Experts' Opinion in Fabry Disease Management and the Unmet Medical Need: The Saudi Perspective.

Fabry disease (FD) is an X-linked lysosomal storage disorder caused by α-galactosidase A gene mutations. Its global incidence ranges from 1:40,000 to 1:170,000. This expert review evaluates the available guidelines, the status of diagnosed but untreated patients with FD, and the challenges in diagnosing and managing FD in the Kingdom of Saudi Arabia (KSA).

Consensus-based expert recommendations on the management of MPS IVa and VI in Saudi Arabia.

Background: Mucopolysaccharidosis type IVa (Morquio A syndrome) and mucopolysaccharidosis type VI (Maroteaux-Lamy syndrome) are rare inherited lysosomal storage diseases associated with significant functional impairment and a wide spectrum of debilitating clinical manifestations. These conditions are thought to have higher-than-average prevalence rates in Saudi Arabia due to high rates of consanguineous marriage in the country. There are several unmet needs associated with the management of these diseases in Saudi Arabia.

BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening.

There are few causes of treatable neurodevelopmental diseases described to date. Branched-chain ketoacid dehydrogenase kinase (BCKDK) deficiency causes branched-chain amino acid (BCAA) depletion and is linked to a neurodevelopmental disorder characterized by autism, intellectual disability and microcephaly. We report the largest cohort of patients studied, broadening the phenotypic and genotypic spectrum.

Immune dysregulation caused by homozygous mutations in CBLB.

CBL-B is an E3 ubiquitin ligase that ubiquitinates proteins downstream of immune receptors to downregulate positive signaling cascades. Distinct homozygous mutations in CBLB were identified in 3 unrelated children with early-onset autoimmunity, one of whom also had chronic urticaria. Patient T cells exhibited hyperproliferation in response to anti-CD3 cross-linking.

Loss of FOCAD, operating via the SKI messenger RNA surveillance pathway, causes a pediatric syndrome with liver cirrhosis.

Cirrhosis is usually a late-onset and life-threatening disease characterized by fibrotic scarring and inflammation that disrupts liver architecture and function. While it is typically the result of alcoholism or hepatitis viral infection in adults, its etiology in infants is much less understood. In this study, we report 14 children from ten unrelated families presenting with a syndromic form of pediatric liver cirrhosis.

Biallelic Variants in the Ectonucleotidase ENTPD1 Cause a Complex Neurodevelopmental Disorder with Intellectual Disability, Distinct White Matter Abnormalities, and Spastic Paraplegia.

Objective: Human genomics established that pathogenic variation in diverse genes can underlie a single disorder. For example, hereditary spastic paraplegia is associated with >80 genes, with frequently only few affected individuals described for each gene. Herein, we characterize a large cohort of individuals with biallelic variation in ENTPD1, a gene previously linked to spastic paraplegia 64 (Mendelian Inheritance in Man # 615683).

A Human Pleiotropic Multiorgan Condition Caused by Deficient Wnt Secretion.

Background: Structural birth defects occur in approximately 3% of live births; most such defects lack defined genetic or environmental causes. Despite advances in surgical approaches, pharmacologic prevention remains largely out of reach.

Methods: We queried worldwide databases of 20,248 families that included children with neurodevelopmental disorders and that were enriched for parental consanguinity.

Combining exome/genome sequencing with data repository analysis reveals novel gene-disease associations for a wide range of genetic disorders.

Purpose: Within this study, we aimed to discover novel gene-disease associations in patients with no genetic diagnosis after exome/genome sequencing (ES/GS).

Methods: We followed two approaches: (1) a patient-centered approach, which after routine diagnostic analysis systematically interrogates variants in genes not yet associated to human diseases; and (2) a gene variant centered approach. For the latter, we focused on de novo variants in patients that presented with neurodevelopmental delay (NDD) and/or intellectual disability (ID), which are the most common reasons for genetic testing referrals.

SCUBE3 loss-of-function causes a recognizable recessive developmental disorder due to defective bone morphogenetic protein signaling.

Signal peptide-CUB-EGF domain-containing protein 3 (SCUBE3) is a member of a small family of multifunctional cell surface-anchored glycoproteins functioning as co-receptors for a variety of growth factors. Here we report that bi-allelic inactivating variants in SCUBE3 have pleiotropic consequences on development and cause a previously unrecognized syndromic disorder. Eighteen affected individuals from nine unrelated families showed a consistent phenotype characterized by reduced growth, skeletal features, distinctive craniofacial appearance, and dental anomalies.

Successful application of genome sequencing in a diagnostic setting: 1007 index cases from a clinically heterogeneous cohort.

Despite clear technical superiority of genome sequencing (GS) over other diagnostic methods such as exome sequencing (ES), few studies are available regarding the advantages of its clinical application. We analyzed 1007 consecutive index cases for whom GS was performed in a diagnostic setting over a 2-year period. We reported pathogenic and likely pathogenic (P/LP) variants that explain the patients' phenotype in 212 of the 1007 cases (21.

