NOTCH3 Variants in Patients with Suspected CADASIL.

Background: Cerebral autosomal dominant arteriopathy with subcortical infarctions and leukoencephalopathy (CADASIL) is the most common hereditary form of cerebral small vessel disease. It is clinically, radiologically, and genetically heterogeneous and is caused by NOTCH3 mutations. Methods: In this study, we analyzed NOTCH3 in 368 patients with suspected CADASIL using next-generation sequencing. The significant variants detected were reported along with the clinical and radiological features of the patients. Results: Heterozygous NOTCH3 changes, mostly missense mutations, were detected in 44 of the 368 patients (~12%). Conclusions: In this single-center study conducted on a large patient group, 30 different variants were detected, 17 of which were novel. CADASIL, which can result in mortality, has a heterogeneous phenotype among individuals in terms of clinical, demographic, and radiological findings regardless of the NOTCH3 variant.

ATP7B Gene Variant Profile Identified by NGS in Wilson's Disease.

Background: Wilson's disease (WD) is a copper metabolism disorder caused by ATP7B gene mutations and shows an autosomal recessive pattern of inheritance. We aimed to contribute to the mutation profile of ATP7B and show demographic and phenotypic differences in this study. Materials and methods: The clinical and demographic characteristics of patients who underwent ATP7B gene sequence analysis using next-generation sequencing were evaluated to improve genotype-phenotype correlation in WD. Results: An uncertain significance (D563N) and seven likely pathogenic (Y532D, Y715Y, T977K, K1028*, E1086K, A1227Pfs*103, and E1242K) variants were identified as associated with WD. Uniparental disomy was detected in one case. Conclusion: Our work expanded the ATP7B variant spectrum and pointed to clinical heterogeneity in ATP7B variants among patients with WD. All symptomatic patients had hepatic involvement and were clinically and/or genetically diagnosed with WD in the pediatric period. T977K, A1003V, H1069Q, E1086K, and N1270S variants were associated with hepatic failure.

Clinical significance of hypouricemia in children and adolescents.

BACKGROUND: Although hyperuricemia is a widely studied condition with well-known effects on the kidneys, hypouricemia is usually considered a biochemical abnormality of no clinical significance despite the fact that it can be a sign or major finding of serious metabolic or genetic diseases affecting kidney health. In this study, we aimed to investigate and emphasize the clinical significance of hypouricemia. METHODS: Patients were evaluated retrospectively for persistent hypouricemia defined as serum uric acid concentrations of < 2 mg/dL on at least 3 different occasions. According to the blood and urine uric acid (UA) levels, the patients were classified as having hypouricemia due to UA underproduction vs. overexcretion. Demographic, clinical, and genetic characteristics were noted for analysis. RESULTS: Fourteen patients (n = 14; M/F 8/6) with persistent hypouricemia were identified. Hypouricemia due to underproduction was the cause of 42.8% of these cases. All of the patients with a uric acid level of 0 mg/dL (n = 4) had hypouricemia due to underproduction. The median serum uric acid level was 0.85 (0-1.6) mg/dL. Isolated hypouricemia and hypouricemia with metabolic acidosis were equally distributed. Among the patients with hypouricemia due to underproduction, the final diagnoses were xanthine dehydrogenase deficiency (n = 5) and alkaptonuria (n = 1). In the overexcretion group, the final diagnoses were nephropathic cystinosis (n = 6), distal renal tubular acidosis (n = 1), and hereditary renal hypouricemia (n = 1). The diagnostic lag was longer for patients with isolated hypouricemia compared to other patients (p = 0.001). CONCLUSIONS: Hypouricemia may reflect underlying genetic or metabolic diseases, early diagnosis of which could help preserve kidney function. A higher resolution version of the Graphical abstract is available as Supplementary information.

Clinical exome sequencing findings in 1589 patients.

