE families and sporadic lateral temporal epilepsy (LTE) patients, and investigated novel ADLTE and LTE patients. METHODS: Twenty-four ADLTE families and 140 sporadic LTE patients with no evidence of point mutations in LGI1 were screened for copy number alterations using multiplex ligation-dependent probe amplification (MLPA). Newly ascertained familial and sporadic LTE patients were clinically investigated, and interictal EEG and MRI findings were obtained; probands were tested for LGI1 mutations by direct exon sequencing or denaturing high performance liquid chromatography. RESULTS: We identified a novel microdeletion spanning LGI1 exon 2 in a family with two affected members, both presenting focal seizures with visual symptoms. Also, we identified a novel LGI1 missense mutation (c.1118T > C; p.L373S) in a newly ascertained family with focal seizures with prominent visual auras, and another missense mutation (c.856T > C; p.C286R) in a sporadic patient with auditory seizures. CONCLUSIONS: We describe two novel ADLTE families with predominant visual auras segregating pathogenic LGI1 mutations. These findings support the notion that, in addition to auditory symptoms, other types of auras can be found in patients carrying LGI1 mutations. The identification of a novel microdeletion in LGI1, the second so far identified, suggests that LGI1 microrearrangements may not be exceptional.