Missense mutation in DYNC1H1 gene caused psychomotor developmental delay and muscle weakness: A case report.

BACKGROUND: The DYNC1H1 gene encodes a part of the dynamic protein, and the protein mutations may further affect the growth and development of neurons, resulting in degeneration of anterior horn cells of the spinal cord, and a variety of clinical phenotypes finally resulting in axonal Charcot-Marie-Tooth disease type 20 (CMT20), mental retardation 13 (MRD13) and spinal muscular atrophy with lower extremity predominant 1 (SMA-LED). The incidence of the disease is low, and it is difficult to diagnose, especially in children. Here, we report a case of DYNC1H1 gene mutation and review the related literature to improve the pediatrician's understanding of DYNC1H1 gene-related disease to make an early correct diagnosis and provide better services for children. CASE SUMMARY: A 4-mo-old Chinese female child with adducted thumbs, high arch feet, and epileptic seizure presented slow response, delayed development, and low limb muscle strength. Electroencephalogram showed abnormal waves, a large number of multifocal sharp waves, sharp slow waves, and multiple spasms with a series of attacks. High-throughput sequencing and Sanger sequencing identified a heterozygous mutation, c.5885G>A (p.R1962H), in the DYNC1H1 gene (NM_001376) of the proband, which was not identified in her parents. Combined with the clinical manifestations and pedigree of this family, this mutation is likely pathogenic based on the American Academy of Medical Genetics and Genomics guidelines. The child was followed when she was 1 year and 2 mo old. The magnetic resonance imaging result was consistent with the findings of white matter myelinated dysplasia and congenital giant gyrus. The extensive neurogenic damage to the extremities was considered, as the results of electromyography showed that the motor conduction velocity and sensory conduction of the nerves of the extremities were not abnormal, and the degree of fit of the children with severe contraction was poor. At present, the child is 80 cm in length and 9 kg in weight, with slender limbs and low muscle strength, and still does not raise her head. She cannot sit or speak. Speech, motor, and mental development was significantly delayed. There is still no effective treatment for this disease. CONCLUSION: We herein report a de novo variant of DYNC1H1 gene, c.5885G>A (p.R1962H), leading to overlapping phenotypes (seizure, general growth retardation, and muscle weakness) of CMT20, MRD13, and SMA-LED, but there is no effective treatment for such condition. Our case enriches the DYNC1H1 gene mutation spectrum and provides an important basis for clinical diagnosis and treatment and genetic counseling.

Mesenchymal stem cells from different sources show distinct therapeutic effects in hyperoxia-induced bronchopulmonary dysplasia in rats.

Mesenchymal stem cells (MSCs) have been shown as an effective medicinal means to treat bronchopulmonary dysplasia (BPD). The widely used MSCs were from Wharton's jelly of umbilical cord (UC-MSCs) and bone marrow (BM-MSCs). Amniotic fluid MSCs (AF-MSCs) may be produced before an individual is born to treat foetal diseases by autoplastic transplantation. We evaluated intratracheal (IT) MSCs as an approach to treat an hyperoxia-induced BPD animal model and compared the therapeutic effects between AF-, UC- and BM-MSCs. A BPD animal model was generated by exposing newborn rats to 95% O2 . The continued stress lasted 21 days, and the treatment of IT MSCs was conducted for 4 days. The therapeutic effects were analysed, including lung histology, level of inflammatory cytokines, cell death ratio and state of angiogenesis, by sacrificing the experimental animal at day 21. The lasting hyperoxia stress induced BPD similar to the biological phenotype. The treatment of IT MSCs was safe without deaths and normal organ histopathology. Specifically, the treatment was effective by inhibiting the alveolar dilatation, reducing inflammatory cytokines, inducing angiogenesis and lowering the cell death ratio. AF-MSCs had better therapeutic effects compared with UC-MSCs in relieving the pulmonary alveoli histological changes and promoting neovascularization, and UC-MSCs had the best immunosuppressive effect in plasma and lung lysis compared with AF-MSCs and BM-MSCs. This study demonstrated the therapeutic effects of AF-, UC- and BM-MSCs in BPD model. Superior treatment effect was provided by antenatal MSCs compared to BM-MSC in a statistical comparison.

Case Report: Two Chinese Infants of Sengers Syndrome Caused by Mutations in AGK Gene.

