GZF1 Mutations Expand the Genetic Heterogeneity of Larsen Syndrome.

Larsen syndrome is characterized by the dislocation of large joints and other less consistent clinical findings. Heterozygous FLNB mutations account for the majority of Larsen syndrome cases, but biallelic mutations in CHST3 and B4GALT7 have been more recently described, thus confirming the existence of recessive forms of the disease. In a multiplex consanguineous Saudi family affected by severe and recurrent large joint dislocation and severe myopia, we identified a homozygous truncating variant in GZF1 through a combined autozygome and exome approach. Independently, the same approach identified a second homozygous truncating GZF1 variant in another multiplex consanguineous family affected by severe myopia, retinal detachment, and milder skeletal involvement. GZF1 encodes GDNF-inducible zinc finger protein 1, a transcription factor of unknown developmental function, which we found to be expressed in the eyes and limbs of developing mice. Global transcriptional profiling of cells from affected individuals revealed a shared pattern of gene dysregulation and significant enrichment of genes encoding matrix proteins, including P3H2, which hints at a potential disease mechanism. Our results suggest that GZF1 mutations cause a phenotype of severe myopia and significant articular involvement not previously described in Larsen syndrome.

Inclusion of joint laxity, recurrent patellar dislocation, and short distal ulnae as a feature of Van Den Ende-Gupta syndrome: a case report.

BACKGROUND: Van Den Ende-Gupta Syndrome (VDEGS) is an extremely rare autosomal recessive syndrome with less than 20 reported families (approximately 40 patients) in the worldwide literature. CASE PRESENTATION: We have assessed one consanguineous Saudi family with typical features of VDEGS. Two siblings were affected with almost identical features; including blepharophimosis, arachnodactyly, flexion contractures of the elbows, camptodactyly, slender ribs, hooked lateral clavicular ends, and bilateral radial head dislocations. Both patients had several unusual features; including joint laxity, flat feet, recurrent patellar dislocations, and bilateral short distal ulnae. Full sequencing of SCARF2 revealed a homozygous mutation c.773G > A (p. Cys258Tyr) in both affected children. The parents (both with no abnormalities) were heterozygous for the same mutation. CONCLUSION: Joint laxity, recurrent patellar dislocations, and short distal ulnae should be included as part of the clinical spectrum of VDEGS.

Exome sequencing identifies novel NTRK1 mutations in patients with HSAN-IV phenotype.

Hereditary sensory autonomic neuropathy type IV (HSAN-IV) is a rare autosomal recessive disorder that usually begins in infancy and is characterized by anhidrosis, insensitivity to noxious stimuli leading to self-mutilating behavior, and intellectual disability. HSAN-IV is caused by mutations in the neurotrophic tyrosine kinase receptor type 1 gene, NTRK1, encoding the high-affinity receptor of nerve growth factor (NGF) which maps to chromosome 1q21-q22. Patients with HSAN-IV lack all NGF-dependent neurons, the primary afferents and sympathetic postganglionic neurons leading to lack of pain sensation and the presence of anhidrosis, respectively. Herein, we report nine patients from nine unrelated families with HSAN-IV due to various mutations in NTRK1, five of which are novel. These are three missense and two nonsense mutations distributed in various domains of NTRK1 involved in binding of NGF. The affected patients had variable intellectual deficits, and some had delayed diagnosis of HSAN-IV. In addition to being the first report of HSAN-IV from the Arabian Peninsula, this report expands the mutational spectrum of patients with NTRK1 mutations and provides further insights for molecular and clinical diagnosis.

A novel X-linked disorder with developmental delay and autistic features.

