Clinical features and genetic analysis of a child with acute form of Tyrosinemia type I due to a novel variant of FAH gene / 中华医学遗传学杂志

OBJECTIVE@#To analyze the clinical phenotype and genetic basis for a child with acute form of tyrosinemia type I (TYRSN1).@*METHODS@#A child with TYRSN1 who presented at the Gansu Provincial Maternal and Child Health Care Hospital in October 2020 was selected as the subject. The child was subjected to tandem mass spectrometry (MS-MS) and urine gas chromatography-mass spectrometry (GC-MS) for the detection of inherited metabolic disorders, in addition with whole exome sequencing (WES). Candidate variants were validated by Sanger sequencing.@*RESULTS@#The child's clinical features included abdominal distension, hepatomegaly, anemia and tendency of bleeding. By mass spectrometry analysis, her serum and urine tyrosine and succinylacetone levels have both exceeded the normal ranges. WES and Sanger sequencing revealed that she has harbored c.1062+5G>A and c.943T>C (p.Cys315Arg) compound heterozygous variants of the FAH gene, which were inherited from her father and mother, respectively. Among these, the c.943T>C was unreported previously.@*CONCLUSION@#Considering her clinical phenotype and result of genetic testing, the child was diagnosed with TYRSN1 (acute type). The compound heterozygous variants of the FAH gene probably underlay the disease in this child. Above finding has further expanded the spectrum of FAH gene variants, and provided a basis for accurate treatment, genetic counseling and prenatal diagnosis for her family.

Analysis of genotypes and phenotypes of three children with Cornelia de Lange syndrome / 中华医学遗传学杂志

OBJECTIVE@#To analyze the clinical phenotype and results of genetic testing in three children with Cornelia de Lange syndrome (CdLS).@*METHODS@#Clinical data of the children and their parents were collected. Peripheral blood samples of the pedigrees were collected for next generation sequencing analysis.@*RESULTS@#The main clinical manifestations of the three children have included growth delay, mental retardation, peculiar facies and other accompanying symptoms. Based on the criteria proposed by the International Diagnostic Consensus, all three children were suspected for CdLS. As revealed by whole exome sequencing, child 1 has harbored NIPBL gene c.5567_5569delGAA insTAT missense variant, child 2 has harbored SMC1A gene c.607A>G missense variant, and child 3 has harbored HDAC8 gene c.628+1G>A splicing variant. All of the variants were de novo in origin.@*CONCLUSION@#All of the children were diagnosed with CdLS due to pathogenic variants of the associated genes, among which the variants of NIPBL and HDAC8 genes were unreported previously. Above finding has enriched the spectrum of pathogenic variants underlying CdLS.

Genetic analysis of a child with Pitt-Hopkins syndrome due to a novel variant of TCF4 gene derived from low percentage maternal mosaicism / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic etiology of a child with Pitt-Hopkins syndrome.@*METHODS@#A child who had presented at the Medical Genetics Center of Gansu Provincial Maternal and Child Health Care Hospital on February 24, 2021 and his parents were selected as the study subjects. Clinical data of the child was collected. Genomic DNA was extracted from peripheral blood samples of the child and his parents and subjected to trio-whole exome sequencing (trio-WES). Candidate variant was verified by Sanger sequencing. Karyotype analysis was also carried out for the child, and her mother was subjected to ultra-deep sequencing and prenatal diagnosis upon her subsequent pregnancy.@*RESULTS@#The clinical manifestations of the proband included facial dysmorphism, Simian crease, and mental retardation. Genetic testing revealed that he has carried a heterozygous c.1762C>T (p.Arg588Cys) variant of the TCF4 gene, for which both parents had a wild-type. The variant was unreported previously and was rated as likely pathogenic based on the guidelines of the American College of Medical Genetics and Genomics (ACMG). Ultra-deep sequencing indicated that the variant has a proportion of 2.63% in the mother, suggesting the presence of low percentage mosaicism. Prenatal diagnosis of amniotic fluid sample suggested that the fetus did not carry the same variant.@*CONCLUSION@#The heterozygous c.1762C>T variant of the TCF4 gene probably underlay the disease in this child and has derived from the low percentage mosaicism in his mother.

