Prenatal to preimplantation genetic diagnosis of a novel compound heterozygous mutation in HSPA9 associated with Even-Plus syndrome.

BACKGROUND: Heat shock protein family A member 9 (HSPA9) prevents unfolded and dysfunctional protein accumulation, with genetic variants known to be pathogenic. Here, we determined the genetic cause of Even-Plus syndrome (OMIM: 616854) in a Chinese family. METHODS: We collected samples from two affected and two normal individuals. Whole-exome sequencing was performed to identify their genetic profiles. Potential variants were validated using Sanger sequencing. Assisted reproduction with mutation-free embryos successfully blocked the transmission of mutations. RESULTS: We identified novel inherited pathogenic complex heterozygous variations in the HSPA9 gene in the two affected fetuses. Three-dimensional spatial simulation of the HSPA9 protein after prediction of the mutated RNA splicing pattern abolished part of the substrate-binding domain of the protein. According to ACMG guidelines, c. 1822-1G>A and c. 1411-3T>G were classified as pathogenic and likely pathogenic, respectively. Mutation-free embryos were selected for transplantation and reconfirmed to possess no mutations. A healthy daughter was successfully born into the family. CONCLUSIONS: This study is the first to report complex heterozygous variations in the HSPA9 gene that influence alternative splicing in early pregnancy. Our findings expand on the mutational spectrum leading to Even-Plus syndrome and provide a basis for genetic counseling and future embryonic studies.

Novel compound heterozygous mutations in TELO2 in an infant with You-Hoover-Fong syndrome: A case report and literature review.

We report here the clinical diagnosis and treatment and genetic mutations of an infant with You-Hoover-Fong syndrome (YHFS). The relevant literature review was conducted. A female infant aged 17 months was admitted to Nanhai Affiliated Maternity and Children's Hospital of Guangzhou University of Chinese Medicine due to "global development delay complicated with postnatal growth retardation for more than 1 year." The infant was diagnosed with YHFS due to the onset of extremely severe mental retardation, microcephaly, abnormal hearing, severe protein-energy malnutrition, congenital cataract, cleft palate (I°), congenital atrial septal defect, brain atrophy, hydrocephalus, and brain hypoplasia. The whole exon sequencing revealed two compound heterozygous mutations, including a likely pathogenic TELO2 variant, c.2245A > T (p.K749X) from her mother and an uncertain variant, c.2299C > T (p.R767C) from her father, validated by Sanger sequencing. After bilateral cataract surgery, the infant obtained better visual acuity and showed more responses and interactions with her parents. Diagnosis and treatment of this case prompt that these TELO2 variants have not been reported, deepening the understanding of the molecular and genetic mechanism of YHFS in clinical practice.

Delayed progressive sensorineural hearing loss due to a novel compound heterozygous PTPRQ mutation in a Chinese patient.

BACKGROUND: The Protein tyrosine phosphatase receptor Q (PTPRQ) gene encodes a member of the type III receptor-like protein tyrosine phosphatase family found in the stereocilium. Mutations in PTPRQ are mostly associated with deafness, autosomal recessive type 84 (DFNB 84), which usually results in progressive familial hearing loss. METHODS: A 25-year-old woman and her sister, both with postlingual-delayed progressive sensorineural hearing loss, were examined. They were from a nonconsanguineous marriage and had no family history of hearing loss. New compound heterozygous PTPRQ gene mutations, nonsense (c.90C > A, p.Y30X) and splice (c.5426 + 1G > A) mutations in two PTPRQ alleles, were identified in the two sisters and were presumably autosomal recessive. The c.90C > A (p.Y30X) mutation was mapped to exon 2 of PTPRQ (NM_001145026). RESULTS: The c.90C > A mutation leads to a premature stop codon and a truncated protein. The c.5426 + 1G > A mutation leads to a truncated protein lacking the extracellular domain. Hence, both mutations were predicted to be pathogenic, leading to a deficiency of the extracellular, transmembrane, and phosphatase domains because of nonsense-mediated mRNA degradation. CONCLUSIONS: This study increases the spectrum of PTPRQ gene mutations that might be involved in delayed progressive autosomal recessive non-syndromic hearing loss.

A novel compound heterozygous mutation of COL6A3 in Chinese patients with isolated cervical dystonia.

