[ABO*A2.08 Subtype Allele Identification and Protein Structure Analysis in Newborns].

OBJECTIVE: To study the serological characteristics of ABO*A2.08 subtype and explore its genetic molecular mechanism. METHODS: ABO blood group identification was performed on proband and her family members by routine serological methods. ABO genotyping and sequence analysis were performed by polymerase chain reaction-sequence specific primer (PCR-SSP), and direct sequencing of PCR products from exons 6 and 7 of ABO gene were directly sequenced and analyzed. The effect of gene mutation in A2.08 subtype on structural stability of GTA protein was investigated by homologous protein conserved analysis, 3D molecular modeling and protein stability prediction. RESULTS: The proband's serological test results showed subtype Ax, and ABO genotyping confirmed that the proband's genotype was ABO*A207/08. Gene sequencing of the proband's father confirmed the characteristic variation of c.539G>C in the 7th exon of ABO gene, leading to the replacement of polypeptide chain p.Arg180Pro (R180P). 3D protein molecular modeling and analysis suggested that the number of hydrogen bonds of local amino acids in the protein structure was changed after the mutation, and protein stability prediction showed that the mutation had a great influence on the protein structure stability. CONCLUSION: The mutation of the 7th exon c.539G>C of ABO gene leads to the substitution of polypeptide chain amino acid, which affects the structural stability of GTA protein and leads to the change of enzyme activity, resulting in the A2.08 phenotype. The mutated gene can be stably inherited.

[Retrospective Analysis of Irregular Antibodies Causing Hemolytic Disease of the Fetus and Newborn in Jiangxi Province].

OBJECTIVE: To analyze the characteristics of antibody-specific distribution, laboratory detection results of hemolytic disease of the fetus and neonatal(HDFN) caused by irregular blood group antibodies other than ABO, and its correlation with the clinical situation. METHODS: The non-ABO-HDFN cases in our hospital from October 2012 to December 2021 were selected as the research objects, and the cases diagnosed with ABO-HDFN in the same period were randomly selected as the control group, and the data of antibody specific distribution, total bilirubin, direct antibodies, maternal history, age of the children, the presence or absence of combined ABO-HDFN, and whether to exchange/transfuse blood were retrospectively analyzed. The characteristics of non-ABO-HDFN in Jiangxi province were analyzed. RESULTS: The detection rate of non-ABO-HDFN in Jiangxi province increased. Among 187 non ABO-HDFN cases, the highest percentage of Rh-HDFN was detected (94.6%). Compared with the control group of ABO-HDFN, the non-ABO-HDFN had higher mean integral value of direct antibody, higher peak total bilirubin, and longer duration. Anti-M-HDFN may have severe disease but the direct antibody weak positive/negative, it was easy missed in clinical and delayed the treatment. There is no correlation between the specificity of irregular antibodies, the sex of the child, the mother's previous childbirth history, the presence or absence of combined ABO-HDFN and the need for blood exchange/transfusion(P>0.05). CONCLUSION: The irregular antibodies of causing non ABO-HDFN in Jiangxi area are mainly Rh blood group system, followed by MNS blood group system. Understanding the characteristics of HDFN disease, serological features and the correlation with clinical indexes will help to detect and treat non ABO-HDFN in time and reduce the risk of complications.

[Identification and Molecular Biology of Variant D Blood Group of RHD*95A Genotype].

OBJECTIVE: To explore the molecular biology of D variant blood group with RHD*95A genotype and the genetic mechanism of its generation. METHODS: A total of 6 samples from 3 generations of a family were analyzed. RHD blood group was identified by saline test tube and microcolumn gel card method. 10 exons of RHD gene were amplified by Polymerase Chain Reaction-Sequence Specific Primer (PCR-SSP) and analyzed by direct sequencing. Homology modeling was used to compare the structural differences between mutant RHD protein and wild-type RHD protein. RESULTS: The proband was identified as D variant by serological identification, RHD gene sequencing directly detected a c. 95 c > A mutation in exon 1 that leads to encoding the 32-bit amino acids by threonine Thr (T) into aspartic acid Asn (N), the rest of the exon sequences were normal compared with the normal RHD*01 gene. In the family, the proband's father, grandmather and uncle were all carried the same RHD*95A allele. Protein modeling results suggested that the hydrogen chain connected to the 32nd amino acid residue was changed after p.T32N mutation, which affected the structural stability of RHD protein. CONCLUSION: The first genetic lineage of the RHD*95A gene was identified in a Chinese population. The c.95C>A mutation in RHD gene was found in the family, which resulted in reduced expression of RHD antigen and showed D variant, the mutation could be stably inheritable. Gene identification and protein structure analysis of D variant population is helpful to explore the molecular mechanism of its formation and ensure the safety of blood transfusion.

[Study on BW.12 Subtype Caused by c.278C>T Mutation in Exon 6 of ABO Gene].

OBJECTIVE: To investigate the effect of ABO gene α-1,3-D galactosyl transferase mutation on B antigen expression and its molecular mechanism. METHODS: The proband and their family members were identified by routine serological methods, and ABO genotyping and sequence analysis were performed by polymerase chain reaction-sequence specificity (PCR-SSP) and direct sequencing of PCR products from exon 1-7 of ABO gene. The 3D structural simulation of mutant proteins was performed by bioinformatics software. The effect of gene mutation on protein structural stability was analyzed. RESULTS: The proband and his family members were subtype B. ABO genotyping indicated that the proband's genotype was Bw12/O. Gene sequencing results confirmed the presence of ABO*BW.12 characteristic variation c.278C>T in the 6th exon of allele B, leading to the replacement of polypeptide chain p.Pro93Leu. The 3D structure simulation analysis of the protein showed that the hydrogen bonds and water molecules connected to the protein changed after amino acid substitution. The family investigation found that the grandfather, father, uncle and brother of the proband all carried the same ABO*BW.12 allele. CONCLUSION: The mutation of the 6th exon c.278C>T of ABO gene led to the substitution of polypeptide chain amino acids, which affected the stability of α-1,3-D galactosyl transferase protein, resulting in the change of enzyme activity, and the Bw.12 phenotype, which can be stably inherited.