Clinical investigation and mutation analysis of a child with citrin deficiency complicated with purpura, convulsive seizures and methioninemia / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To analyze the clinical features and SLC25A13 gene mutations of a child with citrin deficiency complicated with purpura, convulsive seizures and methioninemia.</p><p><b>METHODS</b>The patient was subjected to physical examination and routine laboratory tests. Blood amino acids and acylcarnitines, and urine organic acids and galactose were analyzed respectively with tandem mass spectrometry and gas chromatographic mass spectrometry. SLC25A13 gene mutation screening was conducted by high resolution melt (HRM) analysis.</p><p><b>RESULTS</b>The petechiae on the patient's face and platelet count (27×10(9)/L, reference range 100×10(9)/L-300×10(9)/L) supported the diagnosis of immunologic thrombocytopenic purpura (ITP). Laboratory tests found that the patient have abnormal coagulation, cardiac enzyme, liver function and liver enzymes dysfunction. Tandem mass spectrometry also found methionine to be increased (286 μmol/L, reference ranges 8-35 μmol/L). The patient did not manifest any galactosemia, citrullinemia and tyrosinemia. Analysis of SLC25A13 gene mutation found that the patient has carried IVS16ins3kb, in addition with abnormal HRM result for exon 6. Direct sequencing of exon 6 revealed a novel mutation c.495delA. The same mutation was not detected in 100 unrelated healthy controls. Further analysis of her family has confirmed that the c.495delA mutation has derived from her farther, and that the IVS16ins3kb was derived from her mother.</p><p><b>CONCLUSION</b>The clinical features and metabolic spectrum of citrin deficiency can be variable. The poor prognosis and severity of clinical symptoms of the patient may be attributed to the novel c.495delA mutation.</p>

Utilization of high-resolution melting analysis to screen patients with neonatal intrahepatic cholestasis caused by citrin deficiency / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To assess the feasibility of high-resolution melting (HRM) analysis for screening patients with neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD).</p><p><b>METHODS</b>Based on previous studies on SLC25A13 gene in Chinese patients with NICCD, four hotspot mutations (851del4, 1638ins23, IVS6+5G>A and IVS16ins3kb) were selected. Results of the HRM analysis was validated using 50 negative controls and 20 patients with NICCD whose genotypes were confirmed previously by direct sequencing. With the established protocol, 171 suspected patients were enrolled. Samples with abnormal melting curves were further validated by DNA sequencing.</p><p><b>RESULTS</b>HRM analysis can accurately determine the genotypes of all negative controls and patients. The sensitivity and specificity of the technique reached 100% (70/70). The melting curves of samples with the same genotype were highly reproducible. In 171 suspected patients, seven NICCD patients were detected by HRM. Identified mutations have included one case of 851del4 homozygote, one case of IVS6+5G>A heterozygote, 3 cases of 851del4 heterozygotes, one case of [IVS6+5G>A]+[ 851del4] and one case of [1638ins23+IVS16ins3kb]+[1638ins23]. All mutations were subsequently confirmed by DNA sequencing.</p><p><b>CONCLUSION</b>HRM analysis is a convenient, high-throughput and rapid technique for the screening of NICCD patients.</p>

Analysis of clinical features and GCDH gene mutations in four patients with glutaric academia type I / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To review clinical features of four male patients with glutaric academia type I and screen glutaryl-CoA dehydrogenase (GCDH) gene mutations.</p><p><b>METHODS</b>The 4 patients underwent brain computer tomography (CT) and magnetic resonance imaging (MRI) analyses. Blood acylcarnitine and urine organic acid were analyzed with tandem mass spectrometry and gas chromatographic mass spectrometry. Genomic DNA was extracted from peripheral blood samples. The 11 exons and flanking sequences of GCDH gene were amplified with PCR and subjected to direct DNA sequencing.</p><p><b>RESULTS</b>All patients have manifested macrocephaly, with head circumference measured 50 cm (14 months), 47 cm (9 months), 46 cm (5 months) and 51 cm (14 months), respectively. Imaging analyses also revealed dilation of Sylvian fissure and lateral ventricles, frontotemporal atrophy, subarachnoid space enlargement and cerebellar vermis abnormalities. All patients had elevated glutarylcarnitine (5.8 umol/L, 7.5 umol/L, 8.3 umol/L and 7.9 umol/L, respectively) and high urinary excretion of glutaric acid. Seven mutations were identified among the patients, among which c.146_149del4, IVS6-4_Ex7+4del8, c.508A>G (p.K170E), c.797T>C (p.M266T) and c.420del10 were first discovered.</p><p><b>CONCLUSION</b>Macrocephaly and neurological impairment are the most prominent features of glutaric academia type I. Blood tandem mass spectrometry and urine gas chromatographic mass spectrometry analysis can facilitate the diagnosis. The results can be confirmed by analysis of GCDH gene mutations.</p>