OBJECTIVE: Genomic duplications that lead to autism and other human diseases are interesting pathological lesions since the underlying mechanism almost certainly involves dosage sensitive genes. We aim to understand a novel genomic disorder with profound phenotypic consequences, most notably global developmental delay, autism, psychosis, and anorexia nervosa. METHODS: We evaluated the affected individuals, all maternally related, using childhood autism rating scale (CARS) and Vineland Adaptive scales, magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) brain, electroencephalography (EEG), electromyography (EMG), muscle biopsy, high-resolution molecular karyotype arrays, Giemsa banding (G-banding) and fluorescent in situ hybridization (FISH) experiments, mitochondrial DNA (mtDNA) sequencing, X-chromosome inactivation study, global gene expression analysis on Epstein-Barr virus (EBV)-transformed lymphoblasts, and quantitative reverse-transcription polymerase chain reaction (qRT-PCR). RESULTS: We have identified a novel Xq12-q13.3 duplication in an extended family. Clinically normal mothers were completely skewed in favor of the normal chromosome X. Global transcriptional profiling of affected individuals and controls revealed significant alterations of genes and pathways in a pattern consistent with previous microarray studies of autism spectrum disorder patients. Moreover, expression analysis revealed copy number-dependent increased messenger RNA (mRNA) levels in affected patients compared to control individuals. A subset of differentially expressed genes was validated using qRT-PCR. INTERPRETATION: Xq12-q13.3 duplication is a novel global developmental delay and autism-predisposing chromosomal aberration; pathogenesis of which may be mediated by increased dosage of genes contained in the duplication, including NLGN3, OPHN1, AR, EFNB1, TAF1, GJB1, and MED12.

Mutation of TBCE causes hypoparathyroidism-retardation-dysmorphism and autosomal recessive Kenny-Caffey syndrome.

The syndrome of congenital hypoparathyroidism, mental retardation, facial dysmorphism and extreme growth failure (HRD or Sanjad-Sakati syndrome; OMIM 241410) is an autosomal recessive disorder reported almost exclusively in Middle Eastern populations. A similar syndrome with the additional features of osteosclerosis and recurrent bacterial infections has been classified as autosomal recessive Kenny-Caffey syndrome (AR-KCS; OMIM 244460). Both traits have previously been mapped to chromosome 1q43-44 (refs 5,6) and, despite the observed clinical variability, share an ancestral haplotype, suggesting a common founder mutation. We describe refinement of the critical region to an interval of roughly 230 kb and identification of deletion and truncation mutations of TBCE in affected individuals. The gene TBCE encodes one of several chaperone proteins required for the proper folding of alpha-tubulin subunits and the formation of alpha-beta-tubulin heterodimers. Analysis of diseased fibroblasts and lymphoblastoid cells showed lower microtubule density at the microtubule-organizing center (MTOC) and perturbed microtubule polarity in diseased cells. Immunofluorescence and ultrastructural studies showed disturbances in subcellular organelles that require microtubules for membrane trafficking, such as the Golgi and late endosomal compartments. These findings demonstrate that HRD and AR-KCS are chaperone diseases caused by a genetic defect in the tubulin assembly pathway, and establish a potential connection between tubulin physiology and the development of the parathyroid.

Mutations in C2orf37, encoding a nucleolar protein, cause hypogonadism, alopecia, diabetes mellitus, mental retardation, and extrapyramidal syndrome.

Hypogonadism, alopecia, diabetes mellitus, mental retardation, and extrapyramidal syndrome (also referenced as Woodhouse-Sakati syndrome) is a rare autosomal recessive multisystemic disorder. We have identified a founder mutation consisting of a single base-pair deletion in C2orf37 in eight families of Saudi origin. Three other loss-of-function mutations were subsequently discovered in patients of different ethnicities. The gene encodes a nucleolar protein of unknown function, and the cellular phenotype observed in patient lymphoblasts implicates a role for the nucleolus in the pathogenesis of this disease. Our findings expand the list of human disorders linked to the nucleolus and further highlight the developmental and/or maintenance functions of this organelle.

Dyggve-Melchior-Clausen syndrome: novel splice mutation with atlanto-axial subluxation.