Prenatal diagnosis for a fetus with Walker-Warburg syndrome / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic etiology for a fetus with Walker-Warburg syndrome(WWS).@*METHODS@#A fetus with WWS diagnosed at Gansu Provincial Maternity and Child Health Care Hospital in June 9, 2021 was selected as the study subject. Genomic DNA was extracted from amniotic fluid sample of the fetus and peripheral blood samples from its parents. Trio-Whole exome sequencing (trio-WES) was carried out. Candidate variants were verified by Sanger sequencing.@*RESULTS@#The fetus was found to harbor compound heterozygous variants of the POMT2 gene, namely c.471delC (p.F158Lfs*42) and c.1975C>T (p.R659W), which were respectively inherited from its father and mother. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), they were respectively rated as pathogenic (PVS1+PM2_Supporting+PP4) and likely pathogenic (PM2_Supporting+PM3+PP3_Moderate+PP4).@*CONCLUSION@#Trio-WES may be used for the prenatal diagnosis of WWS. The compound heterozygous variants of the POMT2 gene probably underlay the disorder in this fetus. Above finding has expanded the mutational spectrum of the POMT2 gene and enabled definite diagnosis and genetic counseling for the family.

Clinical features, gene analysis and prenatal diagnosis with NDP gene mutation in a family / 中华眼底病杂志

Objective:To observe and determine the gene mutation site and clinical phenotype of a NDP gene mutant family, and provide a basis for the prenatal diagnosis of offspring. Methods:A pedigree investigation study. Two patients and 6 family members of a third-generation Han family with NDP gene mutation who were admitted to the Maternal and Child Health Hospital of Gansu Province from July 2019 to December 2021 were included in the study. The patients and their parents underwent the examination of pupil light reflex, strip light imaging, visual acuity evaluation, fundus color photography, and wide-field fluorescein fundus angiography (FFA). Peripheral blood of all the subjects was collected, the pathogenic genes were screened by whole exome sequencing, and NDP genes were detected by amplification of multiple ligated probes. DNA prenatal diagnosis was performed by amniocentesis at 19th weeks of the mother's third gestation. Results:Proband (Ⅲ1), male, 4 years old, full term natural delivery. At about 40 days after birth, B-mode ultrasonography indicated total retinal detachment in both eyes. Normal hearing and intelligence. Fundus examination was not performed. First sibling of proband (Ⅲ2, big younger brother), ophthalmologic examination 30 days after birth, retinal detachment in both eyes. Proband's mother (Ⅱ2) had unvascularized peripheral temporal retina in both eyes. Wide-angle FFA examination showed no vascularization of the peripheral temporal retina in both eyes, and slight leakage of peripheral vascular fluorescein. The proband's second sibling (Ⅲ3, little younger brother) was screened for neonatal eye disease 1 day after birth. No abnormalities were observed outside both eyes. Cornea and lens transparent. No abnormalities were observed in the optic disc and macula in both eyes. No vascular curvature was observed in the peripheral retina. The results of gene detection showed that there was hemizygote deletion in exon 2 of NDP gene of the proband (Ⅲ1) and its big younger brother (Ⅲ2). His mother (Ⅱ2) had heterozygosity deletion in exon 2 of NDP gene. The phenotype and genetic test results of the proband's father (Ⅱ1), uncle (Ⅱ3), maternal grandfather (Ⅰ1) and maternal grandmother (Ⅰ2) were not abnormal. Conclusions:The hemizygote deletion in exon 2 of NDP gene is a pathogenic variation in the native family. The clinical phenotypes of different genders are different. Prenatal diagnosis is an effective way to block hereditary diseases in families.