SLC25A13 gene analysis in neonates with intrahepatic cholestasis caused by citrin deficiency / 中国当代儿科杂志

<p><b>OBJECTIVE</b>Neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) which resulted from mutation in SLC25A13 gene can present transient intrahepatic cholestasis, low birth weight, growth retardation, hypoproteinemia and so on. This study aimed to identify the mutation type of NICCD patients by DNA sequencing.</p><p><b>METHODS</b>Twenty children diagnosed as NICCD were consented to enroll in this study. PCR assays were performed to amplify the eighteen exons and its flanking sequences of SLC25A13 gene, which were defined as the upstream and downstream 50 bp from starting and ending site of the exons. Then the PCR products were purified and followed by automated DNA sequencing. The IVS16ins3kb mutation was detected by nested PCR and RT-PCR.</p><p><b>RESULTS</b>Seven genetic variations of SLC25A13, termed as 851del4, 1638ins23, IVS16ins3kb, IVS6+5G>A, c.775C>T (p.Q259X), c.1505C>T (p.P502L) and c.1311C>T (p.C437C), were identified in the subjects, of which c.775C>T (p.Q259X), c.1505C>T (p.P502L) and c.1311C>T (p.C437C) were reported for the first time in NICCD patients. And a compound mutation of［1638ins23+IVS16ins3kb］was also identified. In 20 patients with NICCD, 6 patients were 851del4 homozygotes, 7 patients were compound heterozygotes, and 7 patients were heterozygotes of single mutation. 851del4 was the major mutation type (64%), followed by 1638ins23 (15%), IVS16ins3kb (12%) and IVS6+5G>A (6%).</p><p><b>CONCLUSIONS</b>851del4 is the major mutation type in Chinese patients with NICCD.</p>

Analysis of clinical features and gene mutations in two Chinese pedigrees with late-onset methylmalonic acidemia, cblC type / 中华儿科杂志

<p><b>OBJECTIVE</b>CblC is the most common type of methylmalonic acidemia with homocysteinemia. MMACHC is the coding gene. This study aimed at understanding clinical features and gene mutations in 2 Chinese pedigrees who had late-onset methylmalonic acidemia complicated with homocysteinemia.</p><p><b>METHOD</b>The clinical data of 2 cases were analyzed. The MMACHC gene mutation was detected using polymerase chain reaction (PCR) and DNA sequencing.</p><p><b>RESULT</b>The age of onset was 13 years and 12 years, respectively. They both presented with nervous system symptoms. The main clinical features were developmental retardation and degradation, including motion, speech and intelligence. One patient complained of anemia. The other patient was misdiagnosed as having a viral encephalitis. Both patients showed remarkable elevation of methylmalonic acid and homocysteine levels in urine. Both had received therapy with vitamin B(12). The symptoms were rapidly relieved. The follow-up till now showed apparent improvement in the 2 cases. Three mutations in the MMACHC gene were found in the two Chinese pedigrees. Both patients were compound heterozygotes of two mutant alleles: one patient had a G-to-A transition at nucleotide 482 (G482A) that caused an arginine-to-glutamine substitution at position 161 of the protein (R161Q), and a deletion of AAG at nucleotide 658_660 (658_660delAAG) which resulted in lysine deleting at position 220 of the protein (K220del); the other patient had a G482A and a G-to-A transition at nucleotide 609 (G609A) that caused a tryptophan-to-termination codon substitution at position 203 of the protein (W203X). Otherwise, the authors also detected parents of two families. Each had a heterozygote of one mutation.</p><p><b>CONCLUSION</b>Late-onset methylmalonic acidemia patients had a variety of clinical manifestation, the first symptom was mainly abnormality of nervous system. One case was accompanied with hematological abnormalities. Two patients were vitamin B(12) responsive. In this study, the mutations were all detected on the fourth exon, the G482A mutation was probably associated with late-onset cases.</p>