Sengers syndrome (OMIM #212350) is a rare autosomal recessive disorder due to mutations in acylglycerol kinase (AGK) gene. We report two cases that were diagnosed clinically and confirmed genetically. Both infants had typical clinical features characterized by hypertrophic cardiomyopathy, bilateral cataracts, myopathy, and lactic acidosis, and heart failure was the most severe manifestation. Genetic testing of a boy revealed a homozygous pathogenic variant for Sengers syndrome in AGK (c.1131+2T>C) which was classified as likely pathogenic according to the ACMG guideline; besides, his skeletal muscle biopsy and transmission electron microscope presented obvious abnormity. One girl had compound heterozygous (c.409C>T and c.390G>A) variants of AGK gene that was identified in the proband and further Sanger sequencing indicated that the parents carried a single heterozygous mutation each. After the administration of "cocktail" therapy including coenzyme Q10, carnitine, and vitamin B complex, as well as ACEI, heart failure and myopathy of the boy were significantly improved and the condition was stable after 1-year follow-up, while the cardiomyopathy of the girl is not progressive but the plasma lactate acid increased significantly. We present the first report of two infants with Sengers syndrome diagnosed via exome sequencing in China.

Autosomal dominant tubulointerstitial kidney disease genotype and phenotype correlation in a Chinese cohort.

Genes of UMOD, HNF1B, MUC1, REN and SEC61A1 were reported to be associated with autosomal dominant tubulointerstitial kidney disease (ADTKD). 48 probands and their family members (N = 27) were enrolled in this genetic screening study. A combination of methods was employed for comprehensive molecular analysis of both copy number variations (CNVs) and single nucleotide variants (SNVs). 35 probands were followed for years. The phenotype-genotype and genotype-outcome correlation were inferred from these datasets. In this cohort, 18 probands were diagnosed with ADTKD, according to Kidney Disease: Improving Global Outcomes (KDIGO) guideline. Moreover, 11 probands were diagnosed with ADTKD-UMOD, one with ADTKD-REN and one with ADTKD-HNF1B, based on molecularly confirmed pathogenic variants. The 11 UMOD variants were mainly located in codons 28 to 289 and half of the variants were found to change the cysteine amino acid. According to the follow-up data, suspected ADTKD individuals had a better prognosis compared to ADTKD individuals (p = 0.029). Individuals with a cysteine substitution in the UMOD gene appeared to have a better prognosis than individuals with other amino acid substitutions (p = 0.015).

B-lymphocyte deficiency and recurrent respiratory infections in a 6-month-old female infant with mosaic monosomy 7.

Monosomy 7 is generally considered as an acquired cytogenetic abnormality within hematopoietic cells, and indicates an especially high risk of progression to bone marrow failure, myelodysplastic syndrome (MDS) or juvenile myelomonocytic leukemia (JMML). We report a case of a 6-month-old female infant with mosaic monosomy 7 who presented with clinical and laboratory evidences of immunodeficiency. The patient had suffered from recurrent respiratory infections since she was born. Peripheral blood lymphocyte subsets revealed an extremely low level of CD19+ B lymphocytes (0.3∼0.8%, normal range: 6.4∼22.6%) and a decreased CD4/CD8 ratio (0.67∼1.12, normal range: 1.4∼2.0). Decreased serum levels of IgG (1.53 g/L, normal range: 4.09∼7.03 g/L), IgA (0.10 g/L, normal range: 0.21∼0.47 g/L) and IgM (0.26 g/L, normal range: 0.33∼0.73 g/L) were detected, while complements were normal. Excepting transient neutropenia, routine blood tests were within normal limits. Clinical exome sequencing identified a de novo mosaic monosomy 7, while no pathogenic mutation associated with immunodeficiency was detected. However, peripheral blood cytogenetic analysis was failure to detect monosomy 7 due to the very few cell mitosis. Subsequent fluorescence in situ hybridization (FISH) identified a mosaic monosomy 7 in 58 cells within a total number of 100 cells, which was consistent with clinical exome sequencing. Therefore, the patient was diagnosed with primary immunodeficiency disease (PID) due to mosaic monosomy 7. Intravenous treatment with multiple antibiotic agents and infusion of gamma globulin could control the patient's respiratory infections effectively. A better understanding of PIDs will enable effective treatments and prevention of infections in these patients.

Rapid prenatal diagnosis of skeletal dysplasia using medical trio exome sequencing: Benefit for prenatal counseling and pregnancy management.

