Ultrastructure abnormalities of collagen and elastin in Arab patients with arterial tortuosity syndrome.

Arterial tortuosity syndrome (ATS) is a rare autosomal recessive disease characterized by elongation and tortuosity of the large- and medium-sized arteries. ATS patients display features that are also found in Ehlers-Danlos syndrome (EDS) patients. ATS is caused by pathogenic mutations in the SLC2A10 gene, which encodes for the glucose transporter, GLUT10. This study aimed at examining the ultrastructure of skin for abnormalities that can explain the loose skin and arterial phenotypes of Arab patients with the p.S81R mutation in SLC2A10. Forty-eight patients with SLC2A10 mutation were recruited for this study. Skin biopsy specimens from three children with ATS and a healthy child were examined by electron microscopy to determine the ultrastructure of collagen and elastin. Histopathologic staining of sections from tissue biopsy specimens was also performed. Large spaces were observed among the collagen fibrils in the skin biopsy specimens obtained from ATS patients, suggesting disorganization of the collagen structures. Furthermore, elastin fiber contents and their thickness are reduced in the skin. In small muscular arteries in the skin from ATS patients, discontinuous internal elastic lamina, lack of myofilaments, and disorganized medial smooth muscle cells with vacuolated cytoplasm are present. The disorganization of collagen fibrils and reduced elastin contents in the skin may explain the loose skin phenotype of ATS patients similar to the EDS patients. The lack of elastin in small muscular arteries may have contributed to the development of arterial tortuosity in these patients.

Novel and recurrent germline mutations in the VHL gene in 5 Arab patients with Von Hippel-Lindau disease.

Inherited germline mutations in the VHL gene cause predisposition to Von Hippel-Lindau (VHL) disease. Patients exhibit benign and cancerous lesions in multiple tissues, including hemangioblastomas, clear cell renal cell carcinoma, cysts in kidneys and pancreas, and pheochromocytomas. Although pathogenic germline mutations in the VHL gene have been widely described in different populations, only a single mutation was previously reported in a family from mixed Arab-Persian ethnicity. Here, we present five Arab patients with two new and two recurrent germline mutations in the VHL gene. These mutations include three in-frame deletions and a missense mutation. Infrequent in-frame deletions in previously described patients from other populations, as well as the presence of new mutations, suggests a distinct spectrum of VHL gene mutations in Arab patients. While pulmonary manifestation has been described rarely in VHL disease, we have identified two patients with a recurrent p.Phe76del in-frame deletion exhibiting multiple nodules in lungs. We also describe a first-ever in-frame deletion in the VHL gene in a patient with VHL type 2C disease, exhibiting bilateral pheochromocytoma. Overall, the study provides an insight into the genotype-phenotype relationship of VHL disease in Arab patients and provides a comparison with previously described patients from other ethnicities.

Rett Syndrome, a Neurodevelopmental Disorder, Whole-Transcriptome, and Mitochondrial Genome Multiomics Analyses Identify Novel Variations and Disease Pathways.

Rett syndrome (RTT) is a severe neurodevelopmental disorder reported worldwide in diverse populations. RTT is diagnosed primarily in females, with clinical findings manifesting early in life. Despite the variable rates across populations, RTT has an estimated prevalence of ∼1 in 10,000 live female births. Among 215 Saudi Arabian patients with neurodevelopmental and autism spectrum disorders, we identified 33 patients with RTT who were subsequently examined by genome-wide transcriptome and mitochondrial genome variations. To the best of our knowledge, this is the first in-depth molecular and multiomics analyses of a large cohort of Saudi RTT cases with a view to informing the underlying mechanisms of this disease that impact many patients and families worldwide. The patients were unrelated, except for 2 affected sisters, and comprised of 25 classic and eight atypical RTT cases. The cases were screened for methyl-CpG binding protein 2 (MECP2), CDKL5, FOXG1, NTNG1, and mitochondrial DNA (mtDNA) variants, as well as copy number variations (CNVs) using a genome-wide experimental strategy. We found that 15 patients (13 classic and two atypical RTT) have MECP2 mutations, 2 of which were novel variants. Two patients had novel FOXG1 and CDKL5 variants (both atypical RTT). Whole mtDNA sequencing of the patients who were MECP2 negative revealed two novel mtDNA variants in two classic RTT patients. Importantly, the whole-transcriptome analysis of our RTT patients' blood and further comparison with previous expression profiling of brain tissue from patients with RTT revealed 77 significantly dysregulated genes. The gene ontology and interaction network analysis indicated potentially critical roles of MAPK9, NDUFA5, ATR, SMARCA5, RPL23, SRSF3, and mitochondrial dysfunction, oxidative stress response and MAPK signaling pathways in the pathogenesis of RTT genes. This study expands our knowledge on RTT disease networks and pathways as well as presents novel mutations and mtDNA alterations in RTT in a population sample that was not previously studied.

