Aggrecan-related bone disorders; a novel heterozygous ACAN variant associated with spondyloepimetaphyseal dysplasia expanding the phenotypic spectrum and review of literature.

BACKGROUND: Spondyloepimetaphyseal dysplasias (SEMD) are a large group of skeletal disorders represented by abnormalities of vertebrae in addition to epiphyseal and metaphyseal areas of bones. Several genes have been identified underlying different forms. ACAN gene mutations were found to cause Aggrecan-related bone disorders (spondyloepimetaphyseal dysplasias,spondyloepiphyseal dysplasias, familial osteochondritis dissecans and short stature syndromes). This study aims to find the disease causing variant in Egyptian patient with SEMD using whole exome sequencing. METHODS: Whole-exome sequencing was performed for an Egyptian male patient who presented with short stature, clinical and radiological features suggestive of unclassified SEMD. RESULTS: The study identified a novel de novo heterozygous ACAN gene variant (c.7378G>A; p.Gly2460Arg) in G3 domain. Mutations in ACAN gene have been more commonly associated with short stature than SEMD. The phenotype of our patient was intermediate in severity between spondyloepiphyseal dysplasia presentation; Kimberley type(SEDK) and Spondyloepimetaphyseal dysplasias Aggrecan (SEMDAG) CONCLUSIONS: Whole exome sequencing revealed a novel de novo ACAN gene variant in patient with SEDK. The clinical and skeletal phenotype of our patient was much severe than those reported originally and showed more metaphyseal involvement. To the best of our knowledge, two previous studies reported a heterozygous variant in ACAN with spondyloepiphyseal dysplasia presentation; Kimberley type.

Genetic study of eight Egyptian patients with pycnodysostosis: identification of novel CTSK mutations and founder effect.

This is the first Egyptian study with detailed clinical and orodental evaluation of eight patients with pycnodysostosis and identification of four mutations in CTSK gene with two novel ones and a founder effect. INTRODUCTION: Pycnodysostosis is a rare autosomal recessive skeletal dysplasia due to mutations in the CTSK gene encoding for cathepsin K, a lysosomal cysteine protease. METHODS: We report on the clinical, orodental, radiological, and molecular findings of eight patients, from seven unrelated Egyptian families with pycnodysostosis. RESULTS: All patients were offspring of consanguineous parents and presented with the typical clinical picture of the disorder including short stature, delayed closure of fontanels, hypoplastic premaxilla, obtuse mandibular angle, and drum stick terminal phalanges with dysplastic nails. Their radiological findings showed increased bone density, acro-osteolysis, and open cranial sutures. Mutational analysis of CTSK gene revealed four distinct homozygous missense mutations including two novel ones, c.164A>C (p. K55T) and c.433G>A (p.V145M). The c.164A>C (p. K55T) mutation was recurrent in three unrelated patients who also shared similar haplotype, suggesting a founder effect. CONCLUSION: Our findings expand the mutational spectrum of CTSK gene and emphasize the importance of full clinical examination of all body systems including thorough orodental evaluation in patients with pycnodysostosis.

ROBERTS SYNDROME: CLINICAL AND CYTOGENETIC STUDIES IN 8 EGYPTIAN PATIENTS AND MOLECULAR STUDIES IN 4 PATIENTS WITH GENOTYPE/PHENOTYPE CORRELATION.

The Roberts syndrome (RBS) is a rare autosomal recessive disorder caused by mutation in ESCO2 gene. Among over 150 reported international cases, 16 cases are Egyptian including the presently reported patients. The current study reports 8 new Egyptian patients from 7 unrelated consanguineous families investigating clinical phenotype as well as cytogenetic changes in all cases and mutational spectrum in 4 cases. Clinical, orodental, cytogenetic and molecular studies were done to investigate genotype/phenotype correlation. Evaluation of the studied 8 patients showed that they all exhibited the main limb and craniofacial features of Roberts syndrome. Cytogenetic studies including centromeric separation and puffing by Giemsa and DAPI stains and for the first time in Egypt analysis for premature centromeric division by FISH showed consistent centromeric separation in all studied cases. Molecular studies of 4 available patients showed that they all have ESCO2 gene mutation. We conclude that RBS has a well-defined clinical spectrum. The cytogenetic changes are due to sister chromatid cohesion defects which lead to mitotic dysfunction. We confirmed previous results of lack of genotype/phenotype correlation. We also confirmed that the severity of limb malformation correlates with craniofacial manifestations. We recommend detailed evaluation of orodental changes for further definition of the phenotype and for proper patient management. We emphasize the need for further studies for the frequency of premature centromeric separation by FISH as a possible indicator of phenotypic severity.

