A Second Family with Myhre Syndrome Caused by the Same Recurrent SMAD4 Pathogenic Variation (p.Arg496Cys)

Introduction: Myhre syndrome (MS; OMIM #139210) is a rare connective tissue disorder presenting with cardiovascular, respiratory, gastrointestinal, and skeletal system findings. Fewer than 100 patients were reported until recently, and all molecularly confirmed cases had de novo heterozygous gain-of-function mutations in the SMAD4 gene. Dysregulation of the TGF-beta signaling pathway leads to axial and appendicular skeleton, connective tissue, cardiovascular system, and central nervous system abnormalities. Case Presentation: Two siblings, 12 and 9 years old, were referred to us because of intellectual disability, neurodevelopmental delay, and dysmorphic facial features. Physical examination revealed hypertelorism, strabismus, small mouth, prognathism, short neck, stiff skin, and brachydactyly. Discussion: With a clinical diagnosis of MS, the SMAD4 gene was analyzed via Sanger sequencing, and a heterozygous c.1486C>T (p.Arg496Cys) pathogenic variation was detected in both of the siblings. The segregation analysis revealed that the mutation was inherited from the father who displayed a milder phenotype. Among the 90 patients in the literature, one family was reported in which two siblings carried the same variation (p.Arg496Cys), inherited from the severely affected mother. We are reporting the second family which has three affected family members, a father and two children. We report this study to remind the clinicians to be aware of the parental transmission of SMAD4 variations and also evaluate the parents of the Myhre cases

Türk Toplumunda Kalıtsal Kanser Sendromu Hastalarında Çoklu Gen Panel Taraması

@ 2022 by the Istanbul Medeniyet University.Objective: Hereditary cancer syndromes (HCSs) are a heterogenous group of disorders caused by germline pathogenic variations in various genes that function in cell growth and proliferation. This study aimed to describe the germline variations in patients with hereditary cancer using multigene panels. Methods: The molecular and clinical findings of 218 patients with HCS were evaluated. In addition, 25 HCS-related genes were sequenced using a multigene panel, and variations were classified according to the American College of Medical Genetics and Genomics (ACMG) criteria. In total, 218 HCS patients predominantly with breast, colorectal, ovarian, gastric, and endometrium cancers were included. Results: Pathogenic variations in 12 distinct genes were detected in 36 of 218 (16.5%) cases. In this study, the most affected gene was the ATM gene, in which pathogenic variations were detected in 8 of 218 cases, followed by CHEK2 (3.2%), MUTYH (3.2%), BRIP1 (1.8%), BARD1 (0.9%), TP53 (0.9%), PALB2 (0.4%), MLH1 (0.4%), MSH2 (0.4%), PMS2 (0.4%), RAD50 (0.4%), and RAD51C (0.4%). Conclusions: This study contributes to genotype-phenotype correlation in HCSs and expands the variation spectrum by introducing three novel pathogenic variations. The wide spectrum of the gene pathogenic variations detected and the presence of multiple gene defects in the same patient make the multigene panel testing a valuable tool in detecting the hereditary forms of cancer and providing effective genetic counseling and family specific screening strategies.Amaç: Herediter kanser sendromları (HCS) hücre büyümesi ve proliferasyonunda görevli genlerde saptanan germline mutasyonlardan kaynaklanan heterojen bir grup hastalıktır. Bu çalışmada kalıtımsal kanser sendrom ön tanısıyla değerlendirilen olgularda çoklu gen paneli ile germ hattı varyasyonlarının değerlendirilmesi planlanmıştır. Yöntemler: Kalıtımsal kanser sendromu düşünülen 218 olgudan periferik kandan DNA izolasyonu sonrası HCS ile ilişkili 25 gen multigen panel kullanılarak dizilendi ve varyasyonlar American College of Medical Genetics and Genomics (ACMG) kriterlerine göre değerlendirildi. Bulgular: Meme, kolorektal, over, gastrik ve endometriyum kanseri başta olmak üzere toplam 218 herediter kanser sendromlu olgu değerlendirildi. Tüm çalışma grubu incelendiğinde en sık ATM gen varyasyonları (8/218, %3,6) tespit edildi ve bunu sıklık sırasına göre CHEK2 (%3,2), MUTYH (%3,2), BRIP1 (%1,8), BARD1 (%0,9), TP53 (%0,9), PALB2 (%0,4), MLH1 (%0,4), MSH2 (%0,4), PMS2 (%0,4), RAD50 (%0,4), RAD51C (%0,4) varyasyonları takip etmekteydi. Sonuçlar: Bu çalışmada farklı kanser türlerinde kalıtımsal kansere yol açan genler analiz edilmiş ve fenotiple ilişkisi değerlendirilmiştir. Ayrıca bu çalışmada ilk kez saptanan üç yeni varyasyon ile literatüre katkı sağlanmaktadır. Patojenik varyasyon tespit edilen genlerin geniş dağılımı ve aynı hastada birden fazla genetik varyasyonun varlığı düşünüldüğünde, uygun genetik danışma ve aileye özgü tarama planlaması yapmak için çoklu gen taraması kalıtımsal kanser hastalarının değerlendirilmesinde hızlı ve etkin bir yöntem olarak görünmektedir