OBJECTIVE: The aim of this study is to explore the utility of rapid medical trio exome sequencing (ES) for prenatal diagnosis using the skeletal dysplasia as an exemplar. METHOD: Pregnant women who were referred for genetic testing because of ultrasound detection of fetal abnormalities suggestive of a skeletal dysplasia were identified prospectively. Fetal samples (amniocytes or cord blood), along with parental blood, were send for rapid copy number variations testing and medical trio ES in parallel. RESULTS: Definitive molecular diagnosis was made in 24/27 (88.9%) cases. Chromosomal abnormality (partial trisomy 18) was detected in one case. Sequencing results had explained the prenatal phenotype enabling definitive diagnoses to be made in 23 cases. There were 16 de novo dominant pathogenic variants, four dominant pathogenic variants inherited maternally or paternally, two recessive conditions with pathogenic variants inherited from unaffected parents, and one X-linked condition. The turnaround time from receipt of samples in the laboratory to reporting sequencing results was within 2 weeks. CONCLUSION: Medical trio ES can yield very timely and high diagnostic rates in fetuses presenting with suspected skeletal dysplasia. These definite diagnoses aided parental counseling and decision making in most of cases.

Mutations in both SAMD9 and SLC19A2 genes caused complex phenotypes characterized by recurrent infection, dysphagia and profound deafness - a case report for dual diagnosis.

BACKGROUND: Phenotypic difference is general in Mendelian disease. Due to the extremely low incidence for a single disease, phenotype spectrum needs to be expanded. Meanwhile, earlier knowledge says patients who suffered from two kinds of different Mendelian disease are very rare. CASE PRESENTATION: We describe a case of neonatal male with genital anomalies, growth delay, skin hyperpigmentation, chronic lung disease with recurrent infection, anemia, and severe deafness. Without any clear etiology after routine workflow, whole exome sequencing was carried on. A pathogenic de novo SAMD9 mutation and compound heterozygous likely-pathogenic variants in SLC19A2 were identified. Some symptoms were improved after the patient was treated with vitamin B1. Unfortunately, the boy died from sepsis and multiple organ failure before 1 year old. CONCLUSION: Combining the phenotype and clinical progress of treatment, we report that it is the first case of a patient with both MIRAGE syndrome and TRMA syndrome.

Giant bilateral adrenal myelolipomas in two Chinese families with congenital adrenal hyperplasia.

CONTEXT AND OBJECTIVES: Congenital adrenal hyperplasia (CAH) is one of the most prevalent, and potentially severe, genetic inborn errors of steroid synthesis directly affecting metabolism. Most patients are diagnosed and treated at an early age. There have been very limited reports of adults with CAH-associated adrenal myelolipomas. We aimed to analyze two families with CAH-associated giant adrenal myelolipomas caused by defects in CYP21A2 and CYP17A1 genes. PARTICIPANTS AND METHODS: A total of 14 individuals from two unrelated families were identified with either CYP21A2 or CYP17A1 mutations. Of note, 5 patients were found with adrenal myelolipomas. Total DNA isolated from the peripheral blood of the two probands was screened for potential mutations in the following susceptibility genes of CAH: CYP21A2, CYP11B1, CYP17A1, HSD17B3, HSD3B2, ARMC5, and STAR using Target Capture-Based Deep Sequencing; and Sanger sequencing was conducted for the family members to detect the potential mutations. RESULTS: In family 1, molecular genetics sequencing revealed a compound heterozygous mutation (c.293-13C>G / c.518T>A, p.I173N) in CYP12A2 in the patient and his brother. In family 2, all three female patients with adrenal myelolipomas were found to have a compound heterozygous mutation (c.1118A>T, p.H373L / c.1459_1467del9, p.D487_F489del) in CYP17A1. CONCLUSION: To avoid giant CAH-associated adrenal myelolipomas in adults, it is important to identify CAH early so appropriate treatment can be initiated to interrupt the chronic adrenal hyperstimulation resulting from increased ACTH. Genetic testing and counseling could be useful in CAH.

A Comprehensive Strategy for Accurate Mutation Detection of the Highly Homologous PMS2.

