The long Filamin-A isoform is required for intestinal development and motility: implications for chronic intestinal pseudo-obstruction.

Filamin A (FLNA) is a cytoplasmic actin binding protein, recently shown to be expressed as a long and short isoform. Mutations in FLNA are associated with a wide spectrum of disorders, including an X-linked form of chronic intestinal pseudo-obstruction (CIPO). However, the role of FLNA in intestinal development and function is largely unknown. In this study, we show that FLNA is expressed in the muscle layer of the small intestine from early human fetal stages. Expression of FLNA variants associated with CIPO, blocked expression of the long flna isoform and led to an overall reduction of RNA and protein levels. As a consequence, contractility of human intestinal smooth muscle cells was affected. Lastly, our transgenic zebrafish line showed that the flna long isoform is required for intestinal elongation and peristalsis. Histological analysis revealed structural and architectural changes in the intestinal smooth muscle of homozygous fish, likely triggered by the abnormal expression of intestinal smooth muscle markers. No defect in the localization or numbers of enteric neurons was observed. Taken together, our study demonstrates that the long FLNA isoform contributes to intestinal development and function. Since loss of the long FLNA isoform does not seem to affect the enteric nervous system, it likely results in a myopathic form of CIPO, bringing new insights to disease pathogenesis.

TFAP2B Haploinsufficiency Impacts Gastrointestinal Function and Leads to Pediatric Intestinal Pseudo-obstruction.

Background: Pediatric Intestinal Pseudo-obstruction (PIPO) is a congenital enteric disorder characterized by severe gastrointestinal (GI) dysmotility, without mechanical obstruction. Although several genes have been described to cause this disease, most patients do not receive a genetic diagnosis. Here, we aim to identify the genetic cause of PIPO in a patient diagnosed with severe intestinal dysmotility shortly after birth. Methods: Whole exome sequencing (WES) was performed in the patient and unaffected parents, in a diagnostic setting. After identification of the potential disease-causing variant, its functional consequences were determined in vitro and in vivo. For this, expression constructs with and without the causing variant, were overexpressed in HEK293 cells. To investigate the role of the candidate gene in GI development and function, a zebrafish model was generated where its expression was disrupted using CRISPR/Cas9 editing. Results: WES analysis identified a de novo heterozygous deletion in TFAP2B (NM_003221.4:c.602-5_606delTCTAGTTCCA), classified as a variant of unknown significance. In vitro studies showed that this deletion affects RNA splicing and results in loss of exon 4, leading to the appearance of a premature stop codon and absence of TFAP2B protein. Disruption of tfap2b in zebrafish led to decreased enteric neuronal numbers and delayed transit time. However, no defects in neuronal differentiation were detected. tfap2b crispants also showed decreased levels of ednrbb mRNA, a downstream target of tfap2b. Conclusion: We showed that TFAP2B haploinsufficiency leads to reduced neuronal numbers and GI dysmotility, suggesting for the first time, that this gene is involved in PIPO pathogenesis.

Optimization of DNA isolation method from Formalin-Fixed-Paraffin-Embedded tissues (FFPE) and comparative performance of four different Polymerase Chain Reaction (PCR) kits.

The tissue sample may have important genetic information in diagnostic, prognostic and counselling issues. Formalin-Fixed-Paraffin-Embedded (FFPE) is a routine method for preserving tissues. However, DNA isolated from FFPE tissue is often difficult to be amplified in PCR due to fragmentation and DNA-protein crosslinks. This study aimed to optimize the DNA isolation method from FFPE tissue and compare the performance of four different PCR ready-to-use kits. Genomic DNA was isolated from FFPE tissue colon of Short-segment Hirschsprung (S-HSCR) patients and prostate cancer tissue using Quick-DNA™ FFPE Kit (Zymo Research) with and without pre-heating treatment in KOH/NOH solution. Primers for Androgen Receptor (AR) gene and four different PCR kits: MyTaq HS Red Mix 2X (BioLine), FastStart Taq DNA Polymerase (Roche), KAPA2G fast PCR Kit 2X (KAPA Biosystem) and KOD FX Neo (Toyobo) were used for amplification. DNA electrophoresis was performed to compare the PCR results. BioLine and Toyobo kits gave better PCR results than those of Roche and KAPA Biosystem. Increasing amount of Taq polymerase and dNTPs of Roche kit by two-fold could increase the quality of PCR results. Toyobo could amplify DNA up to 417 bp, however, none of these PCR kits could amplify DNA above 450 bp. Pre-heated treatment of FFPE tissue in NaOH/KOH did not improve the DNA quality and PCR results. Toyobo PCR ready-to-use kit gave the best result among the other three PCR kits used in this study in amplifying DNA isolated from FFPE tissue. Designing the primers producing amplicon not more than 450 bp is suggested.