Spectrum of the KIT Gene Mutations in Gastrointestinal Stromal Tumors in Arab Patients

Background: Gastrointestinal stromal tumors are the most common mesenchymal tumors of the gastrointestinal tract, which originate from the interstitial cells of Cajal. These tumors are characterized by expression of CD117 and CD34 antigens and activating mutations in the KIT and PDGFRA genes. While KIT and PDGFRA mutations have been extensively studied in other populations, the spectrum of mutations in Arab patients remains unknown. The study aimed at determining the distribution of KIT and PDGFRA mutations and phenotypic characterization of the gastrointestinal stromal tumors in Arab patients. Methods: Sanger sequencing was used to analyze 52 archived gastrointestinal stromal tumors for mutations in the KIT and the PDGFRA genes. Tumor descriptions were obtained from the clinical reports of patients. Results: In these patients, most tumors occur in the stomach, followed by the rest of the digestive tract. A vast majority of tumors express the CD117 and CD34 antigens. Sequencing of the KIT and PDGFRA genes identified five non-synonymous mutations and 26 deletions (25 novel) in exon 11 of the KIT gene. All non-synonymous mutations and deletions affect the juxta-membrane domain, which is known to inhibit ligand-independent activation of the KIT receptor. No mutations were found in the PDGFRA gene. Conclusions: Molecular profiling of the gastrointestinal stromal tumors in Arab patients identified a unique spectrum of mutations in exon 11 of the KIT gene. These data are important for the diagnosis and management of patients of Arab ethnic origin.

Hereditary 1,25-dihydroxyvitamin D-resistant rickets (HVDRR): clinical heterogeneity and long-term efficacious management of eight patients from four unrelated Arab families with a loss of function VDR mutation.

BACKGROUND: Vitamin D regulates the concentrations of calcium and phosphate in blood and promotes the growth and remodeling of bones. The circulating active form of vitamin D, 1,25-dihydroxyvitamin D, binds to the vitamin D receptor (VDR), which heterodimerizes with the retinoid X receptor to regulate the expression of target genes. Inactivating mutations in the VDR gene cause hereditary vitamin D-resistant rickets (HVDRR), a rare disorder characterized by an early onset of rickets, growth retardation, skeletal deformities, hypocalcemia, hypophosphatemia and secondary hyperparathyroidism, and in some cases alopecia. METHODS: We describe eight new HVDRR patients from four unrelated consanguineous families. The VDR gene was sequenced to identify mutations. The management of patients over a period of up to 11 years following the initial diagnosis is assessed. RESULTS: Although all patients exhibit main features of HVDRR and carry the same c.885C>A (p.Y295*) loss of function mutation in the VDR gene, there was heterogeneity of the manifestations of HVDRR-associated phenotypes and developmental milestones. These eight patients were successfully treated over a period of 11 years. All clinical symptoms were improved except alopecia. CONCLUSIONS: The study concludes that VDR sequencing and laboratory tests are essential to confirm HVDRR and to assess the effectiveness of the treatment.

Mutations in MSX1, PAX9 and MMP20 genes in Saudi Arabian patients with tooth agenesis.

