[Identification of a novel pathogenic mutation in PDHA1 gene for pyruvate dehydrogenase complex deficiency].

OBJECTIVE: To study the molecular genetic mechanism and genetic diagnosis of pyruvate dehydrogenase complex deficiency (PHD), and to provide a basis for genetic counseling and prenatal genetic diagnosis of PHD. METHODS: Polymerase chain reaction (PCR) was performed to amplify the 11 exons and exon junction of the PDHA1 gene from a child who was diagnosed with PHD based on clinical characteristics and laboratory examination results. The PCR products were sequenced to determine the mutation. An analysis of amino acid conservation and prediction of protein secondary and tertiary structure were performed using bioinformatic approaches to identify the pathogenicity of the novel mutation. RESULTS: One novel duplication mutation, c.1111_1158dup48bp, was found in the exon 11 of the PDHA1 gene of the patient. No c.1111_1158dup48bp mutation was detected in the sequencing results from 50 normal controls. The results of protein secondary and tertiary structure prediction showed that the novel mutation c.1111 _1158dup48bp led to the duplication of 16 amino acids residues, serine371 to phenylalanine386, which induced a substantial change in protein secondary and tertiary structure. The conformational change was not detected in the normal controls. CONCLUSIONS: The novel duplication mutation c.1111_1158dup48bp in the PDHA1 gene is not due to gene polymorphisms but a possible novel pathogenic mutation for PHD.

[Gene mutations and clinical manifestations in children with glycogen storage disease type Ib].

OBJECTIVE: Glycogen storage disease type Ib (GSDIb) is caused by a deficiency of glucose-6-phosphate translocase (G6PT) activity due to SLC37A4 gene mutations. Most GSDIb patients have recurrent infections and inflammatory bowel disease, with poor prognosis. Detection of SLC37A4 gene mutations is of great significance for the diagnosis, subtyping and outcome prediction of GSD patients. This study aims to analyze SLC37A4 gene mutations in Chinese GSDIb patients and to investigate the relationship between its genotypes and clinical manifestations. METHODS: All exons and their flanking introns of SLC37A4 gene in 28 Chinese children with a primary diagnosis of GSDIb were screened by PCR combined with direct DNA sequencing to detect SLC37A4 gene mutations. RESULTS: Five SLC37A4 gene mutations were detected in 7 (25%) of the 28 children, i.e., p.Gly149Glu (9/13, 69%), p.Gly115Arg (1/13, 8%), p.Pro191Leu (1/13, 8%), c.959-960 insT (1/13, 8%) and c.870+5G>A (1/13, 8%). CONCLUSIONS: In this study, c.959-960 insT is a novel mutation and p.Gly149Glu is the most common mutation. p.Gly149Glu may be associated with severe infections in children with GSDIb.

Incidence tendency, etiological classification and outcome of congenital hypothyroidism in Guangzhou, China: an 11-year retrospective population-based study.

OBJECTIVES: An increased incidence of congenital hypothyroidism (CH) has been described worldwide over the years. In this study, we aimed to investigate the epidemiologic characteristics of CH, the iodine status in Guangzhou, China and to investigate which factors might influence the CH incidence during the period 2010-2020. METHODS: We retrospectively reviewed all cases of CH detected by newborn screening during the period 2010-2020. CH was classified as either suspected thyroid dyshormonogenesis (SDH) or thyroid dysgenesis (TD) based on thyroid ultrasound at first diagnosis. Patients were re-evaluated after 4 weeks of L-thyroxine withdrawal at age of 2-3 years to confirm the diagnosis of permanent CH (PCH) or transient CH (TCH). RESULTS: From 2010 to 2020, 1,655 patients with CH were confirmed from 2,400,383 newborns (1:1,450). The CH incidence increased from 1:2,584 in period [2010-2014] to 1:1,086 in period [2015-2020]. Among the 1,337 patients with thyroid ultrasound, 84.29% were SDH whereas 15.71% had TD. Further analysis revealed that more SDH (78.32%) were TCH whereas more TD (87.12%) turned to be PCH. The proportion of blood spot thyrotropin values >5 mIU/L ranged from 8.03 to 20.46%, indicating iodine deficiency. The prevalence of preterm infants increased from 5.50% in period [2010-2014] to 7.06% in period [2015-2020] (p<0.001). CONCLUSIONS: In the past decade, the CH incidence has increased progressively. SDH was the majority of CH, most of which were TCH, while most patients with TD were PCH. The increased incidence might be mainly due to iodine deficiency and increased rates of preterm infants in our study.

Clinical and biochemical characteristics of patients with ornithine transcarbamylase deficiency.

BACKGROUND: Ornithine transcarbamylase deficiency (OTCD) is pleomorphic congenital hyperammonemia, in which the prognosis of the patient is determined both by genotype and environmental factors. This study investigated the clinical and biochemical characteristics of OTCD patients with different prognosis. METHOD: Of 35 OTCD patients, six males deceased at the first disease-onset, 17 males survived and had controllable ammonia levels after treatment, and 12 females survived through the first disease-onset but had intractable hyperammonemia and high mortality. Fasting blood samples from patients collected at three disease stages were used for the analysis of amino acid (AA) profile, acylcarnitine profile, and micronutrients. Differences in profiles between patients and healthy controls and within patient groups were studied. RESULTS: All OTCD patients had accumulation of glutamine, homocitrulline, lysine, glutamate, cystathionine, and pipecolic acid, as well as deficiency of citrulline, tryptophan, threonine, and carnitine. For male non-survivors, most other AAs and long-chain acylcarnitines were elevated at disease onset, of which the levels of creatine, N-acetylaspartic acid, and homoarginine were remarkably high. Male survivors and female patients had most other AAs at low to normal levels. Compared with male survivors, female patients had much lower protein-intolerance, as indicated by significantly lower levels of protein consumption indicators, including essential AAs, 1-methylhistidine, acylcarnitines et al., but high levels of ammonia. Female patients still had significantly higher levels of citrulline, homocitrulline, and citrulline/arginine compared to male survivors. CONCLUSION: Unique profiles were observed in each group of OTCD patients, indicating specific physiological changes that happened to them.

[Complex glycerol kinase deficiency in three children].

Glycerol kinase deficiency (GKD), a rare X-linked recessive disorder, is classified into two types: isolated and complex. Complex GKD is an Xp21 contiguous gene deletion involving the glycerol kinase locus together with the adrenal hypoplasia congenita (AHC) or Duchenne muscular dystrophy (DMD) loci or both. Its clinical features depend on the involved loci. GKD can be confirmed by an elevated urinary glycerol concentration tested by gas chromatography mass spectrometry (GC/MS). The three cases reported here were all male, presenting symptoms from neonatal period. The predominant clinical profile was characterized by hypoadrenocorticism, glyceroluria and Duchenne muscular dystrophy. After receiving a low fat diet and glucocorticoid replacement, they improved with relieved symptoms of hypoadrenocorticism. But they had significant developmental delays and myasthenia. In the follow-up two of them died of adrenal crisis.