The Spectrum of Low-Density Lipoprotein Receptor Mutations in a Large Turkish Cohort of Patients with Familial Hypercholesterolemia

Background: Monogenic hypercholesterolemia with Mendelian inheritance is a heterogeneous group of diseases that are characterized by elevated plasma low-density lipoprotein cholesterol (LDL-C) levels, and the most common form of this disorder is autosomal-dominant familial hypercholesterolemia (FH). Methods: A total of 104 index cases with the clinical diagnosis of FH were included in this study. Low-density lipoprotein receptor (LDLR) was sequenced using the Sanger sequencing method. Results: Pathogenic/likely pathogenic variants were detected in LDLR in 55 of the 104 cases (mutation detection rate = 52.8%). Thirty different variants were detected in LDLR, three of which were novel. The total cholesterol and LDL-C values of the patients in the group of premature termination codon (PTC) mutation carriers were significantly higher than those of the patients in the group of non-PTC mutation carriers. A total of 87 patients (17 pediatric and 70 adult cases) were diagnosed with cascade genetic screening. Statin treatment was recommended to all 87 patients and was accepted and initiated in 70 of these patients. Conclusions: This study is the largest patient cohort that evaluated FH cases in the Turkish population. Herein, we revealed the LDLR mutation spectrum for a Turkish population and compared the cases in the context of genotype-phenotype correlation. Genetic screening of individuals with suspected FH not only helps to establish their diagnosis, but also facilitates early diagnosis and treatment initiation in other family members through cascade screening

Meckel-Gruber Syndrome: Clinical and Molecular Genetic Profiles in Two Fetuses and Review of the Current Literature

Background: Meckel-Gruber syndrome (MKS; OMIM No. 249000) is a rare, in utero lethal disease characterized by occipital encephalocele, polycystic kidneys, and polydactyly. Methodology and Results: In this study, two fetuses diagnosed as having MKS in the prenatal period were evaluated on the basis of ultrasonographic findings, postmortem autopsy findings, and molecular genetic analyses. Using exome sequencing analyses a novel homozygous frameshift variant (NM_015631: c.530delA, p.Lys177Argfs*47) was detected at exon 4 of TCTN3 gene in case 1, and a novel homozygous synonymous variant (NM_025114: c.180G>A, p Lys60Lys) was detected at exon 3 of CEP290 gene in case 2. Case 1 is the first reported case in the literature, which showed the typical MKS clinical feature with a novel frameshift variation in the TCTN3 gene. The variant in case 2 is the first reported synonymous variant of CEP290 gene in the literature, which has been shown to affect splicing in a functional study at the RNA level. Conclusion: TCTN3 gene variants that were rarely associated with the typical MKS phenotype and all cases with these variations have been discussed in the context of genotype-phenotype. The detection of the first synonymous variant of CEP290 gene and the demonstration of its effect on splicing by a functional study are likely to contribute to the molecular etiology of MKS

Enostosis in a patient with KBG syndrome caused by a novel missense ANKRD11 variant

KBG syndrome (KBGS-OMIM:#148050) is a rare autosomal dominant disease characterized by short stature, intellectual disability, characteristic facies, skeletal anomalies and macrodontia that most commonly affect the permanent upper central incisors. In 2011, Sirmaci et al. (2011) identified heterozygous loss-of-function variants in the ANKRD11 gene on chromosome 16q24.3. So far, more than 150 patients have been reported in the literature. ANKRD11 gene encodes ankyrin repeat domain-containing protein 11 that regulates transcriptional activation (Zhang et al., 2004). Apart from single-nucleotide variations in the ANKRD11 gene, copy number variations on chromosome 16q24.3 can also cause KBG syndrome-like phenotype. In this study, we present a patient with de-novo novel missense variant in ANKRD11 gene. We have also identified skeletal bone enostosis as an additional finding, which is not previously reported

Differential diagnosis of classical Bartter syndrome and Gitelman syndrome: Do we need genetic analysis?