Clinical exome sequencing (CES) is important for the diagnosis of Mendelian diseases, which are clinically and etiologically heterogeneous. Sharing of large amounts of CES data associated with clinical findings will increase the accuracy of variant interpretation. We performed a retrospective study to state the diagnostic yield of CES in 1589 patients with a wide phenotypic spectrum. CES was performed using the Sophia Clinical Exome Sequencing Kit with 4493 genes, followed by sequencing on a NextSeq 500 system. The diagnosis rate was 36.8% when only pathogenic and likely pathogenic variants were included. Consanguineous unions and positive family history were associated with a high diagnostic yield. The neurological disease group had the highest number of patients. The groups with high diagnosis rates were ear, eye, and muscle disease groups. Seven candidate genes (EFHC2, HSPB3, FAAH2, ITGB1, GYG2, CD177, and CSTF2T) that are not yet associated with human diseases were identified. Owing to the high diagnostic yield of CES compared with that of other genetic tests, it can be used as a standard diagnostic test in patients with rare genetic disorders that require a wide differential diagnosis, especially in laboratories with limited resources.

Lathosterolosis: a rare cholesterol metabolism disorder with a wide range of clinical variability.

OBJECTIVES: Lathosterolosis is a rare autosomal recessive congenital disease that occurs due to homozygous or compound heterozygous mutations in the sterol C5-desaturase (SC5D) gene. We report a male patient with biallelic missense variant detected in the SC5D gene. CASE PRESENTATION: An eight-month-old male patient was referred to the department of paediatric neurology for status epilepticus. He had no remarkable dysmorphic features except micrognathia, ptotic ear and thin-stranded hair. Laboratory tests revealed an alanine aminotransferase level of 502 IU/L and an aspartate aminotransferase level of 279 IU/L; other biochemical test results were normal. The brain MRI revealed atrophic changes in both hemispheres. A decrease in the volume of brain stem and thin corpus callosum were noticeable. Whole exome sequencing was performed because of consanguineous marriage and sibling death in his medical history, and the encountered features were consistent with suspected neurometabolic disease in the cranial imaging and the presence of borderline psychomotor retardation. A biallelic missense variant, c.656T>C p.(Leu219Ser), was identified in the SC5D gene. CONCLUSIONS: Lathosterolosis is a rare cholesterol metabolism disorder and can be presented with a wide range of clinical features by newly reported cases. Lathosterolosis should be considered in cases with cataracts, delayed neuromotor developmental milestones and high levels of liver enzymes.

Newly defined peroxisomal disease with novel ACBD5 mutation.

Peroxisomal disorders are a heterogeneous group of diseases caused by mutations in a large number of genes. One of the genetic disorders known to cause this situation is ACBD5 (Acyl-CoA binding-domain-containing-5) gene mutations that have been described in recent years. Here, we report two siblings with a novel homozygous nonsense variation (c.1297C>T, p.Arg433*) in ACBD5 (NM_145698.4) gene using Clinical Exome Sequencing (Sophia Genetics).

Clinical features of pediatric renal glucosuria cases due to SLC5A2 gene variants.

BACKGROUND: Familial renal glycosuria (FRG) is a rare renal tubular disorder characterized by a variable loss of glucose in the urine despite normal blood glucose levels, which is seen in a condition in which other tubular functions are preserved. In this study, the molecular and clinical characteristics of pediatric FRG cases due to SLC5A2 gene variants were defined. METHODS: Demographic features, diagnostic tests, and molecular analyses of patients with a diagnosis of FRG cases due to SLC5A2 gene variants were retrospectively analyzed between 2016 and 2019. RESULTS: The data of 16 patients who were clinically and genetically diagnosed with FRG in a 4-year period were analyzed. Seven (44%) of the cases were female and 9 (56%) were male. The median age at diagnosis was 6 years old (2 months old to 17 years old). Neuromotor development was found to be appropriate for the age in each case. Systemic blood pressure was evaluated as normal. A homozygous pathogenic variant in the SLC5A2 gene was detected in 14 patients in the genetic examination. A heterozygous variant was detected in one patient. In the other patient, two different heterozygous pathological variants were found in the SLC5A2 gene. CONCLUSIONS: It was revealed that growth and development were normal in children with glucosuria due to variations in the SCL5A2 gene. Renal function tests and urinary amino acid excretion were also within normal values. In our case series, the most common genetic variation in the SCL5A2 gene was the A219T (c.655G>A) variant.