Background: The etiology and pathogenesis of idiopathic dystonia remain obscure. Recent studies revealed that compound heterozygous mutations in collagen type VI alpha-3 gene COL6A3 may cause recessive isolated dystonia (DYT)-27. However, whether COL6A3 mutations are associated with Chinese patients with isolated dystonia is not yet reported. Methods: In this study, 45 Chinese patients with isolated cervical dystonia were recruited, and their blood DNA samples were subjected to whole-exome sequencing. The potential causal variants of COL6A3 were identified based on the criteria of the American College of Medical Genetics and Genomics and by prediction software. Results: Among 45 isolated cervical dystonia patients, 18 patients (10 female patients and eight male patients) were found to have seven potential causal variants in the COL6A3 gene. Among these variants, a compound heterozygous mutation was found in one patient. One allele had a c.1264G>A mutation in exon 4 that resulted in an amino acid substitution of methionine for valine at codon 422 (p.Val422Met) and the other a c.8965+9G>A mutation involving a splicing change in exon 40. In addition, other five missense variants, including c.958G>A (p.Ala320Thr), c.1478T>C (p.Val493Ala), c.1597C>T (p.Arg533Cys), c.1762G>A (p.Asp588Asn), and c.4912G>A (p.Ala1638Thr), were identified as well. Conclusion: We identified a novel deleterious compound heterozygous mutation as well as five missense variants in the COL6A3 gene of Chinese patients with cervical dystonia. These findings may expand the spectrum of the COL6A3 genotype in isolated dystonia.

A novel compound heterozygous mutation in TUBB8 causing early embryonic developmental arrest.

PURPOSE: Mutations in the ß-tubulin isotype, TUBB8, can cause female infertility. Although several mutations of TUBB8 have been reported, the full spectrum for guiding genetics counseling still needs to be further explored. Here, we sought to identify novel variants in TUBB8 and their phenotypic effects on microtubule network structure in vitro. METHODS: Whole-exome sequence analysis was performed in two families with infertility to detect pathogenic variants, with validation by Sanger sequencing. All gene variants and protein structures were predicted in silico. Cells were transfected with wild-type and mutants, and immunofluorescence analysis was performed to visualize microtubule network changes. RESULTS: We detected a novel compound heterozygous mutation, c.915_916delCC (p.Arg306Serfs*21) and c.82C > T (p.His28Tyr), and a benign heterozygous variant c.1286C > T (p.Thr429Met) in TUBB8 in the two families. Female patients with p.Arg306Serfs*21 and p.His28Tyr were infertile with early embryonic developmental arrest. The female patient with p.Thr429Met gave birth to a healthy baby in the second in vitro fertilization frozen embryo transfer cycle. The p.Arg306Serfs*21 mutation was predicted to cause large structural alteration in the TUBB8 protein and was confirmed to produce a truncated and trace protein by western blot analysis. Immunofluorescence analysis of transfected HeLa cells showed that p.Arg306Serfs*21 significantly disrupted microtubule structure. CONCLUSIONS: Our findings expand the known mutational spectrum of TUBB8 associated with early embryonic developmental arrest and female infertility.

Mild hyperphenylalaninemia (hpa) presenting as orthostatic tremor: a case report.

BACKGROUND: Orthostatic tremor (OT) is a type of postural tremor of the lower extremities that has not been described in either phenylketonuria (PKU) or hyperphenylalaninemia (HPA). Because little is known about the clinical features and therapeutic responses of OT in mild HPA, we describe a mild HPA patient who presented with OT as an initial symptom. CASE PRESENTATION: A 22-year-old male was admitted for bilateral leg tremor while standing, with symptom onset eight months prior. One month before admission, the tremor disappeared in the left leg but persisted in the right leg. Electromyography recorded from the right gastrocnemius revealed a 6-8 Hz tremor, which appeared when the patient was standing and disappeared when he was resting or walking. Blood screening showed a phenylalanine/tyrosine ratio of 2.06 and a phenylalanine level of 140 µmol/L. Urine metabolic screening was negative. Whole-exome sequencing confirmed the presence of a compound heterozygous mutation, c.158G > A and c.728G > A, in phenylalanine hydroxylase (PAH) gene. After three months of levodopa/benserazide tablets (250 mg, tid) and a low-phenylalanine diet treatment, the tremor disappeared. CONCLUSIONS: Young-onset mild HPA is a relatively rare autosomal recessive metabolic disease, and slow OT is a rare clinical feature. Metabolic screening and genetic testing are the keys to early diagnosis and treatment. For adolescents and young adults, appropriate medication and long-term dietary therapy remain important treatments. This case expanded the disease spectrum of slow OT.