Tooth agenesis in human being is the most common congenital anomaly associated with dental development. Mutations in many genes such as MSH homeobox 1 (MSX1), paired box gene 9 (PAX9), ectodysplasin A (EDA) and EDA receptor (EDAR) have been associated with familial form of this condition. However, in large majority of patients, genetic cause could not be identified. The primary aim of present study was to identify the causative mutation(s) in these genes in Saudi Arabian families diagnosed with non-syndromic form of disease. Direct sequencing of coding regions, including exon-intron boundaries of these genes was carried out. All identified nucleotide variations were also tested to exclude possibility of being rare polymorphisms. The sequence analysis of exons and exon-intronic regions of these genes revealed five new mutations that include four in MSX1, one in PAX9 and one single nucleotide polymorphism (SNP) in majority of the patients in MMP20. One novel mutation in exon 1 of MSX1 gene (5354C > G; A40G) was found in three patients. In addition, another novel mutation was detected in two patients in exon 3 (PAX9) as g.10672A > T which changes asparagine to isoleucine at position 40. These mutations were not found in any of the control subjects. A single SNP in MMP20 genes (g.5066A > C) that changes lysine to threonine at position 18 was found in 10% controls as well. Our results for the first time demonstrates that mutations in MSX1 gene might play an important role in hypodontia cases involving pre-molars and is a risk factor for this ethnic population mainly of Arabs and is first report linking these mutations with tooth agenesis.

Recurrent mutation in CDMP1 in a family with Grebe chondrodysplasia: broadening the phenotypic manifestation of syndrome in Pakistani population.

Grebe syndrome (OMIM-200700) is a very rare type of acromesomelic dysplasia with autosomal recessive inheritance. We studied a Pakistani family with two affected individuals having typical features of Grebe chondrodysplasia. Patients were observed with short and deformed limbs having a proximo-distal gradient of severity. Hind-limbs were more severely affected than fore-limbs. Digits on autopods were very short and nonfunctional. Index subject also had nearsightedness. However, symptoms in the craniofacial and axial skeleton were minimal. Genetic analysis revealed four base pair insertion mutation (c.1114insGAGT) in gene coding cartilage-derived morphogenetic protein-1 (CDMP1). This mutation was predicted to cause premature stop codon. The clinical presentation in this study broadens the range of phenotypes associated with CDMP1 mutation in Pakistani population.

Exome sequencing reveals MCM8 mutation underlies ovarian failure and chromosomal instability.

Premature ovarian failure (POF) is a genetically and phenotypically heterogeneous disorder that includes individuals with manifestations ranging from primary amenorrhea to loss of menstrual function prior to age 40. POF presents as hypergonadotropic hypogonadism and can be part of a syndrome or occur in isolation. Here, we studied 3 sisters with primary amenorrhea, hypothyroidism, and hypergonadotropic hypogonadism. The sisters were born to parents who are first cousins. SNP analysis and whole-exome sequencing revealed the presence of a pathogenic variant of the minichromosome maintenance 8 gene (MCM8, c.446C>G; p.P149R) located within a region of homozygosity that was present in the affected daughters but not in their unaffected sisters. Because MCM8 participates in homologous recombination and dsDNA break repair, we tested fibroblasts from the affected sisters for hypersensitivity to chromosomal breaks. Compared with fibroblasts from unaffected daughters, chromosomal break repair was deficient in fibroblasts from the affected individuals, likely due to inhibited recruitment of MCM8 p.P149R to sites of DNA damage. Our study identifies an autosomal recessive disorder caused by an MCM8 mutation that manifests with endocrine dysfunction and genomic instability.

Clinical, neuroimaging, and genetic features of L-2-hydroxyglutaric aciduria in Arab kindreds.

BACKGROUND AND OBJECTIVES: L-2-hydroxyglutaric aciduria is a neurometabolic disorder with autosomal recessive mode of inheritance in which patients exhibit elevated L-2-hydroxyglutaric acid in body fluids, central nervous system manifestations, and increased risk of brain tumor formation. Mutations in L2HGDH gene have been described in L-2-hydroxyglutaric aciduria patients of different ethnicities. The present study was conducted to perform a detailed clinical, imaging and genetic analysis. DESIGN AND SETTINGS: A cross-sectional clinical genetic study of 16 L-2-hydroxyglutaric aciduria patients from 4 Arab consanguineous families examined at the metabolic clinic of the hospital. PATIENTS AND METHODS: Genomic DNA was isolated from the blood of 12 patients and 10 unaffected family members, and the L2HGDH gene was sequenced. DNA sequences were compared to the L2HGDH reference sequence from GenBank. RESULTS: All patients exhibit characteristic clinical, biochemical, and imaging features of L-2-hydroxyglutaric aciduria, and 4 patients exhibited increased incidence of brain tumors. The sequencing of the L2HGDH gene revealed the c.1015delA, c.1319C > A, and c.169G > A mutations in these patients. These mutations encode for the p.Arg339AspfsX351, p.Ser440Tyr, and p.Gly57Arg changes in the L2HGDH protein, respectively. The c.169G > A mutation, which was shown to have a common origin in Italian and Portuguese patients, was also discovered in Arab patients. Finding of the homozygous c.159T SNP associated with the c.169G > A mutation in Arab patients points to an independent origin of this mutation in Arab population. CONCLUSION: The detailed description of clinical manifestations and L2HGDH mutation in this study is useful for diagnosis of L-2-hydroxyglutaric aciduria in Arab patients. While reoccurrence of an L2HGDH mutation in L-2-hydroxyglutaric aciduria patients of different ethnicity is extremely rare, the c.169G mutation has an independent origin in Arab patients. It is likely that this mutation may also be present in patients of other ethnicities.