A Novel Homozygous Mutation in the MYO5B Gene Associated With Normal-Gamma-Glutamyl Transferase Progressive Familial Intrahepatic Cholestasis.

The genetic defect of MYO5B is usually associated with microvillus inclusion disease (MVID). MYO5B mutations are one of the rare causes of progressive familial intrahepatic cholestasis (PFIC) with normal/low gamma-glutamyl transferase (GGT). In this report, we discuss the case of a nine-month-old girl with low-GGT cholestasis whose next-generation sequencing (NGS) showed a homozygous splicing variation (c.3045+3A>T) on the MYO5B (NM_001080467) gene, which was a novel mutation. We identified that this mutation had a disease-causing effect in silico analysis.

Approaches for diagnosis and treatment in neurotransmitter disorders of childhood.

Neurotransmitter disorders are a group of neurometabolic syndromes caused by disturbances of neurotransmitter metabolism. The primary aim of this retrospective study is to present patients with disturbances of monoamine neurotransmitter metabolism. Cerebrospinal fluid (CSF) neurotransmitter measurements and genetic analysis were performed on five patients. Five patients who had various movement disorders and motor and cognitive disabilities were included. Four patients were diagnosed with sepiapterin reductase (SR) deficiency, and one was diagnosed with aromatic L-amino acid decarboxylase (AADC) deficiency. Different treatment responses appeared in patients with SR and AADC deficiency. The responses to drug treatment ranged from good to weak in our patients. The diagnosis process is challenging in patients with SR and AADC deficiency, which present similar clinical features to other neurological and metabolic diseases. Investigations of neurotransmitters in CSF and analysis of related genes are essential to differentiate disturbances of monoamine neurotransmitter metabolism from other neurometabolic diseases. For patients with monoamine neurotransmitter disorders, drugs that target these disturbances should be combined as necessary to produce the appropriate response.

Expanding the clinical spectrum in trichohepatoenteric syndrome.

Trichohepatoenteric syndrome (THES) is a very rare autosomal recessive genetic disorder, which is characterized by intractable diarrhea during infancy, dysmorphic features, immunodeficiency, and a failure to thrive. There are still significant difficulties for patients and clinicians in terms of the management of THES, even though its molecular basis has been uncovered in the last decade. In this article, we have presented two cases relating to siblings that have been diagnosed with the condition. Concerning one of the patients, we described a novel variation (c.2114 + 5G > A) in the TTC37 gene and a mild clinical course; meanwhile, the other one was clinically diagnosed with THES at 17 years of age, but they had seizures and died suddenly. These cases expand the spectrum of clinical findings in relation to THES.

Recently defined epileptic encephalopathy related to WWOX gene mutation: six patients and new mutations.

Purpose: Pathogenic variants of the WWOX gene have been linked to sexual differentiation disorders, spinocerebellar ataxia, and epileptic encephalopathy (EE). We evaluated the clinical and molecular data from six newly diagnosed patients with WWOX-related EE.Methods: Clinical and molecular findings in six patients with EE were investigated, and biallelic pathogenic variants in the WWOX gene were identified. Clinical exome sequencing and Sanger sequencing were performed.Results: Three variations, as well as two novel mutations, in the WWOX gene were detected.Conclusion: Pathogenic WWOX mutations are associated with early-onset EE. Here, we report the case of six children with WWOX-related EE.

Alkaptonuria in Turkey: Clinical and molecular characteristics of 66 patients.

