Congenital sucrase-isomaltase deficiency in Türkiye; a single center experience.

BACKGROUND: Congenital sucrase-isomaltase deficiency (CSID) is a rare inherited carbohydrate malabsorption disorder caused by sucrase-isomaltase (SI) gene variants. In CSID, an autosomal recessively inherited disease, symptoms can also be seen in individuals with heterozygous mutations. METHODS: The variant spectrum was evaluated retrospectively in individuals who presented with chronic diarrhea between 2014 and 2022 and had undergone genetic testing of the SI gene considering CSID due to diet-related complaints. RESULTS: Ten patients with chronic diarrhea were genetically evaluated with SI gene sequencing. In patients diagnosed with CSID and whose symptoms improved with enzyme replacement therapy, the genetic mutation zygosity was found to be heterozygous at a rate of 90%. In 10% of the patients, the mutation was homozygous. Limiting consuming sucrose and isomaltose foods reduced the patients' complaints, but the symptoms did not disappear completely. With the initiation of sacrosidase enzyme replacement therapy, the patient's complaints completely disappeared. CONCLUSION: In CSID, defined as an autosomal recessive disease, clinical symptoms can also be seen in heterozygous cases previously described as carriers, and these patients also benefit from sacrosidase enzyme replacement therapy. In light of these findings, the autosomal recessive definition of CSID does not fully characterize the disease.What is Known:CSID is a rare inherited carbohydrate malabsorption disorder caused by sucrase-isomaltase gene variants.In congenital sucrase-isomaltase deficiency, an autosomal recessively inherited disorder, symptoms can also be seen in individuals with heterozygous mutations.What is new:Severe disease symptoms can also be seen in heterozygous cases, which were thought to be carriers because the disease was previously described as autosomal recessive.Sacrosidase enzyme replacement therapy also eliminates the disease symptoms in patients with heterozygous CSID mutations.This is the second study on sucrase-isomaltase enzyme deficiency pediatric groups in Türkiye and Europe.

This is the study to evaluate the congenital sucrase-isomaltase enzyme deficiency in chronic diarrhea cases covering adults and childhood in our country and the clinical features and treatment response characteristics of the variants detected in these patients.In addition, another aim of our study is that sucrase­isomaltase enzyme deficiency should be considered in the differential diagnosis and should be kept in mind, especially in cases with chronic diarrhea whose cause cannot be determined in childhood.

A CASE OF ALSTRÖM SYNDROME WITH A NOVEL VARIANT IN ALMS1 GENE PRESENTING WITH CONE ROD DYSTROPHY AS FIRST FINDING.

PURPOSE: Alström Syndrome (AS) is a rare autosomal recessive monogenic ciliopathy which is caused by a mutation of the Alström syndrome 1 (ALMS1) gene. It is a multisystemic disorder characterized by insulin resistance, childhood obesity, cardiomyopathy, progressive hepatic and renal failure, sensorineural hearing loss and retinal degeneration. Herein, we aimed to report a novel variant in ALMS1 gene causing AS in a patient presenting with visual impairment. METHODS: Case report. RESULTS: A 10-year-old male patient presented with photophobia and visual impairment in both eyes. Anterior and posterior segment examinations were unremarkable bilaterally. Optical coherence tomography (OCT) showed attenuated ellipsoid zone. Electroretinography revealed diminished cone and rod responses consistent with cone rod dystrophy (CRD). Genetic testing demonstrated a novel homozygous variant in ALMS1 (NM_015120.4) gene. The patient also was found to have early-stage dilated cardiomyopathy through systemic evaluation after the diagnosis of AS. CONCLUSION: Cone-rod dystrophy in pediatric population is relatively rare condition that can be associated with syndromic ciliopathies. The authors presented a case of AS with a novel variant in ALMS1 gene based on ophthalmic findings. Ophthalmologists play an important role in the diagnosis of this syndrome and early detection of systemic manifestations.

Ocular Manifestations of Fabry Disease: Report from a Tertiary Eye Care Center in Türkiye.