Zoledronic acid in children with osteogenesis imperfecta and Bruck syndrome: a 2-year prospective observational study.

UNLABELLED: Treatment with zoledronic acid (ZA) over 2 years, among 33 children with osteogenesis imperfecta (OI) and five Bruck syndrome cases, showed reduction in fracture rates, pain, and improvement in bone mineral density (BMD) and motor milestones of development. This is the first study reporting the use of bisphosphonates in patients with Bruck syndrome (BS). INTRODUCTION: OI and BS are genetic disorders that result in bone fragility and reduced BMD. There is little literature describing the efficacy and safety of ZA in this population. In this study, we assess the response to treatment with ZA at six monthly intervals in Egyptian children with OI and BS for a period of 2 years. METHODS: Thirty-three patients with OI and five patients with BS were treated with 0.1 mg/kg ZA intravenously every 6 months for 2 years during which they were followed up using different parameters. A clinical severity score (CSS) was applied to the patients before and 2 years after the start of therapy. Comparison of disease severity and response to ZA treatment between autosomal-dominant (AD) and autosomal-recessive (AR) OI patients was also done. RESULTS: After 6 months of treatment, OI and BS patients showed a significant increase in BMD Z-scores (P < 0.003 in the spine and P < 0.004 in the hip), together with a significant drop in fracture rate (P < 0.001), relief of pain (P < 0.001), and improvement in ambulation (P < 0.001). CSS was significantly reduced after 2 years of treatment in both OI and BS patients. AR-OI patients were more severely affected than AD-OI patients and showed more significant improvement. CONCLUSION: Zoledronic acid proved to be safe and effective in the treatment of OI and BS. The biannual infusion protocol was convenient to patients. There was a positive correlation between disease severity and benefits of the treatment. The use of the CSS proved to be of value in the assessment of the degree of severity in OI, and with some modifications, it was a valuable tool for the assessment of response to treatment.

Mutations in CUL7, OBSL1 and CCDC8 in 3-M syndrome lead to disordered growth factor signalling.

3-M syndrome is a primordial growth disorder caused by mutations in CUL7, OBSL1 or CCDC8. 3-M patients typically have a modest response to GH treatment, but the mechanism is unknown. Our aim was to screen 13 clinically identified 3-M families for mutations, define the status of the GH-IGF axis in 3-M children and using fibroblast cell lines assess signalling responses to GH or IGF1. Eleven CUL7, three OBSL1 and one CCDC8 mutations in nine, three and one families respectively were identified, those with CUL7 mutations being significantly shorter than those with OBSL1 or CCDC8 mutations. The majority of 3-M patients tested had normal peak serum GH and normal/low IGF1. While the generation of IGF binding proteins by 3-M cells was dysregulated, activation of STAT5b and MAPK in response to GH was normal in CUL7(-/-) cells but reduced in OBSL1(-/-) and CCDC8(-/-) cells compared with controls. Activation of AKT to IGF1 was reduced in CUL7(-/-) and OBSL1(-/-) cells at 5 min post-stimulation but normal in CCDC8(-/-) cells. The prevalence of 3-M mutations was 69% CUL7, 23% OBSL1 and 8% CCDC8. The GH-IGF axis evaluation could reflect a degree of GH resistance and/or IGF1 resistance. This is consistent with the signalling data in which the CUL7(-/-) cells showed impaired IGF1 signalling, CCDC8(-/-) cells showed impaired GH signalling and the OBSL1(-/-) cells showed impairment in both pathways. Dysregulation of the GH-IGF-IGF binding protein axis is a feature of 3-M syndrome.

