Bloom's syndrome in a 12-year-old Iranian girl

Background: Bloom\u2032s syndrome, an autosomal recessive inherited disorder, belongs to the group of chromosomal breakage syndromes. The clinical diagnosis of BS is confirmed cytogenetically. Its frequency in the general population is unknown but it is common in eastern European Ashkenazi Jews . Case Report: A 12-year-old girl was referred to us because of short stature. She was the second child of the first cousin marriage. She had a slender body frame, short stature, and microcephaly. Her face was long and narrow with prominent nose, and malar and mandibular hypoplasia. The spots of hyper and hypo pigmentation were observed in the trunk and limbs. Telangectasia spots were observed in some areas of the trunk. Additionally, generalized hirsutism was present in the whole body. Cytogenetic findings revealed an abnormality in the structural chromosome. Conclusion: This is the first BS case that has been reported in Iranian female population

array CGH screening of 134 unrelated families

Background A growing number of non-coding regulatory mutations are being identified in congenital disease. Very recently also some exons of protein coding genes have been identified to act as tissue specific enhancer elements and were therefore termed exonic enhancers or “eExons”. Methods We screened a cohort of 134 unrelated families with split-hand/split-foot malformation (SHFM) with high resolution array CGH for CNVs with regulatory potential. Results In three families with an autosomal dominant non-syndromic SHFM phenotype we detected microdeletions encompassing the exonic enhancer (eExons) 15 and 17 of DYNC1I1. In a fourth family, who had hearing loss in addition to SHFM, we found a larger deletion of 510 kb including the eExons of DYNC1I1 and, in addition, the human brain enhancer hs1642. Exons 15 and 17 of DYNC1I1 are known to act as tissue specific limb enhancers of DLX5/6, two genes that have been shown to be associated with SHFM in mice. In our cohort of 134 unrelated families with SHFM, deletions of the eExons of DYNC1I1 account for approximately 3% of the cases, while 17p13.3 duplications were identified in 13% of the families, 10q24 duplications in 12%, and TP63 mutations were detected in 4%. Conclusions We reduce the minimal critical region for SHFM1 to 78 kb. Hearing loss, however, appears to be associated with deletions of a more telomeric region encompassing the brain enhancer element hs1642. Thus, SHFM1 as well as hearing loss at the same locus are caused by deletion of regulatory elements. Deletions of the exons with regulatory potential of DYNC1I1 are an example of the emerging role of exonic enhancer elements and their implications in congenital malformation syndromes

Targeted Next-Generation Sequencing of a Deafness Gene Panel (MiamiOtoGenes) Analysis in Families Unsuitable for Linkage Analysis

Hearing loss (HL) is a common sensory disorder in humans with high genetic heterogeneity. To date, over 145 loci have been identified to cause nonsyndromic deafness. Furthermore, there are countless families unsuitable for the conventional linkage analysis. In the present study, we used a custom capture panel (MiamiOtoGenes) to target sequence 180 deafness-associated genes in 5 GJB2 negative deaf probands with autosomal recessive nonsyndromic HL from Iran. In these 5 families, we detected one reported and six novel mutations in 5 different deafness autosomal recessive (DFNB) genes (TRIOBP, LHFPL5, CDH23, PCDH15, and MYO7A). The custom capture panel in our study provided an efficient and comprehensive diagnosis for known deafness genes in small families

Identification of splice defects due to noncanonical splice site or deep‐intronic variants in ABCA4