Townes-Brocks syndrome caused by de novo mutation in spalt-like transcription factor 1 gene: a case report and literature review / 中华围产医学杂志

Objective:To summarize the clinical features and gene variations in children with Townes-Brocks syndrome (TBS).Methods:The clinical data of a female infant diagnosed with TBS caused by human spalt-like transcription factor 1 ( SALL1) gene mutation in Gansu Maternal and Child Health Hospital in May 2022 were analyzed retrospectively. Relevant articles up to July 2022 were retrieved from several databases including CNKI, VIP, Wanfang, Chinese Medical Journal Network and PubMed with the terms of " SALL1 gene" and "Townes-Brocks syndrome". Patients diagnosed with TBS caused by SALL1 gene mutation were retrieved and the clinical phenotype-genotype correlations in patients with TBS caused by frameshift mutation in SALL1 gene were analyzed and summarized. Descriptive statistical analysis was applied. Results:(1) Clinical data: The index patient was a 40-day-old girl exhibiting major clinical manifestations of polycystic kidney dysplasia, congenital external ear deformity, preaxial polydactyly and recto-perineal fistula. Whole exome sequencing and Sanger sequencing revealed a heterozygous variation of c.420delC (p.S141fs*42) in the SALL1 gene, while the same gene was found to be wild type in her parents and sister. The variant was predicted to be pathogenic (PVS1+PS2+PM2). (2) Literature review retrieved 161 cases of TBS, of which 71 were attributable to a frameshift mutation in SALL1 gene. Clinical phenotypes of the 71 cases and the index case were summarized. TBS was mainly characterized by external ear, hand and anal deformities, sometimes accompanied by hearing loss, abnormal kidney development and foot deformity. A small number of affected cases presented with rare clinical phenotypes such as abnormal eyes, hypothyroidism and abnormal development. At present, the human gene mutation database records 110 variations in the SALL1 gene, with a majority located in exon 2. The most common mutation type was frameshift variation, accounting for 52%, followed by missense variation and nonsense variation. Conclusion:TBS should be considered in children with ear, hand and anal malformations, accompanied by renal dysfunction and hearing loss, and genetic testing is recommended for timely diagnosis.

Genetic analysis of 21 cases of methylmalonic acidemia / 中华医学遗传学杂志

OBJECTIVE@#To carry out genetic analysis for 21 patients with methylmalonic acidemia (MMA) and provide genetic counseling for their families.@*METHODS@#Next generation sequencing (panel) was used to detect the pathogenic variants underlying the disease.@*RESULTS@#In total 29 variant sites of MMUT, MMAA, MMUT were identified in the 21 patients, with common variants including c.323G>A (10%), c.917C>T (10%), c.984delC (10%) of MMUT gene, and c.609G>A (45%), c.80A>G (10%) , c.567dupT (10%) of MMACHC gene. Among these, c.2000A>G of MMUT, c.298G>T of MMACHC and c.734-7A>G of MMAA gene were unreported previously.@*CONCLUSION@#Genetic testing for MMA patients can clarify the cause of the disease and provide a basis for the clinical diagnosis. Discovery of novel variants has enriched the mutational spectrum of MMA.

Gene variation analysis and prenatal diagnosis for 54 families with oculocutaneous albinism / 中华围产医学杂志

Objective:To investigate the pathogenic gene locus and prenatal genetic diagnosis of 54 families with oculocutaneous albinism (OCA).Methods:This retrospective study enrolled 54 OCA probands and their families from Gansu Province Maternal and Child Health Care Hospital from May 2014 to May 2020. TYR gene variation screening was performed on the probands by Sanger sequencing. Those with negative results were analyzed by high-throughput sequencing, and further verification was performed on their parents by Sanger sequencing. Among the 54 families, 15 ml amniotic fluid were collected from 16 women at 18-21 gestational weeks in their subsequent pregnancy. Sanger sequencing combined with short tandem repeats sequence for linkage analysis were performed for genetic analysis. All data were analyzed using descriptive statistical analysis. Results:Out of the 54 OCA probands, 48 were diagnosed as OCA1, five were OCA2 and one was OCA4 based on the Sanger sequencing and high-throughput sequencing detection. A total of 26 different variation sites were involved in the 48 OCA1 probands, including 15 missense mutations, five nonsense mutations, three splicing mutations, and three frame-shift mutations, among which, c.929insC (29%, 28/96) was the most frequent mutation, followed by c.896G>A (11%, 11/96), c.832C>T (8%, 8/96) and c.703T>C (5%, 5/96). The diagnosis was confirmed in all 16 fetuses in the 16 families that underwent prenatal diagnosis. Five of them were affected and their mothers chose to terminate the pregnancies, the other 11 pregnancies continued to delivery, including seven heterozygous carriers and four fetuses without the same pathogenic allele as the proband. Maternal contamination was excluded in all prenatal samples using short tandem repeat for linkage analysis. All 11 children were in good health during telephone follow-up one month after birth. Postnatal validations were consistent with the prenatal tests.Conclusions:Genetic diagnosis could accurately identify various types of OCA and help to provide prenatal diagnosis and fertility consultation for subsequent pregnancies.