Objectives: To report ocular manifestations in patients with Fabry disease (FD) from a tertiary eye care center in Türkiye. Materials and Methods: This prospective, cross-sectional study included 30 eyes of 15 patients with FD. The diagnosis of FD was made based on a combination of clinical findings, genetic analysis, and biochemical evaluation. All participants underwent a detailed ophthalmic examination with special focus on the typical ocular features of FD (cornea verticillata, conjunctival aneurysms, cataract, retinal vessel tortuosity). Results: The mean age was 45±17 years (range: 22-75 years), with a female/male ratio of 2:3. All patients had tortuous conjunctival vessels and 12 patients (80%) had conjunctival aneurysms. Cornea verticillata was present in 10 patients (66.6%), lens opacification in 4 patients (26.6%), and retinal vascular tortuosity in 8 patients (53.3%). All patients had at least two different ocular findings; most (3 heterozygotes/7 hemizygotes) had a combination of corneal verticillata and conjunctival vessel abnormality. The conjunctiva, cornea, and retina were affected together in 5 hemizygous patients (33.3%). One hemizygous patient had all FDrelated ocular manifestations in both eyes. Conclusion: To our knowledge, this study is the first to describe the ocular manifestations of FD in the Turkish population. Although cornea verticillata is considered a hallmark of FD, it was absent in approximately one-third of patients. Moreover, cataract, another well-known feature of FD, was present in only 26.6% of the patients. Conjunctival vascular abnormality alone seems to be quite rare in FD, although it often accompanies other ocular manifestations. Therefore, recognition of other mild findings and special consideration of their associations may increase the diagnostic value of ocular findings in FD.

Effectiveness of whole exome sequencing analyses in the molecular diagnosis of osteogenesis imperfecta.

OBJECTIVES: Osteogenesis imperfecta (OI) is a group of phenotypically and genetically heterogeneous connective tissue disorders that share similar skeletal anomalies causing bone fragility and deformation. This study aimed to investigate the molecular genetic etiology and to determine the relationship between genotype and phenotype in OI patients with whole exome sequencing (WES). METHODS: Multiplex-Ligation dependent Probe Amplification (MLPA) analysis of COL1A1 and COL1A2 and WES were performed on cases between the ages of 0 and 18 whose genetic etiology could not be determined before using a targeted next-generation sequencing panel, including 13 genes (COL1A1, COL1A2, IFITM5, SERPINF1, CRTAP, P3H1, PPIB, SERPINH1, FKBP10, SP7, BMP1, MBTPS2, PLOD2) responsible for OI. RESULTS: Twelve patients (female/male: 4/8) from 10 different families were included in the study. In 6 (50 %) families, consanguineous marriage was noted. The clinical typing based on Sillence classification; 3 (25 %) patients were considered to be type I, 7 (58.3 %) type III, and 2 (16.7 %) type IV. Deletion/duplication wasn't detected in the COL1A1 and COL1A2 genes in the MLPA analysis of the patients. Twelve patients were molecularly analyzed by WES, and in 6 (50 %) of them, a disease-causing variant in three different genes (FKBP10, P3H1, and WNT1) was identified. Two (33.3 %) detected variants in all genes have not been previously reported in the literature and were considered deleterious based on prediction tools. In 6 cases, no variants were detected in disease-causing genes. CONCLUSIONS: This study demonstrates rare OI types' clinical and molecular features; genetic etiology was determined in 6 (50 %) 12 patients with the WES analysis. In addition, two variants in OI genes have been identified, contributing to the literature.

Molecular Genetic Diagnosis with Targeted Next Generation Sequencing in a Cohort of Turkish Osteogenesis Imperfecta Patients and Their Genotype-phenotype Correlation.

Introduction: Osteogenesis imperfecta (OI) is a group of phenotypically and genetically heterogeneous connective tissue disorders that share similar skeletal anomalies causing bone fragility and deformation. This study aimed to investigate the molecular genetic etiology and determine the relationship between genotype and phenotype in OI patients with targeted next-generation sequencing (NGS). Method: In patients with OI, a targeted NGS analysis panel (Illumina TruSight One) containing genes involved in collagen/bone synthesis was performed on the Illumina Nextseq550 platform. Results: Fifty-six patients (female/male: 25/31) from 46 different families were enrolled in the study. Consanguinity between parents was noted in 15 (32.6%) families. Clinically according to Sillence classification; 18(33.1%) patients were considered to type I, 1(1.7%) type II, 26(46.4%) type III and 11(19.6%) type IV. Median body weight was -1.1 (-6.8, - 2.5) SDS, and height was -2.3 (-7.6, - 1.2) SDS. Bone deformity was detected in 30 (53.5%) of the patients, while 31 (55.4%) were evaluated as mobile. Thirty-six (60.7%) patients had blue sclera, 13 (23.2%) had scoliosis, 12 (21.4%) had dentinogenesis imperfecta (DI), and 2 (3.6%) had hearing loss. Disease-causing variants in COL1A1 and COL1A2 genes were found in 24 (52.1%) and 6 (13%) families, respectively. In 8 (17.3%) of the remaining 16 (34.7%) families, the NGS panel revealed disease-causing variants in three different genes (FKBP10, SERPINF1, and P3H1). Nine (23.6%) of the variants detected in all investigated genes were not previously reported in the literature and were classified to be pathogenic according to ACMG guidelines pathogenity scores. In ten (21.7%) families, a disease-related variant was not found in a total of 13 OI genes included in the panel. Conclusion: Genetic etiology was found in 38 (82.6%) of 46 families by targeted NGS analysis. In addition, 9 new variants were assessed in known OI genes which is a significant contribution to the literature.