A report of three patients with MMP2 associated hereditary osteolysis.

Osteolysis syndromes are rare hereditary disorders characterized by destruction and resorption of affected bones. The current study adds three new patients from two unrelated consanguineous families with a severe form of inherited osteolysis. Clinical examination, radiological, biochemical, ultrastructural and molecular studies were conducted. Clinical and radiological studies suggested the diagnosis of Torg-Winchester syndrome. The three affected patients were homozygous for novel MMP2 gene mutations which confirmed the diagnosis. Our patients are the first to be reported from Egypt thus, supporting the pan ethnic nature of the disease.

The most encountered groups of genetic disorders in Giza Governorate, Egypt.

This study presents the prevalence, relative frequency, and analysis of genetic diseases/malformations in 73260 individuals. Cases included were ascertained from: Pediatric outpatient clinics of two governmental hospitals and two primary health care centers (PHCCs) in Giza Governorate; Neonatal intensive care unit (NICU) in the selected hospitals and Outpatients Human Genetics Clinics (NRC). 62819 persons visited the outpatients clinics of selected hospitals and PHCCs in Giza governorate. Out of these persons 731 cases (1.16%) proved to have known genetic disorders or malformations. 7755 neonates were delivered in the selected hospitals. Out of these neonates 666 newborns entered NICU and 3% (20 neonates) of them had genetic or congenital disorders. Also, 2686 patients were ascertained from the Human Genetics Clinics, NRC. The overall parental consanguinity rate among the 3417 diagnosed cases was 55%, ranging from 29.5-75%. The study showed a high prevalence of genetic/malformation disorders among Egyptians, with frequencies comparable to other Arab populations (Tab. 4, Ref. 25). Full Text (Free, PDF) www.bmj.sk.

Partial trisomy of the distal part of 10q: a report of two Egyptian cases.

Partial trisomy of the distal third of the long arm of chromosome 10 is a well defined but rare syndrome. Most cases result from an unbalanced translocation. Growth retardation, developmental delay and characteristic dysmorphic features are well described in the syndrome. This report includes 2 Egyptian cases with partial 10q trisomy involving different breakpoints. Cases were subjected to full clinical examination and detailed cytogenetic analysis using conventional and FISH studies. Results showed that the karyotype of case 1 was 46,XX,der(7)t(7;10)(p22;q23).ish(wcp7+;wcpl0+) and the karyotype of case 2 was 46,XX,der(7)t(7;10)(p22;q25).ish(wcp7+;wcp 10+). The chromosomal abnormalities in case 1 resulted from a paternal balanced translocation while case 2 resulted from a maternal balanced translocation involving chromosomes 10 and 7 in both cases. The probands' phenotypes were correlated to the breakpoints and compared to previously reported cases with partial trisomy 10q. Both cases had the well characterized phenotype of the distal trisomy of 10q in the form of mental retardation, microcephaly, characteristic dysmorphic facies and limb anomalies as trisomy in both cases involved the 10q25-->qter region. However, case 1 with 10q23-->qter duplication showed more severe clinical manifestations than case 2 with less extensive 10q25-->qter trisomy. These included severe failure to thrive, cardiac involvement and death from respiratory and heart failure. This study confirmed that unbalanced chromosome regions of the long arm of chromosome 10 play an important role in developmental malformations and that a more severe form is associated with involvement of 10q23. It also emphasizes the importance of increasing public awareness regarding these chromosomal rearrangements and the importance of genetic counseling and prenatal diagnosis to avoid recurrences and associated family stress. This was clearly demonstrated in the second family in this study as the couple refused any follow up or further investigations due to religious beliefs despite their social and educational level.

Phenotypic and cytogenetic spectrum of 9p trisomy.

