[UGT1A1 gene mutation spectrum with indirect hyperbilirubinemia in children].

Objective: To explore the relevancy between the uridine diphosphate-glucuronylgly-cosyltransferase 1A1 (UGT1A1) gene mutation and the phenotype of indirect hyperbilirubinemia in children. Methods: Sixteen cases with indirect hyperbilirubinemia who visited the Department of Gastroenterology, Children's Hospital of Nanjing Medical University from July 2013 to November 2019 were retrospectively analyzed and were divided into Gilbert syndrome (GS), Crigler-Najjar syndrome type II (CNS-II), and indirect hyperbilirubinemia groups unexplained by UGT1A1 gene mutations. The differences in gene mutation site information and general clinical data were compared. The association between gene mutation spectrum and bilirubin level was explored by t-test analysis. Results: Ten of the sixteen cases with indirect hyperbilirubinemia had GS, three had CNS-II, and three had indirect hyperbilirubinemia unexplained by UGT1A1 gene mutations. A total of six mutation types were detected, of which c.211G > A accounted for 37.5% (6/16), c.1456T > G accounted for 62.5% (10/16), and TATA accounted for 37.5% (6/16), respectively. Compared with the GS group, the CNS group had early disease onset incidence, high serum total bilirubin (t = 5.539, P < 0.05), and indirect bilirubin (t = 5.312, P < 0.05). However, there was no significant difference in direct bilirubin levels (t = 1.223, P > 0.05) and age of onset (t = 0.3611, P > 0.05) between the two groups. There was no significant correlation between the number of UGT1A1 gene mutations and serum bilirubin levels. Children with c.1456T > G homozygous mutations had the highest serum bilirubin levels. Conclusion: The common pathogenic variants of the UGT1A1 gene sequence are c.1456T > G, c.211G > A, and TATA, indicating that these site mutations are related to the occurrence of indirect hyperbilirubinemia and have important guiding significance for the etiological analysis of indirect hyperbilirubinemia in children.

[Splicing abnormalities caused by a novel mutation in the PHKA2 gene in children with glycogen storage disease type IX].

Objective: Glycogen storage disease type IX (GSD-IX) is a rare primary glucose metabolism abnormality caused by phosphorylase kinase deficiency and a series of pathogenic gene mutations. The clinical characteristics, gene analysis, and functional verification of a mutation in a child with hepatomegaly are summarized here to clarify the pathogenic cause of the disease. Methods: The clinical data of a child with GSD-IX was collected. Peripheral blood from the child and his parents was collected for genomic DNA extraction. The patient's gene diagnosis was performed by second-generation sequencing. The suspected mutations were verified by Sanger sequencing and bioinformatics analysis. The suspected splicing mutations were verified in vivo by RT-PCR and first-generation sequencing. Results: Hepatomegaly, transaminitis, and hypertriglyceridemia were present in children. Liver biopsy pathological examination results indicated glycogen storage disease. Gene sequencing revealed that the child had a c.285 + 2_285 + 5delTAGG hemizygous mutation in the PHKA2 gene. Sanger sequencing verification showed that the mother of the child was heterozygous and the father of the child was of the wild type. Software such as HSF3.1 and ESEfinder predicted that the gene mutation affected splicing. RT-PCR of peripheral blood from children and his mother confirmed that the mutation had caused the skipping of exon 3 during the constitutive splicing of the PHKA2 gene. Conclusion: The hemizygous mutation in the PHKA2 gene (c.285 + 2_285 + 5delTAGG) is the pathogenic cause of the patient's disease. The detection of the novel mutation site enriches the mutation spectrum of the PHKA2 gene and serves as a basis for the family's genetic counseling.

[Functional characterization of SLC12A1 gene variants in 3 patients with Bartter syndrome type â ].