Analysis of genetic variant in a child with concomitant spinal muscular atrophy and Citrin protein deficiency / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a child with concomitant spinal muscular atrophy (SMA) and Citrin protein deficiency.@*METHODS@#The child was subjected to whole exome sequencing by using target sequence capture high-throughput sequencing. Candidate variants were verified by Sanger sequencing. The SMN genes of the patient were also analyzed through multiplex ligation-dependent probe amplification (MLPA).@*RESULTS@#The patient was found to carry homozygous deletion of exons 7 and 8 of the SMN1 gene, for which his parents were both carriers. The patient also carried compound heterozygous variants c.1737G>A and IVS16ins3kbof the SLA25A13 gene, in addition with compound heterozygous variants c.948G>A and c.2693T>C of the POLG gene, for which his parents were carriers, too.@*CONCLUSION@#Variants of the SLC25A13 gene probably underlay the deficiency of Citrin protein, which may lead to neonatal intrahepatic cholestasis (NICCD). The patient also had SMA. The compound heterozygous variants c.948G>A and c.2693T>C of the POLG gene are likely to cause mitochondrial DNA deletion syndrome type 4A, though other types of mitochondrial disease cannot be excluded.

Identification of a novel PAX6 mutation in a sporadic case with congenital aniridia / 中华医学遗传学杂志

OBJECTIVE@#To identify mutation of the PAX6 gene in a patient with congenital aniridia.@*METHODS@#DNA was extracted from peripheral blood sample of the patient and analyzed by direct PCR-Sanger sequencing.@*RESULTS@#The proband was found to harbor a heterozygous c.239T>A (p.Ile80Asn) mutation of the PAX6 gene. The same mutation was not found in his parents and 150 healthy controls.@*CONCLUSION@#A novel mutation of the PAX6 gene has been identified in a sporadic case with congenital aniridia.

Clinical and cyto-molecular genetics analysis of trisomy 12p in neonates: a case report / 临床儿科杂志

Objective To explore the clinical features, cytogenetic and molecular genetics characteristics of trisomy 12 p in neonates. Method The clinical data were reviewed in a neonate with trisomy 12 p confirmed by routine G-banding chromosome karyotype analysis, high throughput sequencing chromosome copy number variation analysis (CNV) and lymphocyte interphase fluorescence in situ hybridization (FISH) . Results The chromosome karyotype in peripheral blood of the neonate was 47, XX, +mar, and the karyotypes of her parents were normal. CNV detected a regional duplication of 12 p13.33-p11.1 (160001-34860000) with a fragment size of 34.7 Mb. Peripheral blood lymphocyte interphase FISH showed that there were 3 signals in the short arm of chromosome 12 in all interphase nuclei of the neonate, and no chimera existed. It was finally confirmed to be trisomy 12 p. Conclusion The combination of clinical features, peripheral blood karyotype analysis, CNV and FISH techniques can effectively confirm the diaganosis of trisomy 12 p.

