A novel KIF11 mutation in a Turkish patient with microcephaly, lymphedema, and chorioretinal dysplasia from a consanguineous family.

Microcephaly–lymphedema–chorioretinal dysplasia (MLCRD) syndrome is a rare syndrome that was first described in 1992. Characteristic craniofacial features include severe microcephaly, upslanting palpebral fissures, prominent ears, a broad nose, and a long philtrum with a pointed chin. Recently, mutations in KIF11 have been demonstrated to cause dominantly inherited MLCRD syndrome. Herein, we present a patient with MLCRD syndrome whose parents were first cousins. The parents are unaffected, and thus a recessive mode of inheritance for the disorder was considered likely. However, the propositus carries a novel, de novo nonsense mutationinexon2 of KIF11. The patient also had midline cleft tongue which has not previously been described in this syndrome

Molecular Genetic Analysis of Survival Motor Neuron Gene in 460 Turkish Cases with Suspicious Spinal Muscular Atrophy Disease

How to Cite This Article: Rashnonejad A, Onay H, Atik T, Atan Sahin O, Gokben S, Tekgul H, Ozkinay F. Molecular Genetic Analysis of Survival Motor Neuron Gene in 460 Turkish Cases with Suspicious Spinal Muscular Atrophy Disease. Iran J Child Neurol. Autumn 2016; 10(4):30-35.AbstractObjectiveTo describe 12 yr experience of molecular genetic diagnosis of Spinal Muscular Atrophy (SMA) in 460 cases of Turkish patients. Materials & MethodsA retrospective analysis was performed on data from 460 cases, referred to Medical Genetics Laboratory, Ege University’s Hospital, Izmir, Turkey, prediagnosed as SMA or with family history of SMA between 2003 and 2014.The PCR-restriction fragment length polymorphism (RFLP) and the Multiplex ligation–dependent probe amplification (MLPA) analysis were performed to detect the survival motor neuron (SMN)1 deletions and to estimate SMN1 and SMN2 gene copy numbers. ResultsUsing PCR-RFLP test, 159 of 324 postnatal and 18 of 77 prenatal cases were detected to have SMN1 deletions. From positive samples, 88.13% had a homozygous deletion in both exon 7 and exon 8 of SMN1. Using MLPA, 54.5% of families revealed heterozygous deletions of SMN1, and 2 or 3 copies of SMN2, suggesting a healthy SMA carrier. Among patients referred for SMA testing, the annual percentage of patients diagnosed as SMA has decreased gradually from 90.62% (2003) down to 20.83% (2014). ConclusionAlthough PCR-RFLP method is a reliable test for SMA screening, MLPA is a necessary additional test and provide relevant data for genetic counseling of families having previously affected child. The gradual decrease in the percentage of patients molecularly diagnosed as SMA shows that clinicians have begun to use genetic tests in the differential diagnosis of muscular atrophies. Cost and availability of these genetic tests has greatly attributed to their use.   References1. Brichta L, Holker I, Haug K, Klockgether T, Wirth B. In vivo activation of SMN in spinal muscular atrophy carriers and patients treated with valprotae. Ann Neurol 2006;59:970-5.2. Prior TW, Krainer AR, Hua Y, Swoboda KJ, Snyder PC, Bridgeman SJ, et al. A positive modifier of spinal muscular atrophy in the SMN2 gene. Am J Hum Genet 2009;85:408-13.3. Striano P, Boccella P, Sarappa C, Striano S. Spinal muscular atrophy and progressive myoclonic epilepsy: one case report and characteristics of the epileptic syndrome. Seizure 2004;13:582-6.4. Wirth B. An update of the mutation spectrum of the survival motor neuron gene (SMN1) in autosomal recessive spinal muscular atrophy (SMA). Hum Mutat 2000;15:228-37.5. Van der Steege G, Grootscholten PM, Van der Vlies P, Draaijers TG, Osinga J, Cobben JM, et al. PCR-based DNA test to confirm clinical diagnosis of autosomal recessive spinal muscular atrophy. Lancet 1995;345:985-6.6. Rekik I, Boukhris A, Ketata S, Amri M, Essid N, Feki I, et al. Deletion analysis of SMN and NAIP genes in Tunisian patients with spinal muscular atrophy. Ann Indian Acad Neurol 2013;16:57-61.7. de Souza Godinho FM, Bock H, Gheno TC, Saraiva-Pereira ML. Molecular Analysis of Spinal Muscular Atrophy: A genotyping protocol based on TaqMan realtime PCR. Genet Mol Biol 2012;35:955-9.8. Burghes AH. When deletion is not a deletion? When it is converted? Am J Hum Genet 1997;61:9-15.9. Kubo Y, Nishio H, Saito K. A new method for SMN1 and hybrid SMN gene analysis 1. in spinal muscular atrophy using long-range PCR followed by sequencing. J Hum 2. Genet 2015;60:233-9.10. Ogino S, Leonard DG, Rennert H, Wilson RB. Spinal Muscular Atrophy Genetic Testing Experience at an Academic Medical Center. J Mol Diagn 2002;4:53-8.11. Baumbach-Reardon L, Sacharow S, Ahearn ME. Spinal Muscular Atrophy, X-Linked Infantile. Gene Review 1993.12. Khaniani MS, Derakhshan SM, Abasalizadeh S. Prenatal diagnosis of spinal muscular atrophy: clinical experience and molecular genetics of SMN gene analysis in 36 cases. J Prenat Med 2013;7:32-4.13. Lin SP, Chang JG, Jong YJ, Yang TY, Tsai CH, Wang NM, et al. Prenatal prediction of spinal muscular atrophy in Chinese. Prenat Diagn 1999;19:657-61.14. Cobben JM, Scheffer H, De visser M, Van der Steege G, Verhey JB, Osigna J, et al. Prenatal prediction of spinal muscular atrophy. Experience with linkage studies and consequences of present SMN deletion analysis. Eur J Hum Genet 1996;4:231-6.15. Miskovic M, Lalic T, Radivojevic D, Cirkovic S, Ostojic S, Guc-Scekic M. Ten years of experience in molecular prenatal diagnosis and carrier testing for spinal muscular atrophy among families from Serbia. Int J Gynaecol Obstet 2014;124:55-8.16. Mailman MD, Heinz JW, Papp AC, Snyder PJ, Sedra MS, Burghes AHM, Wirth B, Prior TW. Molecular analysis of spinal muscular atrophy and modification of the phenotype by SMN2. Genet Med 2002;4:20–26.17. Ogino S, Leonard DG, Rennert H, Ewens WJ, Wilson RB. Genetic risk assessment in carrier testing for spinal muscular atrophy. Am J Med Genet 2002;110:301-7.18. Wirth B. An update on the mutation spectrum of the survival motor neuron gene (SMN1) in autosomal recessive spinal muscular atrophy (SMA). Hum Mutat 2000;15:228–37