Multinational experience with next-generation sequencing: opportunity to identify transthyretin cardiac amyloidosis and Fabry disease.

Background: Sarcomeric hypertrophic cardiomyopathy (HCM) must be differentiated from phenotypically similar conditions because clinical management and prognosis may greatly differ. Patients with unexplained left ventricular hypertrophy require an early, confirmed genetic diagnosis through diagnostic or predictive genetic testing. We tested the feasibility and practicality of the application of a 17-gene next-generation sequencing (NGS) panel to detect the most common genetic causes of HCM and HCM phenocopies, including treatable phenocopies, and report detection rates. Identification of transthyretin cardiac amyloidosis (ATTR-CA) and Fabry disease (FD) is essential because of the availability of disease-specific therapy. Early initiation of these treatments may lead to better clinical outcomes. Methods: In this international, multicenter, cross-sectional pilot study, peripheral dried blood spot samples from patients of cardiology clinics with an unexplained increased left ventricular wall thickness (LVWT) of ≥13 mm in one or more left ventricular myocardial segments (measured by imaging methods) were analyzed at a central laboratory. NGS included the detection of known splice regions and flanking regions of 17 genes using the Illumina NextSeq 500 and NovaSeq 6000 sequencing systems. Results: Samples for NGS screening were collected between May 2019 and October 2020 at cardiology clinics in Colombia, Brazil, Mexico, Turkey, Israel, and Saudi Arabia. Out of 535 samples, 128 (23.9%) samples tested positive for pathogenic/likely pathogenic genetic variants associated with HCM or HCM phenocopies with double pathogenic/likely pathogenic variants detected in four samples. Among the 132 (24.7%) detected variants, 115 (21.5%) variants were associated with HCM and 17 (3.2%) variants with HCM phenocopies. Variants in MYH7 (n=60, 11.2%) and MYBPC3 (n=41, 7.7%) were the most common HCM variants. The HCM phenocopy variants included variants in the TTR (n=7, 1.3%) and GLA (n=2, 0.4%) genes. The mean (standard deviation) ages of patients with HCM or HCM phenocopy variants, including TTR and GLA variants, were 42.8 (17.9), 54.6 (17.0), and 69.0 (1.4) years, respectively. Conclusions: The overall diagnostic yield of 24.7% indicates that the screening strategy effectively identified the most common forms of HCM and HCM phenocopies among geographically dispersed patients. The results underscore the importance of including ATTR-CA (TTR variants) and FD (GLA variants), which are treatable disorders, in the differential diagnosis of patients with increased LVWT of unknown etiology.

Investigation of the molecular genetic causes of non-syndromic primary ovarian ınsufficiency by next generation sequencing analysis

ABSTRACT Objective: The aim of this study is to investigate the molecular genetic causes of non-syndromic primary ovarian insufficiency (POI) cases with the gene panel based on next generation sequencing analysis and to establish the relationship between genotype and phenotype. Subjects and methods: Twenty three cases aged 14-40 years followed up with POI were included. Patients with a karyotype of 46, XX, primary or secondary amenorrhea before the age of 40, with elevated FSH (>40 IU/mL) and low AMH levels (<0.03 ng/mL) were included in the study. Molecular genetic analyzes were performed by the next generation sequencing analysis method targeted with the TruSightTM Exome panel. Results: Median age of the cases was 17.8 (14.0-24.3) years, and 12 (52%) cases admitted before the age of 18. Fifteen (65%) patients had consanguineous parents. In 2 (8.6%) cases, variants detected were in genes that have been previously proven to cause POI. One was homozygous variant in FIGLA gene and the other was homozygous variant in PSMC3IP gene. Heterozygous variants were detected in PROK2, WDR11 and CHD7 associated with hypogonadotropic hypogonadism, but these variants are insufficient to contribute to the POI phenotype. Conclusion: Genetic panels based on next generation sequencing analysis technologies can be used to determine the molecular genetic diagnosis of POI, which has a highly heterogeneous genetic basis.