Prenatal diagnosis and PAH gene mutations in 55 pedigrees with phenylketonuria / 中华围产医学杂志

Objective To investigate phenylalanine hydroxylase ( PA H ) gene mutations and to perform prenatal diagnosis in 55 pedigrees with classical phenylketonuria (PKU). Methods Subjects of this study were 55 probands diagnosed with PKU in the Gansu Provincial Maternal and Child Health Care Hospital from 2013 to 2017 and their pedigrees. Sanger sequencing/Multiplex ligation-dependent probe amplification (MLPA) was used to investigate PA H gene mutations in these probands and their parents. Sanger sequencing/MLPA, linkage analysis of three common short tandem repeats (STR) including PAH-26, PAH-STR and PAH-32 in the PA H gene and paternity testing were used in combination for prenatal diagnosis of 60 fetuses in the 55 pedigrees. Results Among the 110 alleles in the 55 probands, 108 mutant alleles (98.2%) were found by Sanger sequencing. The 108 mutant alleles located in 38 regions resulting in 22 missense mutations, nine splice site mutations, five nonsense mutations and two microdeletion. The most common mutations were c.728G>A (22.2%, 24/108), c.442-1G>A (5.6%, 6/108), c.611A>G (5.6%, 6/108), c.764T>C (5.6%, 6/108), c.1068C>A (5.6%, 6/108) and c.331C>T (4.6%, 5/108). Loss of heterozygosity in 4-5 and 4-7 exons were detected by MLPA in two probands, in which only one mutation was unidentified. Prenatal diagnosis for the 60 fetuses were successfully performed. Among them, 17 fetuses (28.3%) were affected, 29 fetuses (48.3%) were heterozygous carriers and fetuses 14(23.4%) were unaffected ones. Conclusions Combination of Sanger sequencing/MLPA, linkage analysis and paternity testing could provide accurate prenatal diagnosis in pedigrees with PKU.

Prenatal diagnosis and mutation analysis of fibroblast growth factor receptor 3 gene in achondroplasia / 中华围产医学杂志

Objective To explore the value of prenatal genetical diagnosis by mutation analysis of achondroplasia (ACH) fibroblast growth factor receptor 3 (FGFR3) gene.Methods Genomic DNA from nine ACH patients and their parents in Gansu Maternal and Child Health Hospital from July,2010 to December,2014 was prepared for polymerase chain reaction.Direct sequencing revealed the samples were performed after amplification of exon 10 of FGFR3 containing the potential mutation.Fetal DNA was extracted from cells in both amniotic fluid and umbilical cord,and then exon 10 of FGFR3 was also tested.Three fetuses with short-limb dysplasia were also included and prenatal diagnosis was offered to them through amniocentesis or cordocentesis.Results Prenatal ultrasonography test showed shorter femoral length,which was less than 2-3 standard deviation of normal reference dysplasia fetal performance for femoral short.Femur length is lower than 2-3 standard deviation minus normal value,and discrepancy in biparietal diameter compared with fetuses at the same gestational age.In the four families with one ACH parent,c.1138G ＞ A heterozygous mutation was detected in all of the four mothers,while two fetuses among them showed c.1138G ＞ A heterozygous mutation mutation and the other two were normal.There were other two fetuses with c.1138G ＞ A heterozygous mutation from other two families,one's father had c.1138G ＞ A heterozygous mutations,but not the mother,the other had c.1138G ＞ A heterozygous mutations in both the mother and father.Among the three families with unaffected parents but each had a de novo c.1138G ＞ A mutation child,no mutation of c.1138G ＞ A genotype was detected in their fetuses,neither in the three fetus with short limb dysplasia.Four fetuses with a c.1138G ＞ A mutation and three with short-limb dysplasia were terminated.The other five fetuses whose genotype was normal were born and healthy with normal phenotype at one-year-old follow-up.Conclusion FGFR3 genetic analysis could provide information for genetic counseling and prenatal diagnosis for ACH parents or parents who had an ACH baby to prevent birth defect.

Analysis on screening results of phenylketonuria among 567 691 neonates in Gansu Province / 国际检验医学杂志

Objective To retrospectively analyze the screening results of phenylketonuria(PKU ) among 567 691 neonates in Gansu Province to understand the prevalence situation of PKU and provide the basic data for preventing and treating PKU in Gansu Province .Methods 567 691 samples of neonatal dried heel blood spots were collected by Gansu Province Newborn Screening Cen‐ter from 2009 to 2014 and the phenylalanine (Phe) level was quantitatively determined by the fluorescence quantification method . The identification was performed by using the urine pterine profile analysis and phenylalanine hydroxylase(PAH) gene mutation de‐tection .Results Among 567 691 neonates ,166 neonates were diagnosed as PKU ,the total detection rate was 1/3 420 ,in which 119 cases (71 .7% ) were classic PKU ,33 cases (19 .9% ) were moderate PKU and 14 cases (8 .4% ) were mild PKU .Conclusion The morbidity rate of PKU in Gansu Province is much higher than the national average incidence level ,which is dominated by classic PKU .Therefore Gansu Province should become the major area of PKU prevention and treatment .