Characterization of a distinct lethal arteriopathy syndrome in twenty-two infants associated with an identical, novel mutation in FBLN4 gene, confirms fibulin-4 as a critical determinant of human vascular elastogenesis.

BACKGROUND: Vascular elasticity is crucial for maintaining hemodynamics. Molecular mechanisms involved in human elastogenesis are incompletely understood. We describe a syndrome of lethal arteriopathy associated with a novel, identical mutation in the fibulin 4 gene (FBLN4) in a unique cohort of infants from South India. METHODS: Clinical characteristics, cardiovascular findings, outcomes and molecular genetics of twenty-two infants from a distinct population subgroup, presenting with characteristic arterial dilatation and tortuosity during the period August 2004 to June 2011 were studied. RESULTS: Patients (11 males, 11 females) presented at median age of 1.5 months, belonging to unrelated families from identical ethno-geographical background; eight had a history of consanguinity. Cardiovascular features included aneurysmal dilatation, elongation, tortuosity and narrowing of the aorta, pulmonary artery and their branches. The phenotype included a variable combination of cutis laxa (52%), long philtrum-thin vermillion (90%), micrognathia (43%), hypertelorism (57%), prominent eyes (43%), sagging cheeks (43%), long slender digits (48%), and visible arterial pulsations (38%). Genetic studies revealed an identical c.608A > C (p. Asp203Ala) mutation in exon 7 of the FBLN4 gene in all 22 patients, homozygous in 21, and compound heterozygous in one patient with a p. Arg227Cys mutation in the same conserved cbEGF sequence. Homozygosity was lethal (17/21 died, median age 4 months). Isthmic hypoplasia (n = 9) correlated with early death (≤4 months). CONCLUSIONS: A lethal, genetic disorder characterized by severe deformation of elastic arteries, was linked to novel mutations in the FBLN4 gene. While describing a hitherto unreported syndrome in this population subgroup, this study emphasizes the critical role of fibulin-4 in human elastogenesis.

Prognostically significant fusion oncogenes in Pakistani patients with adult acute lymphoblastic leukemia and their association with disease biology and outcome.

BACKGROUND AND OBJECTIVES: Chromosomal abnormalities play an important role in genesis of acute lymphoblastic leukemia (ALL) and have prognostic implications. Five major risk stratifying fusion genes in ALL are BCR-ABL, MLL-AF4, ETV6-RUNX11, E2A-PBX1 and SIL-TAL1. This work aimed to detect common chromosomal translocations and associated fusion oncogenes in adult ALL patients and study their relationship with clinical features and treatment outcome. METHODS: We studied fusion oncogenes in 104 adult ALL patients using RT-PCR and interphase-FISH at diagnosis and their association with clinical characteristics and treatment outcome. RESULTS: Five most common fusion genes i.e. BCR-ABL (t 9; 22), TCF3-PBX1 (t 1; 19), ETV6-RUNX1 (t 12; 21), MLL-AF4 (t 4; 11) and SIL-TAL1 (Del 1p32) were found in 82/104 (79%) patients. TCF3-PBX1 fusion gene was associated with lymphadenopathy, SIL-TAL positive patients had frequent organomegaly and usually presented with a platelets count of less than 50 x10(9)/l. Survival of patients with fusion gene ETV6-RUNX1 was better when compared to patients harboring other genes. MLL-AF4 and BCR-ABL positivity characterized a subset of adult ALL patients with aggressive clinical behaviour and a poor outcome. CONCLUSIONS: This is the first study from Pakistan which investigated the frequency of 5 fusion oncogenes in adult ALL patients, and their association with clinical features, treatment response and outcome. Frequencies of some of the oncogenes were different from those reported elsewhere and they appear to be associated with distinct clinical characteristics and treatment outcome. This information will help in the prognostic stratification and risk adapted management of adult ALL patients.