Biallelic inactivating variants in the GTPBP2 gene cause a neurodevelopmental disorder with severe intellectual disability.

Congenital neurological disorders are genetically highly heterogeneous. Rare forms of hereditary neurological disorders are still difficult to be adequately diagnosed. Pertinent studies, especially when reporting only single families, need independent confirmation.

The clinical and genetic Spectrum of Maroteaux-Lamy syndrome (Mucopolysaccharidosis VI) in the Eastern Province of Saudi Arabia.

Mucopolysaccharidosis (MPS VI) or Maroteaux-Lamy syndrome is an autosomal recessive lysosomal storage disease caused by deficiency of the enzyme N-acetylgalactosamine 4-sulfatase or arylsulfatase B. It is involved in the degradation of glycosaminoglycans and characterized by a wide spectrum of clinical and genetic heterogeneity. So far, more than 150 mutations have been reported in the ARSB gene.

AMPA-receptor specific biogenesis complexes control synaptic transmission and intellectual ability.

AMPA-type glutamate receptors (AMPARs), key elements in excitatory neurotransmission in the brain, are macromolecular complexes whose properties and cellular functions are determined by the co-assembled constituents of their proteome. Here we identify AMPAR complexes that transiently form in the endoplasmic reticulum (ER) and lack the core-subunits typical for AMPARs in the plasma membrane. Central components of these ER AMPARs are the proteome constituents FRRS1l (C9orf4) and CPT1c that specifically and cooperatively bind to the pore-forming GluA1-4 proteins of AMPARs.

Clinical exome sequencing: results from 2819 samples reflecting 1000 families.

We report our results of 1000 diagnostic WES cases based on 2819 sequenced samples from 54 countries with a wide phenotypic spectrum. Clinical information given by the requesting physicians was translated to HPO terms. WES processes were performed according to standardized settings.

Diagnosis and treatment of late-onset Pompe disease in the Middle East and North Africa region: consensus recommendations from an expert group.

Background: Pompe disease is a rare autosomal recessive disorder caused by a deficiency of the lysosomal enzyme alpha-glucosidase responsible for degrading glycogen. Late-onset Pompe disease has a complex multisystem phenotype characterized by a range of symptoms.

Methods: An expert panel from the Middle East and North Africa (MENA) region met to create consensus-based guidelines for the diagnosis and treatment of late-onset Pompe disease for the MENA region, where the relative prevalence of Pompe disease is thought to be high but there is a lack of awareness and diagnostic facilities.

Early treatment with laronidase improves clinical outcomes in patients with attenuated MPS I: a retrospective case series analysis of nine sibships.

Background: Enzyme replacement therapy (ERT) with laronidase, (recombinant human α-L-iduronidase; Aldurazyme) is the primary treatment option for patients with attenuated mucopolysaccharidosis type I (MPS I). This study examined the effect of early ERT on clinical manifestations.

Methods: This multinational, retrospective case series abstracted data from records of 20 patients with Hurler-Scheie syndrome within nine sibships that included older siblings treated with laronidase after the development of significant clinical symptoms, and younger siblings treated before significant symptomatology.

Nail-Patella Syndrome: A Report of a Saudi Arab Family With an Autosomal Recessive Inheritance.

Background: Nail-patella syndrome (NPS) is an autosomal dominant disorder with a variable interfamilial and intrafamilial clinical expressivity and penetrance. It is caused by loss-of-function heterozygous mutation in the LIM-homeodomain transcription factor (LMX1B) located on chromosome 9q. The pleiotropic LMB1X gene, a member of the homeogene family, is involved in the development of glomerular basement membrane, dorsoventral limb structures, along with the nails and the anterior segment of the eye.

Accelerating novel candidate gene discovery in neurogenetic disorders via whole-exome sequencing of prescreened multiplex consanguineous families.

Our knowledge of disease genes in neurological disorders is incomplete. With the aim of closing this gap, we performed whole-exome sequencing on 143 multiplex consanguineous families in whom known disease genes had been excluded by autozygosity mapping and candidate gene analysis. This prescreening step led to the identification of 69 recessive genes not previously associated with disease, of which 33 are here described (SPDL1, TUBA3E, INO80, NID1, TSEN15, DMBX1, CLHC1, C12orf4, WDR93, ST7, MATN4, SEC24D, PCDHB4, PTPN23, TAF6, TBCK, FAM177A1, KIAA1109, MTSS1L, XIRP1, KCTD3, CHAF1B, ARV1, ISCA2, PTRH2, GEMIN4, MYOCD, PDPR, DPH1, NUP107, TMEM92, EPB41L4A, and FAM120AOS).

A homozygous double mutation in SMN1: a complicated genetic diagnosis of SMA.

Spinal muscular atrophy (SMA), the most common autosomal recessive cause of infant death, is typically diagnosed by determination of SMN1 copy number. Approximately 3-5% of patients with SMA retain at least one copy of the SMN1 gene carrying pathogenic insertions, deletions, or point mutations. We report a patient with SMA who is homozygous for two mutations carried in cis: an 8 bp duplication (c.