Precise diagnosis of a hereditary spherocytosis patient with complicated hematological phenotype.

Hereditary spherocytosis (HS) is one of the most common causes of hereditary hemolytic anemia. The current diagnostic guidelines for HS are mainly based on a combination of physical examination and laboratory investigation. However, some patients present with complicated clinical manifestations that cannot be explained by routine diagnostic protocols. Here, we report a rare HS case of mild anemia with extremely high indirect bilirubin levels and high expression of fetal hemoglobin. Using whole exome sequencing analysis, this patient was identified as a heterozygous carrier of a de novo SPTB nonsense mutation (c.605G > A; p.W202*) and a compound heterozygous carrier of known UGT1A1 and KLF1 mutations. This genetic analysis based on the interpretation of the patient's genomic data not only achieved precise diagnosis by an excellent explanation of the complicated phenotype but also provided valuable suggestions for subsequent appropriate approaches for treatment, surveillance and prophylaxis.

SUPT5H mutations associated with elevation of Hb A2 level: Identification of two novel variants and literature review.

ß-thalassemia is one of the most common monogenic disorders in areas of the tropics and subtropics, which represents a major familial and social burden to local people. The elevated Hb A2 level, generally specified as greater than 3.5 %, is commonly used as a high efficiency index for screening of ß-thalassemia carriers. However, mutations in other genes such as GATA1 and KLF1, could also result in increased Hb A2 level. In this study, we identified two novel variants in the SUPT5H gene: a frameshift mutation (SUPT5H: c.3032_3033delTG, p.M1011Mfs*9) and a nonsense mutation (SUPT5H: c.397C > T, p.Arg133*) in two Chinese individuals. Utilizing a combination of phenotype analysis, bioinformatics analysis, and functional analysis, we deduced that these two variants modified the SUPT5H protein's structure, thereby impacting its function and consequently leading to the heightened Hb A2 level phenotype found in the carriers. Furthermore, through a comprehensive literature review, a mutation spectrum was consolidated for SUPT5H, an investigation into the genotype-phenotype correlation was conducted, and factors known to influence Hb A2 levels were identified. Based on this in-depth understanding, clinicians are better equipped to carry out large scale screenings in regions with high prevalence of ß-thalassemia.

A novel gain-of-function PIP4K2A mutation elevates the expression of ß-globin and aggravates the severity of α-thalassemia.

Haemoglobin H (Hb H) disease (intermediate status of α-thalassemia) shows marked phenotypic variability from asymptomatic to severe anaemia. Apart from the combined ß-thalassemia allele ameliorating clinical severity, reports of genetic modifier genes affecting the phenotype of Hb H disease are scarce which bring inconvenience to precise diagnosis and genetic counselling of the patients. Here, we present a novel mutation (c.948C>A, p.S316R) in the PIP4K2A gene in a female Hb H disease patient who displayed moderate anaemia and a relatively high Hb H level. Haematological analysis in her family members revealed that individuals carrying this mutation have upregulated ß-globin expression, leading to a more imbalanced ß/α-globin ratio and more Hb H inclusion bodies in peripheral red blood cells. According to functional experiments, the mutant PIP4K2A protein exhibits enhanced protein stability, increased kinase activity and a stronger regulatory effect on downstream proteins, suggesting a gain-of-function mutation. Moreover, introduction of the S316R mutation into HUDEP-2 cells increased expression of ß-globin, further inhibiting erythroid differentiation and terminal enucleation. Thus, the S316R mutation is a novel genetic factor associated with ß-globin expression, and the PIP4K2A gene is a new potential modifier gene affecting the α-thalassemia phenotype.

TRIM32 biallelic defects cause limb-girdle muscular dystrophy R8: identification of two novel mutations and investigation of genotype-phenotype correlation.

BACKGROUND: Limb-girdle muscular dystrophy R8 (LGMD R8) is a rare autosomal recessive muscle disease caused by TRIM32 gene biallelic defects. The genotype-phenotype correlation of this disease has been reported poorly. Here, we report a Chinese family with two female LGMD R8 patients. METHODS: We performed whole-genome sequencing (WGS) and Sanger sequencing on the proband. Meanwhile, the function of mutant TRIM32 protein was analyzed by bioinformatics and experimental analysis. In addition, a summary of the reported TRIM32 deletions and point mutations and an investigation of genotype-phenotype correlation were performed through a combined analysis of the two patients and other cases reported in previous literature. RESULTS: The two patients displayed typical symptoms of LGMD R8, which worsened during pregnancy. Genetic analysis by whole-genome sequencing (WGS) and Sanger sequencing showed that the patients were compound heterozygotes of a novel deletion (chr9.hg19:g.119431290_119474250del) and a novel missense mutation (TRIM32:c.1700A > G, p.H567R). The deletion encompassed 43 kb and resulted in the removal of the entire TRIM32 gene. The missense mutation altered the structure and further affected function by interfering with the self-association of the TRIM32 protein. Females with LGMD R8 showed less severe symptoms than males, and patients carrying two mutations in NHL repeats of the TRIM32 protein had earlier disease onset and more severe symptoms than other patients. CONCLUSIONS: This research extended the spectrum of TRIM32 mutations and firstly provided useful data on the genotype-phenotype correlation, which is valuable for the accurate diagnosis and genetic counseling of LGMD R8.