Autoimmune polyglandular syndrome type 1 in Saudi children.

OBJECTIVE: To describe the clinical, biochemical, and immunological manifestations of autoimmune polyglandular syndrome type 1 (APS-1) in a Saudi population. METHODS: The medical files of 7 consanguineous Saudi families with 20 affected siblings were retrospectively reviewed. They were followed at the Pediatric Endocrinology Clinic, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia for a mean duration of 6 years (January 2000 to December 2009). The age of the affected children ranged from 2-17 years. The included patients had at least 2 out of the 3 major clinical diagnostic criteria of APS-1. RESULTS: Fourteen children had neonatal chronic mucocutaneous candidiasis affecting the nails and mouth. The most commonly presenting endocrine disease among APS-1 patients was hypoparathyroidism. Eight patients had autoimmune Addison's disease. Hypothyroidism was diagnosed in 3 patients, and 9 patients had alopecia universalis. Other endocrine and autoimmune disorders were infrequently seen including type 1 diabetes, growth hormone deficiency, celiac disease, autoimmune hepatitis, and keratoconjuctivitis. CONCLUSION: Autoimmune polyglandular syndrome type 1, although an uncommon disorder in Saudi children affects multiple endocrine glands, and is associated with several autoimmune diseases where alopecia universalis is a common finding.

A novel HAX1 gene mutation in severe congenital neutropenia (SCN) associated with neurological manifestations.

Autosomal recessive severe congenital neutropenia (SCN) results from a maturation arrest of granulopoiesis at the level of promyelocytes and apoptosis of myeloid cells. In SCN patients, mutations have been described in the HAX1 gene. Most of the SCN patients who carry nonsense mutations that are common to both transcript variants of the HAX1 gene also exhibit neurological deficits. This study describes an SCN patient with neurological manifestations including daily episodes of atonic seizures, learning disabilities, and developmental delay. Sequencing of the HAX1 gene of this SCN patient identified a novel nonsense c.463_464insC homozygous mutation in exon 3, which is common to both transcript variants of the gene. This mutation encodes for a p.Gln155ProfsX14 change and causes premature truncation of the HAX1 protein. Neutrophils isolated from the patient exhibited spontaneous apoptosis and loss of inner mitochondrial membrane potential, which were further enhanced upon treatment with hydrogen peroxide. This study adds to the spectrum of novel HAX1 gene mutations and disease manifestations in ethnically distinct SCN patients. Our report describes the only nonsense mutation in the HAX1 gene present in SCN patients of Arab origin.

Multiple paraganglioma syndrome type 4 due to succinate dehydrogenase B mutation: diagnostic and therapeutic challenges of a skull base paraganglioma masquerading as nasopharyngeal cancer.

OBJECTIVE: To report a case of hereditary paraganglioma and describe the underlying genetic mutation and response to iodine 131 metaiodobenzylguanidine (MIBG) therapy. METHODS: We describe the clinical course and laboratory and imaging findings of the study patient. RESULTS: A 38-year-old man presented in May 2005 with pseudobulbar palsy and was initially thought to have nasopharyngeal cancer because computed tomography of the head showed a large, locally invasive nasopharyngeal tumor. During tumor staging, abdominal computed tomography showed a large, locally invasive left adrenal tumor. Urinary normetanephrine was extremely elevated at 39,831 microg/24 h (reference range, 0-580 microg/24 h), while metanephrine was normal. MIBG scan showed uptake in the left adrenal gland and in the skull mass. Biopsy of the nasopharyngeal mass confirmed the diagnosis of paraganglioma. The patient underwent resection of the 13-cm pheochromocytoma in the left adrenal gland, with resection of part of the colon and kidney. Postoperatively, urinary normetanephrine dropped to 9339 microg/24 h. The nasopharyngeal paraganglioma was inoperable. The patient was treated with 3 doses of MIBG-201, 190, and 225 mCi in August 2007, January 2008, and January 2009, respectively. Urinary normetanephrine normalized, and follow-up magnetic resonance imaging showed a 60% reduction in the size of the nasopharyngeal tumor. Genetic testing revealed a C to T transition at nucleotide 268 in exon 3 of the SDHB gene, resulting in a change from an arginine to a stop codon (Arg90X) and leading to a truncated SDHB protein. CONCLUSIONS: This case illustrates the diagnostic and therapeutic challenges of hereditary paraganglioma and the value of genetic testing. It also demonstrates the effectiveness of MIBG therapy for inoperable paragangliomas.