Novel Compound Heterozygous Variations in MPDZ Gene Caused Isolated Bilateral Macular Coloboma in a Chinese Family.

Macular coloboma (MC) is a rare congenital retinochoroidal defect characterized by lesions of different sizes in the macular region. The pathological mechanism underlying congenital MC is unknown. Novel compound heterozygous variations, c.4301delA (p.Asp1434fs*3) and c.5255C>G (p.Ser1752Ter), in the multiple PDZ domain (MPDZ) proteins were identified via whole-exome analysis on the proband with isolated bilateral macular coloboma in a Chinese family. Segregation analysis revealed that each of the unaffected parents was heterozygous for one of the two variants. The results of the in silico and bioinformatics analysis were aligned with the experimental data. The knockdown of MPDZ in zebrafish caused a decrease in the ellipsoid zone, a destruction of the outer limiting membrane, and the subsequent RPE degeneration. Overall, the loss of MPDZ in zebrafish contributed to retinal development failure. These results indicate that MPDZ plays an essential role in the occurrence and maintenance of the macula, and the novel compound heterozygous variations were responsible for an autosomal recessive macular deficiency in this Chinese family.

A rare compound heterozygous EIF2AK4 mutation in pulmonary veno-occlusive disease.

BACKGROUND: Pulmonary veno-occlusive disease (PVOD) is a rare, progressive, and oft-fatal condition of pulmonary arterial hypertension that is typically difficult to diagnose and treat. However, with the development of next-generation sequencing technology, an increasing number of patients with PVOD are being diagnosed. METHODS: Initially, we used whole exome sequencing (WES) to identify the proband as a rare compound heterozygous mutation of EIF2AK4 in PVOD. Subsequently, the parents of patient underwent EIF2AK4 screening by Sanger sequencing. RESULTS: In this study, we describe the family tree of a patient with PVOD with a rare compound heterozygous EIF2AK4 mutation. Moreover, we identified a new EIF2AK4 mutation, c.2236_2237insAAGTCCTTCT, in exon 12 of the proband and his mother. This frameshift mutation led to premature termination of the coding protein sequence and widespread loss of protein function, which promoted the development of PVOD. CONCLUSIONS: Our results expand our understanding of the EIF2AK4 mutation spectrum in patients with PVOD, as well as highlight the clinical applicability of WES.

Compound heterozygosity for a variably penetrant variant and a variant of unknown significance in FLT4 causes fully penetrant Milroy's lymphedema.

Milroy disease, known as primary congenital lymphedema, is characterized by chronic tissue swelling due to impaired lymphatic drainage and is inherited in an autosomal dominant manner. This study reports a rare case of Milroy disease affecting siblings from unaffected parents. A one-month-old female infant presented with swelling of the bilateral calf and the dorsum of the feet which had been present since birth. Her 14-month-old brother had a similar presentation since birth with swelling of the bilateral calf and the dorsum of the feet. Milroy disease was diagnosed based on the clinical findings of bilateral lower limb swelling and confirmed by molecular genetic testing. The patient and her family, including her brother, parents, and maternal grandfather, were genetically tested, and two novel missense mutations (NM_182925.4: c.2534T>C; p.Leu845Pro, c.4006G>A; p.Glu1336Lys) were found in the Fms-related tyrosine kinase (FLT4) gene. Mutations segregated by the parents who carried each mutation in the heterozygous state were identified in the patient and her brother. The present case report in which Milroy disease developed in all offspring of parents with a normal phenotype suggests the possibility of a compound heterozygous mutation or non-penetrance during the process of inheritance of Milroy disease.

Cohen syndrome in two patients from China.

BACKGROUND: Cohen syndrome (CS; OMIM 216550) is a rare syndrome with evident clinical heterogeneity. The diverse phenotype comprises early-onset hypotonia and developmental delays, intellectual disabilities, microcephaly, hypermobile joints, neutropenia, myopia, and characteristic facial features. The disease is rarely reported. Vacuolar Protein Sorting 13 Homolog B (VPS13B; OMIM 607817) is the only causative gene of CS. METHODS: Blood samples sourced from both siblings and parents were sent to identify mutations by trio-WES, and changes in the patient's condition were understood through consultation data and follow-up. RESULTS: We reported two siblings affected by developmental delay, microcephaly, intellectual disability, and facial features. The siblings' WES detected compound heterozygous variants in the exon region of VPS13B (NM_017890): c.9337A>T and c.8551A>C. CONCLUSION: Two individuals were diagnosed with CS by genetic testing and clinical features. In addition, we conduct a brief review of the reports on the Chinese population with CS and reinforce the understanding of the correlation between genotype-phenotype.