Pathogenic variants in the ATP-binding cassette transporter A4 (ABCA4) gene cause a continuum of retinal disease phenotypes, including Stargardt disease. Noncanonical splice site (NCSS) and deep-intronic variants constitute a large fraction of disease-causing alleles, defining the functional consequences of which remains a challenge. We aimed to determine the effect on splicing of nine previously reported or unpublished NCSS variants, one near exon splice variant and nine deep-intronic variants in ABCA4, using in vitro splice assays in human embryonic kidney 293T cells. Reverse transcription-polymerase chain reaction and Sanger sequence analysis revealed splicing defects for 12 out of 19 variants. Four deep-intronic variants create pseudoexons or elongate the upstream exon. Furthermore, eight NCSS variants cause a partial deletion or skipping of one or more exons in messenger RNAs. Among the 12 variants, nine lead to premature stop codons and predicted truncated ABCA4 proteins. At least two deep-intronic variants affect splice enhancer and silencer motifs and, therefore, these conserved sequences should be carefully evaluated when predicting the outcome of NCSS and deep-intronic variants

Hochdurchsatz -Technologien, die molekulare Basis von angeborenen Gliedmaßenfehlbildungen untersuchen

Genomic alterations, such as point mutations and structural variations are known causes of congenital limb defects in human. The genetic heterogeneity underlying these anomalies requires a genome-wide diagnostic approach. In this thesis we applied the whole exome sequencing (WES) and microarray-based comparative genomic hybridization (array CGH) techniques in a group of patients presenting with different types of limb malformations. The first part of the thesis concerns investigating a missense mutation and a deletion within the Sterile Alpha Motif (SAM) domain of the ZAK gene, that were identified in Pakistani and Tunisian families, respectively. All the affected family members in both pedigrees were presenting with split foot malformation, hearing impairment and nail deformity. We applied the CRISPR/Cas9 system in the mouse embryonic stem cells to generate a ZAK mouse model deficient in the SAM- containing domain of the gene. The obtained mutant showed a complex limb duplication defect. The abnormality was induced by the downregulation on the Tp63 gene. Also, we showed that the ZAK gene was expressed in the heart and limbs in mice and the knockout of both ZAK isoforms via CRISPR/Cas9 genome editing was lethal in transgenic mice. The next section of the thesis concerns an Iranian patient presenting with a severe metacarpal-to-carpal transformation that was subjected to the whole exome sequencing. The patient’s parents were consanguineous and not affected, which strongly indicated to a recessive mode of inheritance. WES analysis revealed a novel homozygous missense mutation c.938C>G (p.313T>R) in the HOXD13 gene. We showed using electrophoretic mobility shift assay (EMSA) that this substitution led to the HOXD13 protein loss of function. The last chapter concerns a cohort of patients presenting with ectrodactyly. In this part, 134 families were subjected to array CGH. Heterozygous microdeletions encompassing two exons of the DYNC1I1 gene, which normally functions as a limb enhancer of the Dlx5/6 genes, on chromosome 7q21.3 were identified. Based on the research described in this thesis we can conclude: 1) the crucial role of ZAK gene in limb deformities, 2) the causative character of the homozygous point mutation in the HOXD13 gene identified in a patient presenting with a severe limb defect, whose healthy parents were carriers of the mutation, 3) the substantial role of deletions in coding extremities enhancer of Dlx5/6 gene on chromosome 7q21.3, which were found in about 3% of all families with limb malformations.Genetische Veränderungen, wie Punkmutationen und Strukturvarianten, sind als Ursache für angeborene Defekte der Gliedmaßen im Menschen bekannt. Da es sich um ein phänotypisch und genotypisch sehr heterogenes Krankheitsbild handelt, ist es sinnvoll diese Fälle mit genomweiten Analyseverfahren wir der Microarray-basierten komparativen genomischen Hybridisierung (Array CGH) und mittels Exome Sequenzierung zu untersuchen. Im ersten Teil dieser Arbeit habe, habe ich eine homozygote Missens-Mutation und eine überlappende homozygote Deletion in der Sterile Alpha Motif (SAM) Domäne des ZAK Gens identifiziert in einer pakistanischen und einer tunesischen Familie. Beide Familien zeigten Spaltfüße, Nagelverdopplung der Hände und Schwerhörigkeit. Wir konnten mittels in situ Hybridisierung zeigen, dass in der Maus ZAK im embryonalen Herzen und in den Extremitäten exprimieret ist. Der komplette knock out von beiden Isoformen von ZAK mittels CRISPR/Cas genome editing zeigte sich als früh embryonal letal. Die spezifische Deletion der SAM Domäne des ZAK Gens zeigte einen Duplikationsdefekt der Extremitäten, welcher mit einer verminderten Tp63 Expression einherging. Im zweiten Teil der Arbeit habe ich eine Familie aus dem Iran mit einer schweren Form der Synpolydaktylie mittels Exome Sequenzierung untersucht. Wir konnten erstmals eine homozygote Missens- Mutation im HOXD13 Gen als ursächlich für eine schwere Synpolydaktylie nachweisen. Mittels Electrophoretic Mobility Shift Assay (EMSA) konnten wir weiterhin zeigen, dass es sich um eine Loss of Function Mutation handelt. Im dritten Teil dieser Arbeit habe ich 134 Familien mit Spalthänden und Spaltfüßen mittels Array CGH auf Deletionen und Duplikationen von Chromosom 7q21.3 untersucht. Dort liegt im DYNC1I1 Gen ein bekannter kodierender Extremitäten Enhancer von Dlx5/6. Zusammenfassend habe ich in dieser Arbeit folgende Ergebnisse erzielt: 1) Ich konnte Mutationen und Deletionen von ZAK als molekulare Ursache von Spalthänden identifizieren. 2) Ich konnte zeigen, dass eine homozygote Missens-Mutation im HOXD13 Gen als ursächlich für eine schwere Synpolydaktylie ist. 3) Ich konnte zeigen, dass Deletionen eines kodierenden Extremitäten Enhancers von Dlx5/6 auf Chromosom 7q21.3 in ca. 3% aller Familien mit Spalthänden und Spaltfüßen zu finden sind