Dyggve-Melchior-Clausen (DMC) syndrome is a rare autosomal recessive disorder characterized by the association of a progressive spondyloepimetaphyseal dysplasia and mental retardation ranging from mild to severe. The disorder results from mutations in the dymeclin (DYM) gene in the 18q12-12.1 chromosomal region. We report two siblings with classical clinical and radiological features of DMC and asymptomatic atlanto-axial dislocation. A novel homozygous splice-site mutation (IVS15+3G>T) was detected. Reverse transcriptase polymerase chain reaction (RT-PCR) confirmed that this mutation affects normal splicing. To the best of our knowledge, this is the first report of DMC from Saudi Arabia. The splice mutation noted in our patients was compared to the previously reported cases and supports the hypothesis that loss of DYM function is the likely mechanism of disease pathogenesis. In conclusion, distinction between this type of skeletal dysplasia and Morquio disease (MPS IV) is important for paediatricians and clinical geneticist in providing standard patient care and genetic counselling.

25-Hydroxylase vitamin D deficiency in 27 Saudi Arabian subjects: a clinical and molecular report on CYP2R1 mutations.

Vitamin D deficiency remains a major cause of rickets worldwide. Nutritional factors are the major cause and less commonly, inheritance causes. Recently, CYP2R1 has been reported as a major factor for 25-hydroxylation contributing to the inherited forms of vitamin D deficiency. We conducted a prospective cohort study at King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia, to review cases with 25-hydroxylase deficiency and describe their clinical, biochemical, and molecular genetic features. We analyzed 27 patients from nine different families who presented with low 25-OH vitamin D and not responding to usual treatment. Genetic testing identified two mutations: c.367+1G>A (12/27 patients) and c.768dupT (15/27 patients), where 18 patients were homozygous for their identified mutation and 9 patients were heterozygous. Both groups had similar clinical manifestations ranging in severity, but none of the patients with the heterozygous mutation had hypocalcemic manifestations. Thirteen out of 18 homozygous patients and all the heterozygous patients responded to high doses of vitamin D treatment, but they regressed after decreasing the dose, requiring lifelong therapy. Five out of 18 homozygous patients required calcitriol to improve their biochemical data, whereas none of the heterozygous patients and patients who carried the c.367+1G>A mutation required calcitriol treatment. To date, this is the largest cohort series analyzing CYP2R1-related 25-hydroxylase deficiency worldwide, supporting its major role in 25-hydroxylation of vitamin D. It is suggested that a higher percentage of CYP2R1 mutations might be found in the Saudi population. We believe that our study will help in the diagnosis, treatment, and prevention of similar cases in the future.

Identification of Novel CDH23 Variants Causing Moderate to Profound Progressive Nonsyndromic Hearing Loss.

Mutant alleles of CDH23, a gene that encodes a putative calcium-dependent cell-adhesion glycoprotein with multiple cadherin-like domains, are responsible for both recessive DFNB12 nonsyndromic hearing loss (NSHL) and Usher syndrome 1D (USH1D). The encoded protein cadherin 23 (CDH23) plays a vital role in maintaining normal cochlear and retinal function. The present study's objective was to elucidate the role of DFNB12 allelic variants of CDH23 in Saudi Arabian patients. Four affected offspring of a consanguineous family with autosomal recessive moderate to profound NSHL without any vestibular or retinal dysfunction were investigated for molecular exploration of genes implicated in hearing impairment. Parallel to this study, we illustrate some possible pitfalls that resulted from unexpected allelic heterogeneity during homozygosity mapping due to identifying a shared homozygous region unrelated to the disease locus. Compound heterozygous missense variants (p.(Asp918Asn); p.(Val1670Asp)) in CDH23 were identified in affected patients by exome sequencing. Both the identified missense variants resulted in a substitution of the conserved residues and evaluation by multiple in silico tools predicted their pathogenicity and variable disruption of CDH23 domains. Three-dimensional structure analysis of human CDH23 confirmed that the residue Asp918 is located at a highly conserved DXD peptide motif and is directly involved in "Ca2+" ion contact. In conclusion, our study identifies pathogenic CDH23 variants responsible for isolated moderate to profound NSHL in Saudi patients and further highlights the associated phenotypic variability with a genotypic hierarchy of CDH23 mutations. The current investigation also supports the application of molecular testing in the clinical diagnosis and genetic counseling of hearing loss.

First report of two successive deletions on chromosome 15q13 cytogenetic bands in a boy and girl: additional data to 15q13.3 syndrome with a report of high IQ patient.