Biallelic variants in ADAMTS15 cause a novel form of distal arthrogryposis

Purpose We aimed to identify the underlying genetic cause for a novel form of distal arthrogryposis. Methods Rare variant family-based genomics, exome sequencing, and disease-specific panel sequencing were used to detect ADAMTS15 variants in affected individuals. Adamts15 expression was analyzed at the single-cell level during murine embryogenesis. Expression patterns were characterized using in situ hybridization and RNAscope. Results We identified homozygous rare variant alleles of ADAMTS15 in 5 affected individuals from 4 unrelated consanguineous families presenting with congenital flexion contractures of the interphalangeal joints and hypoplastic or absent palmar creases. Radiographic investigations showed physiological interphalangeal joint morphology. Additional features included knee, Achilles tendon, and toe contractures, spinal stiffness, scoliosis, and orthodontic abnormalities. Analysis of mouse whole-embryo single-cell sequencing data revealed a tightly regulated Adamts15 expression in the limb mesenchyme between embryonic stages E11.5 and E15.0. A perimuscular and peritendinous expression was evident in in situ hybridization in the developing mouse limb. In accordance, RNAscope analysis detected a significant coexpression with Osr1, but not with markers for skeletal muscle or joint formation. Conclusion In aggregate, our findings provide evidence that rare biallelic recessive trait variants in ADAMTS15 cause a novel autosomal recessive connective tissue disorder, resulting in a distal arthrogryposis syndrome

Using mouse and zebrafish models to understand the etiology of developmental defects in Cornelia de Lange Syndrome