Correlation between novel compound heterozygous ADAMTSL4 variants and primary phenotypes of ectopia lentis et pupillae.

PURPOSE: To investigate molecular pathogenesis of congenital ectopia lentis accompanied by various ophthalmic manifestations in a pedigree. METHODS: Three female siblings, their spouse and offspring underwent ophthalmic and general medical examinations. Genetic variants were screened with the whole exome sequencing and analyzed in either a dominant or recessive inheritance manner. Gene mutations were ascertained with the Sanger sequencing after the polymerase chain reaction. RESULTS: All three female siblings were diagnosed as the Ectopia lentis et pupillae (ELeP) through combination of clinical examination and genetic analysis. No characteristic pathological changes of skeletal, metabolic and cardiac abnormalities were observed. Thirteen genetic variants were selected out through analyzing in the dominant or recessive inheritance manner, but they were not associated with EL. Among them, ALOX15B variant may explain the skin disease in this pedigree. After inspection the known genes related to EL, novel compound heterozygous mutations (p.Ser264LeufsX37/p.Gly757ValfsX62) in ADAMTSL4 were discreetly identified in this ELeP pedigree. CONCLUSIONS: Novel compound heterozygous ADAMTSL4 variants are responsible for ELeP in the current pedigree. Correlation between ADAMTSL4 variants and ELeP was firstly established based on our 12 years follow-up studies and previous reports of ELeP and of ADAMTSL4-related eye disorders. The primary phenotypes caused by ADAMTSL4 variants include EL, EP, poor pupillary dilation, and axial elongation. Highly varying phenotypes including glaucoma, high myopia retinapathy, and poor vision and so on may be the secondary impairments. All these secondary impairments may be improved if proper clinical interventions are implemented in time.

Targeted Next-Generation Sequencing Identified Novel Compound Heterozygous Variants in the PTPRQ Gene Causing Autosomal Recessive Hearing Loss in a Chinese Family.

Hearing loss is among the most common congenital sensory impairments. Genetic causes account for more than 50% of the cases of congenital hearing loss. The PTPRQ gene, encoding protein tyrosine phosphatase receptor Q, plays an important role in maintaining the stereocilia structure and function of hair cells. Mutations in the PTPRQ gene have been reported to cause hereditary sensorineural hearing loss. By using next-generation sequencing and Sanger sequencing, we identified a novel compound heterozygous mutation (c.997 G > A and c.6603-3 T > G) of the PTPRQ gene in a Chinese consanguineous family. This is the first report linking these two mutations to recessive hereditary sensorineural hearing loss. These findings contribute to the understanding of the relationship between genotype and hearing phenotype of PTPRQ-related hearing loss, which may be helpful to clinical management and genetic counseling.

Case report: biotin-thiamine-responsive basal ganglia disease with severe subdural hematoma on magnetic resonance imaging.

Background: Biotin-thiamine-responsive basal ganglia disease (BTBGD) is a rare, treatable autosomal recessive neurometabolic disorder. This condition eventually leads to severe disability and death if not treated correctly. The clinical features of BTBGD, especially those with unusual complications, are not widely known by neurologists or pediatricians.Case presentation: A 4-month-old male infant was admitted to the hospital with a history of cough for the past 7 days and convulsions of 6 h duration. Physical examination showed confusion, bilateral pupillary light reflex delays, hypertonia of limbs, and brisk tendon reflexes of the limbs. Brain magnetic resonance imaging (MRI) showed multiple abnormal signals in the bilateral basal ganglia, lobes, corpus callosum, brainstem, and brain atrophy. However, his condition continued to worsen. Computed tomography performed 3 months later showed severe subdural hematoma and effusion. Subsequently, he underwent puncture drainage; however, his condition did not improve postoperatively. Repeated MRIs showed increasing subdural hematoma and effusion, and brain atrophy. The patient was diagnosed with BTBGD following whole-genome sequencing, which identified a novel compound heterozygous mutation of SLC19A3 gene. He was treated with biotin and thiamine, and the symptoms gradually improved. Subsequent MRIs showed a decrease in the subdural hematoma and effusion and partial improvement in brain atrophy.Conclusion: To the best of our knowledge, this is the first reported case of BTBGD, complicated by severe subdural hematoma. These observations extend our understanding of the clinical features, neuroimaging spectrum, and gene mutation spectrum of BTBGD. The phenotypic spectrum and pathophysiology of BTBGD are not completely understood and need to be studied further.