A novel de novo mutation in Lamin A/C gene in Emery Dreifuss Muscular Dystrophy patient with atrial paralysis.

We present a 26 year old female Indonesian patient with full spectrum Emery Dreifuss Muscular Dystrophy (EDMD) characterized with contracture of elbows, heel cord and pelvic muscle wasting and weakness and atrial paralysis, as rare cardiac findings in EDMD . A novel de novo pathogenic heterozygous missense mutation (NM_170707.3: c.122G>T, p.Arg41Leu) in exon 1 was detected. Preventing atrial paralytic patients from systemic embolism is important. Early diagnosis, intervention, targeted management and counseling are necessary for a better health and life quality of individuals with EDMD.

Mutation spectrum of ß-globin gene in thalassemia patients at Hasan Sadikin Hospital - West Java Indonesia.

Thalassemia is the most common hereditary haemolytic anemia in Southeast Asia, in which Indonesia is among countries that are at a high risk for thalassemia. It has been reported that mutation in the beta-globin gene is responsible in severe Thalassemia. However, the spectrum of beta-globin gene mutations in Indonesian population varies in different regions . Thus, this study aimed to identify the most prevalent mutation of Thalassemia patients from the Hasan Sadikin Hospital, Bandung, using this as a reference hospital for Thalassemia in West Java. The three most prevalent mutations of beta globin (IVS1nt5, Cd26 (HbE), and IVS1nt1), were conducted in the beginning of this study. Mutations of 291 samples were detected by PCR-RFLP in the Molecular Genetic Laboratory, Faculty of Medicine Universitas Padjadjaran, Bandung. The prevalence of the beta globin gene mutation types were 47.4% IVS1nt5 homozygote, 9.9% compound heterozygote IVS1nt5/HbE, 5.4% compound heterozygote IVS1nt5/IVS1nt1, 1.4% compound heterozygote HbE/IVS1nt1, 1% HbE homozygote, 14.4% Compound heterzygote IVS1nt5/… (no paired mutation), 2.06% compound heterozygote HbE/… (no paired mutation), 1.3% compound heterozygote IVS1nt1/… (no paired mutation), and 7 samples were unidentified. The thalassemia mutation IVS1nt5 homozygote is the most common mutation found in Thalassemia patients at Hasan Sadikin Hospital, Bandung. The samples with unidentified results might carry mutations other than the three that are observed in the present study.

A Rare, Recurrent, De Novo 14q32.2q32.31 Microdeletion of 1.1 Mb in a 20-Year-Old Female Patient with a Maternal UPD(14)-Like Phenotype and Intellectual Disability.

We present a 20-year-old female patient from Indonesia with intellectual disability (ID), proportionate short stature, motor delay, feeding problems, microcephaly, facial dysmorphism, and precocious puberty who was previously screened normal for conventional karyotyping, fragile X testing, and subtelomeric MLPA analysis. Subsequent genome wide array analysis was performed on DNA from blood and revealed a 1.1 Mb deletion in 14q32.2q32.31 (chr14:100,388,343-101,506,214; hg19). Subsequent carrier testing in the parents by array showed that the deletion had occurred de novo in the patient and that her paternal 14q32 allele was deleted. The deleted region encompasses the DLK1/GTL2 imprinted gene cluster which is consistent with the maternal UPD(14)-like phenotype of the patient. This rare, recurrent microdeletion was recently shown not to be mediated by low copy repeats, but by expanded TGG repeats, flanking the 14q32.2q32.21 deletion boundaries, a novel mechanism of recurrent genomic rearrangement. This is another example how the application of high resolution genome wide testing provides an accurate genetic diagnosis, thereby improving the care for patients and optimizing the counselling for family.