Cornelia de Lange Syndrome (CdLS) is a multisystem birth defects disorder that affects every tissue and organ system in the body. Understanding the factors that contribute to the origins, prevalence, and severity of these developmental defects provides the most direct approach for developing screens and potential treatments for individuals with CdLS. Since the majority of cases of CdLS are caused by haploinsufficiency for NIPBL (Nipped-B-like, which encodes a cohesin-associated protein), we have developed mouse and zebrafish models of CdLS by using molecular genetic tools to create Nipbl-deficient mice and zebrafish (Nipbl(+/−) mice, zebrafish nipbl morphants). Studies of these vertebrate animal models have yielded novel insights into the developmental etiology and genes/gene pathways that contribute to CdLS-associated birth defects, particularly defects of the gut, heart, craniofacial structures, nervous system, and limbs. Studies of these mouse and zebrafish CdLS models have helped clarify how deficiency for NIPBL, a protein that associates with cohesin and other transcriptional regulators in the nucleus, affects processes important to the emergence of the structural and physiological birth defects observed in CdLS: NIPBL exerts chromosome position-specific effects on gene expression; it influences long-range interactions between different regulatory elements of genes; and it regulates combinatorial and synergistic actions of genes in developing tissues. Our current understanding is that CdLS should be considered as not only a cohesinopathy, but also a “transcriptomopathy,” that is, a disease whose underlying etiology is the global dysregulation of gene expression throughout the organism

Loss of the BMP Antagonist, SMOC-1, Causes Ophthalmo-Acromelic (Waardenburg Anophthalmia) Syndrome in Humans and Mice

Ophthalmo-acromelic syndrome (OAS), also known as Waardenburg Anophthalmia syndrome, is defined by the combination of eye malformations, most commonly bilateral anophthalmia, with post-axial oligosyndactyly. Homozygosity mapping and subsequent targeted mutation analysis of a locus on 14q24.2 identified homozygous mutations in SMOC1 (SPARC-related modular calcium binding 1) in eight unrelated families. Four of these mutations are nonsense, two frame-shift, and two missense. The missense mutations are both in the second Thyroglobulin Type-1 (Tg1) domain of the protein. The orthologous gene in the mouse, Smoc1, shows site- and stage-specific expression during eye, limb, craniofacial, and somite development. We also report a targeted pre-conditional gene-trap mutation of Smoc1 (Smoc1tm1a) that reduces mRNA to ∼10% of wild-type levels. This gene-trap results in highly penetrant hindlimb post-axial oligosyndactyly in homozygous mutant animals (Smoc1tm1a/tm1a). Eye malformations, most commonly coloboma, and cleft palate occur in a significant proportion of Smoc1tm1a/tm1a embryos and pups. Thus partial loss of Smoc-1 results in a convincing phenocopy of the human disease. SMOC-1 is one of the two mammalian paralogs of Drosophila Pentagone, an inhibitor of decapentaplegic. The orthologous gene in Xenopus laevis, Smoc-1, also functions as a Bone Morphogenic Protein (BMP) antagonist in early embryogenesis. Loss of BMP antagonism during mammalian development provides a plausible explanation for both the limb and eye phenotype in humans and mice

Multiple Organ System Defects and Transcriptional Dysregulation in the Nipbl+/− Mouse, a Model of Cornelia de Lange Syndrome

Cornelia de Lange Syndrome (CdLS) is a multi-organ system birth defects disorder linked, in at least half of cases, to heterozygous mutations in the NIPBL gene. In animals and fungi, orthologs of NIPBL regulate cohesin, a complex of proteins that is essential for chromosome cohesion and is also implicated in DNA repair and transcriptional regulation. Mice heterozygous for a gene-trap mutation in Nipbl were produced and exhibited defects characteristic of CdLS, including small size, craniofacial anomalies, microbrachycephaly, heart defects, hearing abnormalities, delayed bone maturation, reduced body fat, behavioral disturbances, and high mortality (75–80%) during the first weeks of life. These phenotypes arose despite a decrease in Nipbl transcript levels of only ∼30%, implying extreme sensitivity of development to small changes in Nipbl activity. Gene expression profiling demonstrated that Nipbl deficiency leads to modest but significant transcriptional dysregulation of many genes. Expression changes at the protocadherin beta (Pcdhb) locus, as well as at other loci, support the view that NIPBL influences long-range chromosomal regulatory interactions. In addition, evidence is presented that reduced expression of genes involved in adipogenic differentiation may underlie the low amounts of body fat observed both in Nipbl+/− mice and in individuals with CdLS