15q13.3 syndrome is associated with a wide spectrum of neurological disorders. Among a cohort of 150 neurodevelopmental cases, we identified two patients with two close proximity interstitial hemizygous deletions on chromosome 15q13. Using high-density microarrays, we characterized these deletions and their approximate breakpoints. The second deletion in both patients overlaps in a small area containing CHRNA7 where the gene is partially deleted. The CHRNA7 is considered a strong candidate for the 15q13.3 deletion syndrome's pathogenicity. Patient 1 has cognitive impairment, learning disabilities, hyperactivity and subtle dysmorphic features whereas patient 2 has mild language impairment with speech difficulty, mild dysmorphia, heart defect and interestingly a high IQ that has not been reported in 15q13.3 syndrome patients before. Our study presents first report of such two successive deletions in 15q13.3 syndrome patients and a high IQ in a 15q13.3 syndrome patient. Our study expands the breakpoints and phenotypic features related to 15q13.3 syndrome.

Genome-wide gene expression profiling and mutation analysis of Saudi patients with Canavan disease.

PURPOSE: Canavan disease, caused by a deficiency of aspartoacylase, is one of the most common cerebral degenerative diseases of infancy. The aims of this study were to identify the mutations associated with Canavan disease in Saudi Arabia and to identify differentially expressed genes likely to contribute to the development of this disease. METHODS: Polymerase chain reaction, long polymerase chain reaction, multiplex ligation-dependent probe amplification, sequencing, array comparative genomic hybridization (aCGH), and global gene expression profiling were used to determine putative mutations and likely gene signatures in cultured fibroblasts of patients from Saudi Arabia. RESULTS: One novel and one known large deletion and two previously known mutations (IVS4 + 1G>T and G27R) were identified. Compared with controls, 1440 genes were significantly modulated in Canavan patients (absolute fold change [FC] > or =4). Genome-wide gene expression profiling results indicated that some genes, involved in apoptosis, muscle contraction and development, mitochondrial oxidation, inflammation and glutamate, and aspartate metabolism, were significantly dysregulated. CONCLUSIONS: Our findings indicate that the presence of muscle weakness and hypotonia in patients may be associated with the dysregulated gene activities of cell motility, muscle contraction and development, actin binding, and cytoskeletal-related activities. Overall, these observations are in accordance with previous studies performed in a knockout mouse model.

Type I congenital multiple intraspinal extradural cysts associated with distichiasis and lymphedema syndrome.

OBJECTIVE: The hereditary syndrome of multiple congenital intraspinal cysts associated with distichiasis, lymphedema and other congenital deformities is extremely rare. Modern imaging techniques have promoted the non-invasive diagnosis of spinal pathology and paved the way for better surgical planning. We reviewed the clinical data, imaging studies and treatment outcomes of a 12-year-old boy with this syndrome. CLINICAL PRESENTATION: Progressive spastic paraparesis with signs of spinal cord compression leading to frequent falls. This was associated with bilateral double row of eyelashes and pretibial edema. The MRI of thoracic spine depicted two large elongated extradural lesions extending from D5-D10 with signal intensity compatible with cerebrospinal fluid leading to severe compression of the spinal cord dorsally. TREATMENT: Laminotomy and complete microsurgical excision of the cysts resulted in a fast and full clinical recovery of his neurological deficit. CONCLUSION: Type I congenital intraspinal cysts is a rare etiology of cord compression syndrome and may be associated with distichiasis, lymphedema and other congenital deformaties. It has several characteristics, which include the higher incidence in thoracic spine and younger age group, disproportional sever motor deficit as compared with sensory disturbances and the excellent clinical recovery following successful surgical treatment.

Persistent hyperinsulinaemic hypoglycaemia of infancy in 43 children: long-term clinical and surgical follow-up.