Alkaptonuria (AKU) is an inborn error of metabolism caused by the deficiency of homogentisate 1,2-dioxygenase (HGD) as a result of a defect in the HGD gene. HGD enzyme deficiency results in accumulation of homogentisic acid (HGA) in the body, which in turn leads to multisystemic clinical symptoms. The present study aimed to investigate the presenting symptoms, age at diagnosis, and clinical and genetic characteristics of AKU patients followed-up in different centers in Turkey. In this cross-sectional, multicenter, descriptive study, medical records of 66 AKU patients were retrospectively evaluated. Patients' data regarding demographic, clinical and genetic characteristics were recorded. HGD database (http://hgddatabase.cvtisr.sk/) was used to identify HGD gene variants. Of the patients, 37 (56.1%) presented with isolated dark urine and 29 (43.9%) were diagnosed based on the clinical symptoms or family screening. One of these patients was on follow-up for 2 years due to Parkinsonism and was diagnosed with AKU on further analyses. Signs of ochronosis such as joint pain, low back pain and renal stones developed in childhood in 7 patients. Eight patients were diagnosed with depression via psychiatric evaluation. There were 14 (21.2%) patients operated on for ochronosis. The most frequent mutation observed in the patients was c.175delA, which was followed by c.674G > A and c.1007-2A > T mutations. Four novel mutations (c.189G > A, c.549+1G > T, c.1188+1G > A, and c.334 T > G) were identified in the patients included in the study. In addition to the known signs such as dark urine and skin pigmentation, symptoms involving different systems such as neurological findings and depression can also be encountered in AKU patients. The presence of a change in urine color needs to be questioned in patients presenting with different symptoms such as arthralgia/arthritis, renal stones or low-back pain, particularly in childhood, when skin ochronosis is not pronounced, and further examination should be performed.

A Novel Nonsense FMN2 Mutation in Nonsyndromic Autosomal Recessive Intellectual Disability Syndrome.

Introduction Genetic causes of the intellectual disability Nonsyndromic Autosomal-Recessive Intellectual Disability Syndrome (MRT47, MIM 616193) are mutations in the recently described FMN2 (formin 2 gene). Case report: A boy with intellectual disability had a novel homozygous nonsense mutation (c.2245C > T/p.Gln749*) leading to a premature stop codon in exon 6 of the FMN2 (NM_001305424) gene detected by Clinical Exome Sequencing (CES). Conclusion: Clinical features of a patient with a novel nonsense FMN2 mutation is presented. We urge the change in the OMIM nomenclature from Mental Retardation, Autosomal Recessive 47 (MRT47, MIM 616193) to 'Nonsyndromic Autosomal-Recessive Intellectual Disability Syndrome'.

First Infertile Case with CSTF2TGene Mutation.

Male infertility is multifactorial and presents with heterogeneous phenotypic features. Genetic factors are responsible for up to 15% of the male infertility cases. Loss of the Cstf2t gene in male mice results in infertility. No disease-associated mutations have been described for this gene in infertile men. Here, we report a patient diagnosed with infertility in whom a homozygous nonsense mutation in the CSTF2T gene was detected by clinical exome sequencing. This case is the first description of an infertile patient who has a homozygous CSTF2T mutation.

Two patients with glutaric aciduria type 3: a novel mutation and brain magnetic resonance imaging findings.

BACKGROUND: Glutaric Aciduria Type 3 (GA-3) is a rare metabolic disease which is inherited autosomal recessively and characterized by isolated glutaric acid excretion. To date, a limited number of cases have been reported in the literature. We present two patients with GA3 who were diagnosed with the isolated increased level of glutaric acid in urine. CASE: Glutaric aciduria type 1 and type 2 were excluded by genetic analysis and other laboratory and clinical findings. One of our patients had a homozygous mutation p.Arg322Trp (c.964C > T) of SUGCT (NM_001193311) gene. To the best of our knowledge this mutation has not been reported in the literature previously. Symmetrical periventricular and deep cerebral white matter abnormalities were detected on his brain magnetic resonance imaging (MRI). CONCLUSION: We present two patients with GA-3 and a novel mutation in the SUGCT gene. Our findings expand the spectrum of causative mutations and clinical findings in GA-3.