Novel and recurrent mutations in the C1NH gene of Arab patients affected with hereditary angioedema.

BACKGROUND: Autosomal dominant hereditary angioedema (HAE) results in episodes of subcutaneous edema in any body part and/or submucosal edema of the upper respiratory or gastrointestinal tracts. This disorder is caused by mutations in the C1NH gene, many of which have been described primarily in European patients. However, the genetic cause of HAE in Middle Eastern Arab patients has not yet been determined. METHODS: Four unrelated Arab families, in which 15 patients were diagnosed with HAE, were studied. DNA from 13 patients was analyzed for mutations in the C1NH gene by DNA sequencing. RESULTS: Three novel and 2 recurrent mutations were identified in the C1NH gene of HAE patients. In family 1, the patient was heterozygous for a novel c.856C>T and a recurrent c.1361T>A missense mutation encoding for p.Arg264Cys and p.Val432Glu, respectively. In patients from family 2, a novel c.509C>T missense mutation encoding for a p.Ser148Phe was identified. In patients from family 3, a novel c.1142delC nonsense mutation encoding for a p.Ala359AlafsX15 was discovered. In family 4, a recurrent c.1397G>A missense mutation encoding for a p.Arg444His was present. CONCLUSION: This is the first ever report of C1NH gene mutations in Middle Eastern Arab patients. Our study suggests that, despite the numerous existing mutations in the C1NH gene, there are novel and recurrent mutations in HAE patients of non-European origin. We conclude that the spectrum of C1NH gene mutations in HAE patients is wider due to the likely presence of novel and recurrent mutations in patients of other ethnicities.

Novel FBP1 gene mutations in Arab patients with fructose-1,6-bisphosphatase deficiency.

UNLABELLED: Deficiency of fructose-1,6-bisphosphatase (FBP) results in impaired gluconeogenesis, which is characterized by episodes of hyperventilation, apnea, hypoglycemia, and metabolic and lactic acidosis. This autosomal recessive disorder is caused by mutations in the FBP1 gene, which encodes for fructose-1,6-bisphosphatase 1 (FBP1). Although FBP1 gene mutations have been described in FBP-deficient individuals of various ethnicities, there has been limited investigation into the genetics of this disorder in Arab patients. This study employed five consanguineous Arab families, in which 17 patients were clinically diagnosed with FBP deficiency. Seven patients and six carrier parents were analyzed for mutations in the FBP1 gene. DNA sequencing of the FBP1 gene identified two novel mutations in these families. A novel six nucleotide repetitive insertion, c114_119dupCTGCAC, was identified in patients from three families. This mutation encodes for a duplication of two amino acids (p.Cys39_Thr40dup) in the N-terminal domain of FBP1. A novel nonsense c.841G>T mutation encoding for a p.Glu281X truncation in the active site of FBP1 was discovered in patients from two families. The newly identified mutations in the FBP1 gene are predicted to produce FBP1 deficiency. These mutations are the only known genetic causes of FBP deficiency in Arab patients. The p.Cys39_Thr40dup is the first reported amino acid duplication in FBP deficiency patients. CONCLUSION: This study provides a strong rationale for genetic testing of FBP deficient patients of Arab ethnicity for recurrent or novel mutations in the FBP1 gene.

A novel missense and a recurrent mutation in SLC2A10 gene of patients affected with arterial tortuosity syndrome.