OBJECTIVE: To describe the clinical, surgical, biochemical, radiological and electrophysiological features of 43 Saudi children with persistent hyperinsulinaemic hypoglycaemia of infancy (PHHI) who have been followed since 1983. METHODS: Data from 43 patients were retrospectively analysed. PHHI was diagnosed on the basis of high intravenous glucose requirement, high insulin to glucose ratio, negative urinary ketones and normal tandem mass spectrometry. The patients were assessed radiologically by brain magnetic resonance imaging and/or computed tomography and electrophysiologically by brain stem auditory evoked potential, visual evoked response and electroencephalogram. Patients who failed medical therapy received near total pancreatectomy. RESULTS: The patients were severely hypoglycaemic and intolerant to fast. Hypoglycaemic convulsion was the most commonly presenting complaint. Eighteen patients were developmentally delayed and 14 of them had brain atrophy. All patients, except nine, did not respond to medical treatment and underwent surgery. Four pancreatectomized patients developed diabetes and two had malabsorption. One baby had 180 cm resection of gangrenous bowel most likely secondary to octreotide. No common bile duct injury was encountered. One patient was treated medically during childhood and developed diabetes and gained weight during adolescence. CONCLUSION: PHHI is a relatively common and serious disease among Saudi children. Early intervention is necessary to avoid neurological damage in patients who are severely hypoglycaemic and unresponsive to medical therapy. Surgically and probably medically treated patients are at a high risk of developing diabetes, which could be the natural outcome of this disease. Care and spending time during surgery to visualize the common bile duct help in avoiding its injury.

Diabetes mellitus and cystic fibrosis in 2 Saudi siblings.

Diabetes mellitus and cystic fibrosis (CF) have been reported before in the literature, but they have never been reported in the same patient in the Middle East. We present the first reported case of insulin dependent diabetes mellitus (IDDM) and CF in 2 siblings of the same family. Both siblings were diagnosed early in life with IDDM, and their diabetes was well controlled on insulin. Cystic fibrosis was diagnosed in the first case one year after IDDM was diagnosed due to history of chronic cough and in the 2nd case by family screening. Both had severe failure to thrive, recurrent chest infections and gastro-esophageal reflux. With treatment both showed clinical improvement, but continued to have moderate lung disease radiologically and by pulmonary function test.

Long-term follow up of carbonic anhydrase II deficiency syndrome.

OBJECTIVE: To describe the long term clinical, biochemical and radiological features of 35 Saudi Arabian children with carbonic anhydrase II deficiency syndrome who have been followed at King Faisal Specialist Hospital and Research Center, Riyadh since 1979. METHODS: The records of these patients were retrospectively evaluated. The diagnosis was based on the clinical and the radiological evidence of the disease. Carbonic anhydrase II level was measured in 9 patients. RESULTS: Clinically, these patients had typical facial features, growth failure and varying degrees of psychomotor retardation. Biochemically, all children had renal tubular acidosis that was of distal type in the majority of them. Radiologically, this syndrome was characterized by metyphyseal osteopetrosis and intracranial calcification that was progressive in 2 patients. Five patients were blind secondary to optic nerve entrapment and 2 patients developed anemia and secondary erythropoesis due to bone marrow involvement. Nineteen patients had attained the final adult height; the mean adult height was 146 cm (-3 standard deviation) in 11 females and 152 cm (-4 standard deviation) in 8 males. Two patients were married and had clinically and radiologically normal children. CONCLUSION: The syndrome of carbonic anhydrase II deficiency is usually benign in nature and compatible with long term survival, however it can progress and involve the cranial nerves. Close clinical and neurological assessment of these patients is mandatory to early detect and manage potential serious complications.

Persistent hyperinsulinemic hypoglycemia of infancy in 38 children.