Cornelia de lange syndrome

Background: Cornelia de Lange syndrome (CDLS) is a rare multiple congenital anomaly syndrome characterized by a distinctive facial appearance, developmental delay, growth retardation, low birth weight, skeletal formation anomaly, and hirsutism. Case: Here for the first time a case of CDLS from Iran, a 15-week-old male infant who was refereed as a case of multiple congenital anomalies. Clinical investigation showed that the child was a case of CDLS. Conclusion: This is the first case report with CDLS in Iran

ASSOCIATION OF CETP AND ADTRP GENES WITH CORONARY ARTERY DISEASE IN MULTI-ETHNIC SINGAPOREAN POPULATION

Master'sMASTER OF SCIENC

Cornelia de lange syndrome

Background: Cornelia de Lange syndrome (CDLS) is a rare multiple congenital anomaly syndrome characterized by a distinctive facial appearance, developmental delay, growth retardation, low birth weight, skeletal formation anomaly, and hirsutism. Case: Here for the first time a case of CDLS from Iran, a 15-week-old male infant who was refereed as a case of multiple congenital anomalies. Clinical investigation showed that the child was a case of CDLS. Conclusion: This is the first case report with CDLS in Iran

Waardenburg Syndrome Type I in an Iranian Female

Background: Waardenburg syndrome (WS) is a rare, autosomal dominant disorder characterized by congenital hearing loss; dystopia canthorum; broad nasal root; depigmantation of hair, skin or both; and heterochromic iris. WS is classified into four types, WS1, WS2, WS3 and WS4. In this paper, we report a new case of Waardenburg syndrome type I in an Iranian female. Case presentation: This report describes a two-year-old female with Waardenburg syndrome type I with features such as unilateral profound sensorineural hearing loss, white forelock, dystopia canthorum, broad nasal root, hypopigmentation of skin and scalp defect. Conclusion: As no treatment is available for patients with WS1, conservative treatments such as skin graft and referral to a hearing specialist are crucial for the normal development of patients