Objective: To clarify the molecular basis of patients with Bartter syndrome type I and explore the therapeutic effect of trafficking-defective variations by chemical chaperone 4-Phenylbutyric acid(4-PBA). Methods: The clinical characteristics, laboratory findings and genetic data of 3 patients diagnosed with Bartter syndrome type I who were admitted to Department of Nephrology, Children's Hospital of Nanjing Medical University from 2017 to 2018 were retrospectively analyzed. Wild type and variant SLC12A1 gene constructs were transiently overexpressed in HEK293 cells. Western blotting was used to detect the expression levels of Na+-K+-2Cl-cotransporter(NKCC2) protein. Immunofluorescent staining was applied to investigate the subcellular localization of NKCC2 protein. In addition, the effect of the chemical chaperone 4-PBA on the expression and localization of the SLC12A1 gene variants was investigated. Unpaired t test was used for statistical analysis of 4-PBA treatment. Results: All the 3 patients (2 males and 1 female), aged 3.0, 4.0 and 1.2 years, respectively. All patients had antenatal onset with polyhydramnios and were born prematurely. After birth, all patients presented with hypochlorine alkalosis accompanied by hypokalemia and hyponatremia. Sequencing analysis revealed that the 3 patients were homozygotes or compound heterozygotes for variants in the SLC12A1 gene. In HEK293 cells, the surface expression of NKCC2 in 3 variants (p.L463S, p.L479V, p.507-510del) are all lower than in wild type (0.718±0.039, 0.287±0.081, 0.025±0.156 vs. 1.001±0.028, t=5.92, 8.35, 30.49, all P<0.01). Moreover, the total protein expression of p.L479V and p.507-510del group were all lower than that in wild type group (0.630±0.032, 0.043±0.003 vs. 1.000±0.111, t=3.21, 8.65, all P<0.05). 4-PBA treatment increased the mature protein expression level of the p.L463S and p. L479V group in 4-PBA treatment group are all higher than the untreated group (0.459±0.018 vs. 1.123±0.024, 0.053±0.012 vs. 1.256±0.037, t=2.75, 18.35, all P<0.05). Cytoplasmic retention of the L479V and 507-510del variants were observed by immunofluorescent staining. 4-PBA treatment could rescue a number of NKCC2 L479V variants to the membrane. Conclusions: The 3 SLC12A1 variants cause expression or subcellular localization defects of the protein. The findings that plasma membrane expression and activity can be rescued by 4PBA might help to develop novel therapeutic strategy for Bartter syndrome type Ⅰ.

[Phenotype and genotype analysis of 55 children patients with Wilson's disease].

Objective: To understand the clinical phenotype and spectrum of ATP7B gene mutation in children with Wilson's disease (WD). Methods: A total of 55 cases diagnosed with WD at the Children's Hospital Affiliated to Nanjing Medical University from June 2012 to June 2018 were taken as the research subject. ATP7B gene point mutation was detected by direct sequencing after PCR amplification. Heterozygous mutation in children was discovered by sequencing. Furthermore, the long segment mutation of exon was analyzed by multiplex ligation-dependent probe amplification (MLPA). Results: All 55 WD children had varying degree of liver damage symptoms. Among them, 2 cases had combined neurological symptoms. The positive rates of K-F ring (21%), 24-hour urine copper (97.7%), and ceruloplasmin were all abnormal. The results of ATP7B gene had identified 8 homozygous, 41 compound heterozygous and 6 heterozygous in 55 cases. Direct sequencing method had detected ten cases of ATP7B heterozygotes. In addition, MLPA analysis showed that other allele in four cases had a deletion of the ATP7B gene exon. In all cases, 35 different ATP7B gene mutations were detected, including 23 missense mutations, 3 frameshift mutations, 4 nonsense mutations, 3 exon deletions and 2 splicing changes. The most common allele mutation was c.2333G > T/p.R778L in exon 8, with an allele frequency of 36.54%, followed by c.2975C > T/p.P992L in exon 13, with an allele frequency of 14.42%. Conclusion: ATP7B gene c.2333G > T/p.R778L and c.2975C > T/p.P992L mutations are the most common mutations in children with WD in China. WD patients report shows that there are three long deletion mutations in the exon of the ATP7B gene. For WD children whose DNA sequencing is heterozygous ATP7B gene, it is suggested to further use MLPA method to detect deletion mutations of exons.

Microsurgical anatomy of the lateral skin flap of the leg.

The blood supply, venous drainage, and innervation of the lateral skin flap of the leg were studied in 52 fresh specimens by dissection, angiography, and selected injection of cutaneous arteries with india ink. This flap has a long vascular pedicle that contains the peroneal artery and vein and their branches. The diameter of the peroneal artery is about 3.7 mm. There are 4 to 7 cutaneous branches that penetrate the posterior intermuscular septum and widely anastomose with each other in the subcutaneous tissue. The skin area supplied by the peroneal artery measures approximately 32 X 15 cm. There are 2 sets of veins in the flap: (1) 2 deep veins, the peroneal veins, are about 4 mm in diameter, and (2) a superficial vein, the small saphenous vein, is about 3.3 mm in diameter. The cutaneous nerve is the lateral sural cutaneous nerve. This new lateral skin flap of the leg may be used either as a free flap or as a cutaneous flap and has been proven successful clinically.