Arterial tortuosity syndrome is an autosomal recessive disorder characterized by severe tortuosity of greater and systemic arteries in affected individuals. In addition, patients display connective tissue features which include hyperextensible skin, hypermobility of joints and characteristic facial features. This syndrome is caused by mutation in SLC2A10 gene which encodes for the facilitative glucose transporter, GLUT10. We describe seven patients of two unrelated Saudi Arabian families who display tortuosity, dilatation and stenosis of arteries, pulmonary hypertension and other cardiovascular manifestations. These patients exhibit characteristic connective tissue phenotypes and distinctive facial features. In the single patient of Family 1, sequencing of the candidate gene, SLC2A10, identified a novel missense c.313C>T mutation encoding a p.Arg105Cys substitution in the second extracellular domain of GLUT10. The Arg105 in GLUT10 is highly conserved across species and its replacement with cysteine is predicted to be pathogenic. In the second family, all of the six affected individuals carry recurrent c.243C>G missense mutation encoding a p.Ser81Arg change in the third transmembrane domain of GLUT10. The present study suggests that there exists an intra- and inter-familial phenotypic variability in arterial tortuosity patients carrying identical or different mutations in SLC2A10 gene. While skin hyperextensibility, small joint hypermobility, and facial features are similarly expressed in these patients, there is a range of other phenotypes which include arterial tortuosity and associated complications, and abnormalities of other organs.

A novel non-sense mutation in the SLC2A10 gene of an arterial tortuosity syndrome patient of Kurdish origin.

Arterial tortuosity syndrome (ATS) is a rare autosomal recessive disorder in which patients display tortuosity of arteries in addition to hyperextensible skin, joint laxity, and other connective tissue features. This syndrome is caused by mutations in the SLC2A10 gene. In this article we describe an ATS girl of Kurdish origin who, in addition to arterial tortuosity and connective tissue features, displays stomach displacement within the thorax and bilateral hip dislocation. Clinical details of this patient have been reported previously. Sequencing of the SLC2A10 gene identified a novel homozygous non-sense c.756C>A mutation in this patient's DNA. This mutation in the SLC2A10 gene replaces a cysteine encoding codon with a stop signal. This is believed to cause a premature truncation of GLUT10 protein in this patient. We conclude that patients of Kurdish origin who display arterial tortuosity associated with skin hyperextensibility, joint hypermobility, and characteristic facial features may carry mutations in the SLC2A10 gene.

Grebe-type chondrodysplasia: a novel missense mutation in a conserved cysteine of the growth differentiation factor 5.

Grebe-type chondrodysplasia is a congenital skeletal disorder that is characterized by markedly shortened limbs and very short digits. This defect has an autosomal recessive mode of inheritance and results from mutations in the growth differentiation factor 5 (GDF5) gene. Here, we report three affected children in a consanguineous family who display typical features of Grebe-type chondrodysplasia. Sequencing of the GDF5 genes of the affected children identified a novel c.1285T>C mutation encoding a p.Cys429Arg substitution. The Cys429 of human GDF5 belongs to a group of seven cysteines, which are highly conserved across species and among the various members of the transforming factor-beta (TGF-beta) super family of proteins. These cysteines are essential for the structure, processing, and activity of these proteins. Therefore, it is possible that the p.Cys429Arg change in the GDF5 has produced an inactive protein, resulting in a Grebe-type chondrodysplasia phenotype in the affected children. The absence of skeletal abnormalities in the carrier parents suggests that the p.Cys429Arg change did not produce a dominant negative effect or haploinsufficiency in these individuals. This finding differs from the previous report of skeletal abnormalities in heterozygous individuals of Grebe-type chondrodysplasia families.

Profound biotinidase deficiency in a child with predominantly spinal cord disease.

Biotinidase deficiency is an autosomal recessively inherited disorder that manifests during childhood with various cutaneous and neurological symptoms particularly seizures, hypotonia, and developmental delay. Spinal cord disease has been reported rarely. We describe a 3-year-old boy with profound biotinidase deficiency who presented with progressive spastic paraparesis and ascending weakness in the absence of the usual characteristic neurological manifestations. Supplementation with biotin resulted in resolution of paraparesis with persistent mild spasticity in the lower limbs. DNA mutation analysis revealed that he was homozygous for a novel missense mutation (C>T1339;H447Y) in the BTD gene. This case indicates that biotinidase deficiency should be included in the differential diagnosis of subacute myelopathy and emphasizes the importance of a prompt diagnosis to prevent irreversible neurological damage.