Objective: Classical Bartter syndrome (cBS) and Gitelman syndrome (GS) are genotypically distinct, but there is a phenotypic overlap among these two diseases, which can complicate the accurate diagnosis without genetic analysis. This study aimed to evaluate the correlation between clinical and genetic diagnoses among patients who have genetically defined cBS and GS. Patients and Methods: The study included 18 patients with homozygous/compound heterozygous CLCNKB (NM_000085) (n:10/18) and SLC12A3 (NM_000339) (n:8/18) mutations. Biochemical, clinical and radiological data were collected at presentation and at the last visit. Results: In cBS group age at diagnosis, median plasma potassium and chloride concentrations were significantly lower and median plasma HCO3 and blood pH values were significantly higher. Patients with GS had significantly lower median plasma magnesium concentrations and urinary calcium/creatinine ratio. One child with GS had normocalciuria, two children with cBS had hypocalciuria and hypomagnesemia. Low estimated glomerular filtration rate (eGFR) (ml/dk/1.73m2) and growth failure were more evident in cBS group. In patients with cBS, nine different CLCNKB gene mutations were detected, five of them were novel. Novel mutations were: one nonsense (c.66G>A, p.Trp22*), one missense (c.499G>A, p.Gly167Ser) and three splice-site (c.867-2delA; c.499-2insG; c.19302A>C) mutations. In patients with GS, six different SLC12A3 gene mutations were found. Conclusions: It may not always be possible to clinically distinguish cBS from GS. We suggest to perform a genotypic classification if genetic analysis is possible

Biallelic Mutations in DNAJB11are Associated with Prenatal Polycystic Kidney Disease in a Turkish Family

Polycystic kidney disease (PKD) is a life-threatening condition resulting in end-stage renal disease. Two major forms of PKD are defined according to the inheritance pattern. Autosomal dominant PKD (ADPKD) is characterized by renal cysts, where nearly half of the patients suffers from renal failure in the 7th decade of life. Autosomal recessive PKD (ARPKD) is a rarer and more severe form presenting in childhood. Whole-exome sequencing (WES) analyses was performed to investigate molecular causes of the disease in the fetus. In this study, we present 2 fetuses prenatally diagnosed with PKD in a consanguineous family. WES analysis of the second fetus revealed a homozygous variant (c.740+1G>A) in DNAJB11 which is related to ADPKD. This study reveals that DNAJB11 biallelic mutations may cause an antenatal severe form of ARPKD and contributes to understanding the DNAJB11-related ADPKD phenotype. The possibility of ARPKD due to biallelic mutations in ADPKD genes should be considered in genetic counseling

The use of long-range pcr protocol in the diagnosis of friedreich ataxia

Introduction: Friedreich ataxia(FRDA) is multisystemic disorder characterized by trinucleotide expansions in FXN gene. It’s one of the most common causes of autosomal recessive ataxia. Material/Method: Fragment analysis method was used to detect GAA triple nucleotide repeat expansions in the first intron of the FXN gene. Long-range PCR was performed with primers selected from both in intron and exon for confirmation in patients with more than two hundred repeats. Results: Fragment analysis was performed in 20 patients with FRDA pre-diagnosis. Long-range PCR was performed in 5 patients with more than 200 GAA repeats. After long-range PCR, the number of repetitions between 180 and 1450 was found in these patients. One allele of two siblings whose fragment analysis gave negative results was found to have an approximately 950 repeats. FXN gene sequence analysis was planned in order not to miss point mutations in patients with negative results. In order to provide appropriate genetic counseling to patients, segregation studies are continuing. Discussion: Although fragment analysis is reliable method in this disease, its reliability decreases when the number of repeats is high. Although Southern-blot method can be used for confirmation, long-range PCR protocols which are cheaper and easier, can also be applied