A Novel Mutation of Transferrin Receptor 2 in a Chinese Pedigree With Type 3 Hemochromatosis: A Case Report.

Type 3 hereditary hemochromatosis (HH) is a rare form of HH characterized by genetic mutation in the TFR2 gene. Clinical features reported in patients with type 3 HH include abnormal liver function, liver fibrosis, cirrhosis, diabetes, hypogonadism, cardiomyopathy, and skin pigmentation. Since its original description in 2000, 33 pathogenic TFR2 mutations associated with HH have been described until now. Here, we first reported a Chinese pedigree of TFR2-related hemochromatosis with a novel compound heterozygous mutation c.1288G > A (p.G430R)/c.960T > A (p.Y320X). Interestingly, different phenotypes were reported although the proband and his sister shared the same gene mutation. This inconsistency between genotypes and phenotypes indicates multifactorial etiology contributing to the development of HH. Our report broadens the mutation spectrum of the TFR2 gene associated with HH.

Novel compound heterozygous variants in the PCCB gene causing adult-onset propionic acidemia presenting with neuropsychiatric symptoms: a case report and literature review.

BACKGROUND: Propionic acidemia (PA) is a rare autosomal recessive disorder of metabolism caused by mutations in the PCCA or PCCB gene, leading to propionyl CoA carboxylase (PCC) enzyme deficiencies. Most PA patients present variable clinical phenotypes and severity in the neonatal or infant period, with only a few developing symptoms after infancy. This report describes a PA patient with an adult-onset phenotype and a novel compound heterozygous mutation in the PCCB gene. To further explore the genotype-phenotype correlations in late-onset PA, we performed a literature review focusing on and summarizing 11 patients with PCC gene mutations who had the first onset and/or the definite diagnosis after infancy. CASE PRESENTATION: A 21-year-old PA patient presented with weakness of four limbs, gait abnormalities, two episodes of seizures, mental and behavior disorders after severe vomiting. Magnetic Resonance Imaging (MRI) demonstrated sustained bilateral caudate head and putamen symmetrical hyperintensity. Biochemical investigations revealed plasma amino and urine values correlating with a PA profile. Genetic analysis confirmed novel compound heterozygous variants in PCCB, with a newly-found pathogenic mutation (c.467T>C) and the c.1316A>G mutation associated with pathogenicity. CONCLUSION: We identified a novel compound heterozygous mutation in the PCCB gene causing late-onset PA. Patients carrying mutations in the PCCB gene tend to develop late-onset PA and present neuropsychiatric symptoms and/or signs. Further molecular biological research is needed to explore the genotype-phenotype correlations of PA.

A case of adult-onset Wolfram syndrome with compound heterozygous mutations of the WFS1 gene.

PURPOSE: Wolfram syndrome is a rare genetic disorder characterized by juvenile onset of diabetes mellitus with bilateral optic atrophy. We report a case of adult onset Wolfram syndrome with diabetes mellitus at age 22 and optic atrophy after age 40. The WFS1 gene sequence was analyzed in the patient and her father. OBSERVATIONS: A 46-year-old woman presented with bilateral vision loss. She had developed diabetes mellitus at age 22 and underwent bilateral cataract surgery at age 37. Visual acuity was 20/50 in the right eye and 20/200 in the left eye. The pupillary light reflex was sluggish in both eyes. Fundus examination showed bilateral optic atrophy, but there was no diabetic retinopathy. Cecocentral scotoma of both eyes was observed in Goldmann perimetry. There were no intracranial lesions on magnetic resonance imaging. Audiometry demonstrated high-frequency sensorineural hearing loss. Sequence analysis of the WFS1 gene revealed compound heterozygous mutation: c.908T>C p.L303P and c.1232_1233del, p.S411Cfs*131 in the patient and heterozygous mutation c. 908 T>C, p. L303P in her father. CONCLUSIONS AND IMPORTANCE: The patient was diagnosed with adult-onset Wolfram syndrome with compound heterozygous mutations of the WFS1 alleles. Wolfram syndrome must be ruled out even in adult-onset diabetic patients with optic atrophy.

Autosomal recessive spinocerebellar ataxia type 4 with a VPS13D mutation: A case report.