Novel PLVAP Mutation in Protein Losing Enteropathy.

Introduction: A genetic cause of the protein-losing enteropathy (PLE) disease Diarrhea 10 (DIAR10) are mutations in the recently described PLVAP (plasmalemma vesicle protein). Case report: An infant with fatal PLE had a novel homozygous frameshift mutation (c.339dupT; p.Ala114Cysfs*9) leading to a premature stop codon in exon 1 of the PLVAP (NM_031310) gene detected by Whole Exome Sequencing (WES). Conclusion: The frameshift mutation (PLVAP; c.339dupT; p.Ala114Cysfs*9) we have described in our patient has not been previously reported. This is the fifth case reported with a mutation in PLVAP associated with PLE and DIAR10.

Glutathione S-transferase T1, M1 and P1 Genetic Polymorphisms and Susceptibility to Colorectal Cancer in Turkey.

Colorectal cancer (CRC) is reported to be the third most common cancer worldwide and the fourth most common cause of cancer related deaths. CRC is considered to be a multifactorial disease whose risk varies due to the complex interaction between individual genetic basis and exposure to multiple endogenous factors. Glutathione S-transferases are pro-carcinogenic in CRC and are required for the conjugation between chemotherapeutics and broad spectrum xenobiotics. One hundred and eleven patients with CRC and 128 control subjects without any cancer history were enrolled in this study. Multiplex PCR was applied to determine polymorphisms for the GSTT1 and M1 genes, and PCR-RFLP was applied for the GSTP1 (Ile105Val) gene polymorphism. Values <0.05 were defined as statistically significant. We detected a significant high correlation between predisposition for CRC and presence of the Ile/Ile genotype of the GSTP1 (IIe105Val) gene polymorphism, but we did not find a significant relationship between predisposition for CRC and GSTT1 and M1 deletion polymorphisms. In addition, we did not determine a relationship between GSTT1, M1 and P1 gene polymorphisms and any clinicopathological features of CRC. GSTT1 null/GSTM1 positive and GSTT1 null/GSTM1 positive/GSTP1 Ile/ Ile genotypes were significantly higher in the patient group. Our results revealed that there is no relationship among CRC, its clinicopathologic features, and GSTT1 M1 gene polymorphisms. However, there was a significant correlation between CRC and the GSTP1 Ile/Ile genotype. Further studies with larger patient groups are required to delineate the relationships between GST gene polymorphisms and the clinicopathologic features of CRC in Turkey.

Spectrum of EGFR gene mutations and ALK rearrangements in lung cancer patients in Turkey.

The EGFR gene and ALK rearrangements are two genetic drivers of non-small cell lung cancer (NSCLC). The frequency of EGFR mutations and ALK rearrangement varies according to not only ethnicity but also gender, smoking status and the histological type of NSCLC. In the present study, we demonstrated the distribution of EGFR mutations in 132 NSCLC patients by using a pyrosequencing technique and the distribution of ALK rearrangements in 51 NSCLC patients by using fluorescent in situ hybridization technique in Turkey. Additionally, we compared the clinicopathological data of NSCLC patients with the mutation status of EGFR in their cancerous tissues. Both EGFR mutations and ALK rearrangements were identified in 19 (14.39 %) and 1 (1.96 %) patients, respectively. We found EGFR mutations in codon 861, 719 and 858 with the ratios of 10.52 % (2/19), 10.52 % (2/19) and 31.58 % (6/19), respectively, and deletion of exon 19 in 47.37 % (9/19) of the patients. We found the frequency of EGFR mutations to be significantly higher in female patients and nonsmokers (p = 0.043, p = 0.027, respectively). Consequently, we found EGFR mutations to be more frequent in female patients and nonsmokers. Future studies on larger patient groups would provide more accurate data to exhibit the relationship between EGFR mutations and ALK rearrangements and the clinicopathological status.