OBJECTIVE: To describe the clinical, biochemical, radiological and electrophysiological features of 38 Saudi children with persistent hyperinsulinemic hypoglycemia of infancy that have been followed since 1983. METHODS: Data from 38 patients followed at King Faisal Specialist Hospital and Research Centre, Riyadh, Kingdom of Saudi Arabia from 1983 through to 2002 was retrospectively analyzed. Persistent hyperinsulinemic hypoglycemia of infancy was diagnosed on the basis of high intravenous glucose requirement, high insulin to glucose ratio, negative urinary ketones and normal tandem mass spectrometry. The patients were assessed radiologically by brain magnetic resonance imaging, computed tomography, or both and electrophysiologically by brain stem auditory evoked potential, visual evoked response and electroencephalogram. The patients who failed medical therapy had subtotal pancreatectomy. RESULTS: The patients were severely hypoglycemic and intolerant to fast. Hypoglycemic convulsion was the most commonly presenting complaint. Eighteen patients were developmentally delayed and 14 of them had brain atrophy. All patients, except nine, did not respond to medical treatment and had surgery. Four pancreatectomized patients developed diabetes and 2 had malabsorption. One patient was treated medically during childhood and developed diabetes and weight gain during adolescence. CONCLUSION: Persistent hyperinsulinemic hypoglycemia of infancy is a relatively common and serious disease among Saudi children. Early medical intervention is necessary to avoid neurological damage in our patients who are severely hypoglycemic and medical therapy unresponsive. Surgically and probably medically treated patients are at high risk of developing diabetes that could be the natural outcome of this disease.

Prevalence and characteristics of celiac disease in type I diabetes mellitus in Saudi Arabia.

OBJECTIVE: To examine the prevalence of celiac disease in young patients in the Kingdom of Saudi Arabia with type I diabetes mellitus. METHODS: Serum gliadin immunoglobulin (Ig) A and reticulin IgA antibody determination was performed in 123 patients with type I diabetes mellitus attending the pediatric diabetic clinic at King Faisal Specialist Hospital and Research Centre, Riyadh, Kingdom of Saudi Arabia between 1995 and 1996. RESULTS: Elevated serum gliadin and reticulin IgA antibodies were found in the sera of 10 (8.1%) of the 123 diabetic children; none had gastrointestinal symptoms. Six of the 10 subjects had jejunal biopsy, which showed total villus atrophy. Four subjects did not undergo jejunal biopsy. The gender ratio of the biopsy positive is 5 male:1 female. All subjects with IgA positive were put on gluten free diet and normalized in a few months. CONCLUSION: The maximum prevalence of celiac disease in our population was 8.1% based on immunological marker and the minimum was 4.9% based on antibodies and biopsy results.

The syndrome of septo-optic dysplasia in Saudi children.

OBJECTIVE: To describe the clinical, ophthalmological, endocrinological and radiological features of 10 Saudi children with the syndrome of septo-optic dysplasia and hypothalamic hypopituitarism. METHODS: All patients underwent complete ophthalmological and endocrinological evaluation at the Pediatric Endocrine Clinics, King Faisal Specialist Hospital and Research Center and King Fahad National Guard Hospital, Riyadh, Kingdom of Saudi Arabia, from October 1999 through to May 2004. The hormonal evaluation included growth hormone, adrenocorticotrophic hormone, thyroid stimulating hormone, gonadotropin and anti diuretic hormone testing, and the neuroradiological assessment included brain magnetic resonance imaging or computed tomogram scanning, or both. RESULTS: The current age of patients ranged from 18- months to 5-years. The mean age of initial presentation for endocrine evaluation was 14-months. Hormonal studies indicated that all children had multiple pituitary hormone deficiencies (2 or more of the pituitary hormones were deficient). Ten children had growth hormone deficiency, 8 had thyroid stimulating hormone deficiency, 8 had adrenocorticotrophic hormone deficiency, 2 children were suspected to have gonadotropin deficiency and central diabetes insipidus was present in one patient. Pendular nystagmus and impaired vision were common initial signs. All children had bilateral optic nerve hypoplasia. Neuroradiologic findings were variable. Eight children had absent septum pellucidum, 3 had pituitary gland hypoplasia, 2 had pituitary stalk dysplasia (pituitary stalk was either attenuated or not visualized), 2 had absent corpus callosum and one had absent posterior pituitary high intensity signal. All patients were replaced with appropriate hormonal replacement therapy. Two male children had micropenis which responded to testosterone therapy. CONCLUSION: The syndrome of septo-optic dysplasia is commonly associated with hypothalamic hypopituitarism including anterior and posterior pituitary hormonal deficiencies. Early diagnosis of this syndrome is critical as the hormonal deficiencies can be life threatening.