Trisomy 9p is one of the most frequent autosomal anomalies compatible with long survival rate. The spectrum of clinical severity in trisomy 9 roughly correlates with the extent of trisomic chromosome material. Trisomy 9p is a clinically well delineated syndrome and of all stigmata craniofacial dysmorphism is most specific. In this study we report five cases with de novo trisomy 9p. The study aimed at the identification of the genotype/phenotype correlations in patients with different breakpoints. GTG banding, DAPI stain, whole chromosome paint, centromere, telomere and 9p21 specific locus probes demonstrated that partial trisomy 9p in case 1 was due to isochromosome 9p with translocation of the long arm of re-arranged chromosome 9 onto the short arm of chromosome 13, cases 2 and 3 had intrachromosomal duplication of the short arm of chromosome 9 [dup(9)(p21p24)], case 4 had "classical" 9p trisomy and case 5 had duplication of whole short arm and part of the long arm of chromosome 9 (partial 9 trisomy). Although cases 1 to 4 had trisomy involving 9p, cases 1 and 2 exhibited the classical clinical manifestations of 9p trisomy, while cases 3 and 4 had additional features overlapping with Coffin-Siris syndrome. The present study strengthens the association of Coffin-Siris syndrome and 9p, the significance of such observations may point to possible gene location of Coffin-Siris syndrome on 9p. Case 5 had additional manifestations more than those typical of trisomy 9p which could be due to duplication of 9q21 region. Wide gap between 1st and 2nd toes, observed in the studied cases, can be added to the phenotype of this trisomy. Three of our cases had brain malformations, case 3 had dilated ventricles with hypogenesis of corpus callosum, case 4 had agenesis of corpus callosum, and case 5 had Dandy-Walker malformation. We also suggest that dosage effects of genes located in 9pter-q22 contribute to the etiology of Dandy-Walker syndrome. We recommend MRI studies as a routine in all cases with trisomy 9p.

Familial congenital brachial palsy: a report of two affected Egyptian families.

Congenital brachial palsy is still a relatively common birth defect and almost a sporadic disorder. This work presents 2 unrelated Egyptian families; had several members in successive generations with severe unilateral congenital brachial palsy. Pedigree analysis of both families and the high rate of consanguinity among them are highly suggestive of autosomal recessive inheritance with variable expression.

Expanding the phenotypic spectrum of the Baller-Gerold syndrome.

We report on two sisters off-spring of healthy consanguineous parents, where their major clinical features absent thumb, radial aplasia and craniosynostosis led to a diagnosis of Baller-Gerold syndrome BGS (OMIM:218600). Syndromes with associated preaxial reduction defects mainly Fanconi pancytopenia, VATER association, Rothmund-Thompson and Roberts phocomelia syndrome were excluded by proper clinical and cytogenetic studies. In addition to craniosynostosis and radial deficiency, our studied cases had absent or hypoplastic thumbs, postaxial polydactyly in the left foot, genital anomalies and orodental manifestations. Review of the literature depicted phenotypic variability of BGS. The presence of affected sibs the offspring of consanguineous parents confirms autosomal recessive inheritance. The observation of associated postaxial polydactyly, blue sclera, rotatory nystagmus, other skeletal and orodental anomalies broadened the spectrum of phenotypic variability. Awareness of the expanded phenotypic spectrum will improve the diagnosis and genetic counseling of BGS.

Molecular mechanisms of neuromuscular blocking agents: is the increased understanding of importance to the practising anaesthetist?

A neuromuscular blocking agent is an essential component of many general anaesthetics. Although a great deal is known about the neuromuscular junction, the site of action of these agents, their precise mode of action remains unclear. This article reviews our present knowledge of the anatomy and physiology of neuromuscular transmission and the ways in which clinically useful drugs may modify this system. The decisions involved in clinical choice of which agent to use are described with particular respect to basic physiology and pharmacology and also to potential interactions with other drugs.

Modification to the Sprotte spinal needle.

The large lateral hole of the Sprotte needle is claimed to aid cerebrospinal fluid efflux during the performance of spinal anaesthesia. Using theoretical calculations and practical measurement we have shown that reducing the area of the lateral hole to that of the cross sectional area of the needle does not affect the flow rate. We suggest this modified Sprotte needle is an improved design which has the potential advantages of reducing the incidence of inadequate spinal anaesthesia and strengthening the needle tip.