Germline mutations in the DNA mismatch repair gene PMS2 underlie the cancer susceptibility syndrome, Lynch syndrome. However, accurate molecular testing of PMS2 is complicated by a large number of highly homologous sequences. To establish a comprehensive approach for mutation detection of PMS2, we have designed a strategy combining targeted capture next-generation sequencing (NGS), multiplex ligation-dependent probe amplification, and long-range PCR followed by NGS to simultaneously detect point mutations and copy number changes of PMS2. Exonic deletions (E2 to E9, E5 to E9, E8, E10, E14, and E1 to E15), duplications (E11 to E12), and a nonsense mutation, p.S22*, were identified. Traditional multiplex ligation-dependent probe amplification and Sanger sequencing approaches cannot differentiate the origin of the exonic deletions in the 3' region when PMS2 and PMS2CL share identical sequences as a result of gene conversion. Our approach allows unambiguous identification of mutations in the active gene with a straightforward long-range-PCR/NGS method. Breakpoint analysis of multiple samples revealed that recurrent exon 14 deletions are mediated by homologous Alu sequences. Our comprehensive approach provides a reliable tool for accurate molecular analysis of genes containing multiple copies of highly homologous sequences and should improve PMS2 molecular analysis for patients with Lynch syndrome.

Recurrent ACADVL molecular findings in individuals with a positive newborn screen for very long chain acyl-coA dehydrogenase (VLCAD) deficiency in the United States.

Very long chain acyl-coA dehydrogenase deficiency (VLCADD) is an autosomal recessive inborn error of fatty acid oxidation detected by newborn screening (NBS). Follow-up molecular analyses are often required to clarify VLCADD-suggestive NBS results, but to date the outcome of these studies are not well described for the general screen-positive population. In the following study, we report the molecular findings for 693 unrelated patients that sequentially received Sanger sequence analysis of ACADVL as a result of a positive NBS for VLCADD. Highlighting the variable molecular underpinnings of this disorder, we identified 94 different pathogenic ACADVL variants (40 novel), as well as 134 variants of unknown clinical significance (VUSs). Evidence for the pathogenicity of a subset of recurrent VUSs was provided using multiple in silico analyses. Surprisingly, the most frequent finding in our cohort was carrier status, 57% all individuals had a single pathogenic variant or VUS. This result was further supported by follow-up array and/or acylcarnitine analysis that failed to provide evidence of a second pathogenic allele. Notably, exon-targeted array analysis of 131 individuals screen positive for VLCADD failed to identify copy number changes in ACADVL thus suggesting this test has a low yield in the setting of NBS follow-up. While no genotype was common, the c.848T>C (p.V283A) pathogenic variant was clearly the most frequent; at least one copy was found in ~10% of all individuals with a positive NBS. Clinical and biochemical data for seven unrelated patients homozygous for the p.V283A allele suggests that it results in a mild phenotype that responds well to standard treatment, but hypoglycemia can occur. Collectively, our data illustrate the molecular heterogeneity of VLCADD and provide novel insight into the outcomes of NBS for this disorder.

A novel EBP c.224T>A mutation supports the existence of a male-specific disorder independent of CDPX2.

Mutations in the Emopamil-binding protein (EBP) gene cause X-linked dominant chondrodysplasia punctata 2 (CDPX2), a disorder in which at least 95% of liveborn individuals are female and male intrauterine lethality is assumed. Several affected males with mutations in EBP have been reported. These males exhibit a phenotype similar to CDPX2 due to either somatic mosaicism or a 47, XXY karyotype in association with a null EBP allele. Alternatively, affected males may exhibit a distinct phenotype if they are hemizygous for a hypomorphic allele of EBP. Recently, we described a novel X-linked phenotype associated with digital abnormalities, intellectual disability and short stature, and mapped it to Xp11.4-p11.21. X-exome sequencing was performed to identify the mutated gene responsible for this phenotype. A novel missense variant, c.224T>A (p.I75N), was identified in EBP. SIFT and PolyPhen-2 predicted this change to be deleterious. The pathogenicity of this variant was subsequently supported by increased plasma levels of 8(9)-cholestenol in the proband and his mother. The molecular and biochemical evidence convincingly supports the pathogenicity and association of the p.I75N mutation with this newly described phenotype. This study expands the current phenotypic spectrum of males with hypomorphic EBP mutations and supports to the hypothesis that there exists an X-linked recessive entity independent of CDPX2.

Massively parallel sequencing for diagnosing clinically and genetically heterogeneous disorders.

Massively parallel sequencing technology has great potential to identify the precise molecular causes of human disorders, which were once considered difficult to diagnose for either inherited Mendelian or oncological diseases. Besides being a valuable tool for gene discovery, this technology has also gained tremendous momentum in clinical molecular diagnostic laboratories. There are a wide variety of clinical applications recently developed to meet the clinical demands for personalized medicine. This article discusses these up-to-date massively parallel sequencing clinical applications and emphasizes various disorders that can be targeted, as well as some challenges faced in the process of implementing these assays in the clinical setting.