BACKGROUND: Autosomal recessive spinocerebellar ataxia type 4 (SCAR4) is a type of SCA that is a group of hereditary diseases characterized by gait ataxia. The main clinical features of SCAR4 are progressive cerebellar ataxia, pyramidal signs, neuropathy, and macrosaccadic intrusions. To date, many gene dysfunctions have been reported to be associated with SCAR4. CASE SUMMARY: Here, we report a novel compound heterozygous mutation, c.3288delA (p.Asp1097ThrfsTer6), in the VPS13D gene in a young female Chinese patient. The patient found something wrong with her legs about 10 years ago and presented with the typical characteristics of SCAR4 when she came to the hospital, including ataxia, neuropathy, and positive pyramidal signs. She was then diagnosed with SCAR4 and went home with symptomatic schemes. CONCLUSION: SCAR4 is a hereditary disease characterized by ataxia, pyramidal signs, neuropathy, and macrosaccadic intrusions. We report a novel compound heterozygous mutation, c.3288delA (p.Asp1097ThrfsTer6), in the VPS13D gene, which enriches the gene mutation spectrum and provides additional information about SCAR4.

A novel compound heterozygous mutation in GALC associated with adult-onset Krabbe disease: case report and literature review.

Krabbe disease (KD) is a rare autosomal recessive lipid storage leukodystrophy. It is caused by deficient enzyme activity resulting from mutations of the ß-galactocerebrosidase (GALC) gene. KD is distinguished into subtypes based on the age of onset; these are early infantile, late infantile, juvenile, and adult-onset. We report a case of a 47-year-old Caucasian man with a 2-year history of muscle atrophy and weakness in both hands associated with pyramidal signs and mild spasticity in the lower limbs. An extensive work-up led this motor neuron disease-like disorder to be diagnosed as adult-onset KD. The patient was found to be compound heterozygous for two GALC mutations (p.G286D and p.Y490N). These two rare missense mutations have previously been reported with other heterozygous mutations. However, their co-occurrence in a KD patient is novel. From the perspective of this case, we review the current literature on compound heterozygous mutations in adult-onset KD and their phenotypic variability.

Recessive Mutations in ACP4 Cause Amelogenesis Imperfecta.

Amelogenesis imperfecta (AI) is an innate disorder that affects the formation and mineralization of the tooth enamel. When diagnosed with AI, one's teeth can be hypoplastic (thin enamel), hypomature (normal enamel thickness but discolored and softer than normal enamel), hypocalcified (normal enamel thickness but extremely weak), or mixed conditions of the above. Numerous studies have revealed the genes that are involved in causing AI. Recently, ACP4 (acid phosphatase 4) was newly found as a gene causing hypoplastic AI, and it was suggested that mutant forms of ACP4 might affect access to the catalytic core or the ability to form a homodimer. In this study, a Korean and a Turkish family with hypoplastic AI were recruited, and their exome sequences were analyzed. Biallelic mutations were revealed in ACP4: paternal (NM_033068: c.419C>T, p.(Pro140Leu)) and maternal (c.262C>A, p.(Arg88Ser)) mutations in family 1 and a paternal (c.713C>T, p.(Ser238Leu)) mutation and de novo (c.350A>G, p.(Gln117Arg)) mutation in the maternal allele in family 2. Mutations were analyzed by cloning, mutagenesis, immunofluorescence, immunoprecipitation, and acid phosphatase activity test. Comparison between the wild-type and mutant ACP4s showed a decreased amount of protein expression from the mutant forms, a decreased ability to form a homodimer, and a decreased acid phosphatase activity level. We believe that these findings will not only expand the mutational spectrum of ACP4 but also increase our understanding of the mechanism of ACP4 function during normal and pathologic amelogenesis.

Novel LG1 Mutations in Agrin Causing Congenital Myasthenia Syndrome.

The patient had suffered from both proximal and distal limb weakness since her early childhood, without the involvement of ocular or respiratory muscles. Repetitive nerve stimulation (RNS) at 3 Hz showed significant decrement in the area and amplitude of the compound muscle action potential (CMAP) on the right abductor digiti minimi (26%) and trapezius (17%). Whole-exon sequencing revealed two novel heterozygous mutations (p.Q1406Rfs*29 and p.R1521H) in the LG1 domain of agrin, which were deemed likely pathogenic for congenital myasthenic syndromes (CMS) according to a bioinformatics analysis. The patient showed remarkable improvement after treatment with salbutamol. This case expanded the mutation spectrum of AGRN.