Congenital central hypoventilation syndrome: analysis of PHOX2B gene mutation in a case / 中华医学遗传学杂志

OBJECTIVE To report on the phenotype of an infant with central hypoventilation syndrome (CCHS) and result of PHOX2B gene mutation analysis for the purpose of genetic counseling and prenatal diagnosis. METHODS Clinical data of an infant with CCHS was collected and analyzed. Potential mutation of PHOX2B gene was analyzed by amplified fragment length polymorphism (amp-FLP) and DNA sequencing. RESULTS The patient had typical clinical features of CCHS including frequent hypoventilation during sleeping, hypoxemia and hypercapnia which could be corrected by continuous ventilatory support. She also had repeated bruising and was difficult-to-wean, but without any cardiac, pulmonary, neuromuscular or brainstem lesions. DNA sequencing and amp-FLP of the PHOX2B gene showed that the patient has carried a polyalanine expansion repeat mutation (PARM) in exon 3. A 27 bp duplication was confirmed in the repeat sequence of 20 alanines by cloned and sequenced. This has led to an expansion of the repeat tract to 29 alanines. The genotype was therefore 20/29. CONCLUSION A patient with CCHS has been described. Mutation screening of PHOX2B gene can be used as an important support for diagnosis and genetic counseling for such patients.

The mutation analysis of PAH gene and prenatal diagnosis in classical phenylketonuria family / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To characterize the mutation spectrum of phenylalanine hydroxylase (PAH) gene and perform prenatal diagnosis for families with classical phenylketonuria.</p><p><b>METHODS</b>By stratified sequencing, mutations were detected in the exons and flaking introns of PAH gene of 44 families with classical phenylketonuria. 47 fetuses were diagnosed by combined sequencing with linkage analysis of three common short tandem repeats (STR) (PAH-STR, PAH-26 and PAH-32) in the PAH gene.</p><p><b>RESULTS</b>Thirty-one types of mutations were identified. A total of 84 mutations were identified in 88 alleles (95.45%), in which the most common mutation have been R243Q (21.59%), EX6-96A>G (6.82%), IVS4-1G>A (5.86%) and IVS7+2T>A (5.86%). Most mutations were found in exons 3, 5, 6, 7, 11 and 12. The polymorphism information content (PIC) of these three STR markers was 0.71 (PAH-STR), 0.48 (PAH-26) and 0.40 (PAH-32), respectively. Prenatal diagnosis was performed successfully with the combined method in 47 fetuses of 44 classical phenylketonuria families. Among them, 11 (23.4%) were diagnosed as affected, 24 (51.1%) as carriers, and 12 (25.5%) as unaffected.</p><p><b>CONCLUSION</b>Prenatal diagnosis can be achieved efficiently and accurately by stratified sequencing of PAH gene and linkage analysis of STR for classical phenylketonuria families.</p>

Clinical characteristics and genetic analysis in one case of incontinentia pigmenti / 临床儿科杂志

Objective To explore the clinical manifestations and the deletion mutation in NEMO gene in incontinentia pigmenti. Methods The clinical manifestations of one neonatal infant were analyzed. By long PCR ampliifcation, the deletion mutations in NEMO gene and pseudogene ΔNEMO were detected. Results The clinical manifestations were typical skin lesions. Histopathological examination showed focal edema sponge and gathered or scattered eosinophilic granulocytes. The deletion of exons 4-10 in both NEMO andΔNEMO genes were detected in the patient. Conclusions Incontinentia pigmenti is a rare X chromosome linked dominant genetic disease. It has typical clinical manifestations and pathological changes, and deletion mutation in NEMO gene.