Genetic Causes, Clinical Features, and Survival of Underlying Inborn Errors of Immunity in Omani Patients: a Single-Center Study.

PURPOSE: Early identification of inborn errors of immunity (IEIs) is crucial due to the significant risk of morbidity and mortality. This study aimed to describe the genetic causes, clinical features, and survival rate of IEIs in Omani patients. METHODS: A prospective study of all Omani patients evaluated for immunodeficiency was conducted over a 17-year period. Clinical features and diagnostic immunological findings were recorded. Targeted gene testing was performed in cases of obvious immunodeficiency. For cases with less conclusive phenotypes, a gene panel was performed, followed by whole-exome sequencing if necessary. RESULTS: A total of 185 patients were diagnosed with IEIs during the study period; of these, 60.5% were male. Mean ages at symptom onset and diagnosis were 30.0 and 50.5 months, respectively. Consanguinity and a family history of IEIs were present in 86.9% and 50.8%, respectively. Most patients presented with lower respiratory infections (65.9%), followed by growth and development manifestations (43.2%). Phagocytic defects were the most common cause of IEIs (31.9%), followed by combined immunodeficiency (21.1%). Overall, 109 of 132 patients (82.6%) who underwent genetic testing received a genetic diagnosis, while testing was inconclusive for the remaining 23 patients (17.4%). Among patients with established diagnoses, 37 genes and 44 variants were identified. Autosomal recessive inheritance was present in 81.7% of patients with gene defects. Several variants were novel. Intravenous immunoglobulin therapy was administered to 39.4% of patients and 21.6% received hematopoietic stem cell transplantation. The overall survival rate was 75.1%. CONCLUSION: This study highlights the genetic causes of IEIs in Omani patients. This information may help in the early identification and management of the disease, thereby improving survival and quality of life.

Shohat type-spondyloepimetaphyseal dysplasia: Further phenotypic delineation.

Spondyloepimetaphyseal dysplasia-Shohat type (SEMDSH) is an ultra-rare type of skeletal dysplasia. Only nine patients from six families have been reported and genetically confirmed to have biallelic pathogenic variants in the DDRGK1 gene. We present a patient with typical clinical features of the disorder, including disproportionate short-limbed short stature, short neck, short chest with pectus carinatum, exaggerated lumbar lordosis and marked genu vara. Our patient further showed microcephaly, unilateral choanal atresia and antenatal fractures, features that were not reported before in association with this disorder. Radiological changes over time were presented, including delayed epiphyseal ossification, broad metaphysis with marked irregularities that progressed with age, fibular overgrowth, and characteristic spine changes with early platyspondyly and squaring of vertebral bodies at a later age. Exome sequencing revealed a homozygous pathogenic donor splice site variant in the DDRGK1 gene (NM_023935.3:c.408+1G > A). This mutation was also previously identified in patients from Iraqi descent. Our study expands the phenotypic spectrum of SEMDSH, emphasizes the radiological changes with age in SEMDSH patients, and recommends prolonged follow-up for these cases better to delineate the phenotype and surveillance for possible complications.

BCL10 loss-of-function novel mutation leading to atypical severe combined immunodeficiency.

BACKGROUND: Severe combined immunodeficiency (SCID) is characterized by severe, early-onset infection in infants. B-cell lymphoma/leukemia (BCL) 10 defects causing SCID have been reported previously in two patients. MATERIAL & METHODS: A seven-month-old female infant was admitted with bilateral pneumonia requiring ventilatory support. She had a history of recurrent infections starting from four months of age. The patient was investigated for primary immunodeficiency. RESULTS: Immunological investigations revealed hypogammaglobulinemia with normal CD4 and CD8 lymphocyte counts, while a lymphocyte proliferation assay showed absent response to phytohemagglutinin stimulation, thereby establishing the diagnosis of an atypical form of SCID. Genetic testing revealed a homozygous mutation in the BCL10 gene, with both parents demonstrating a heterozygous state (NM_003921.5:c.271A > C:p.[Thr91Pro]). The patient died before bone marrow transplantation due to severe disseminated adenovirus disease. CONCLUSION: We report the first patient from the Middle East with a novel homozygous mutation in the BCL10 gene causing SCID.

Recessive PRDM13 mutations cause fatal perinatal brainstem dysfunction with cerebellar hypoplasia and disrupt Purkinje cell differentiation.

Pontocerebellar hypoplasias (PCHs) are congenital disorders characterized by hypoplasia or early atrophy of the cerebellum and brainstem, leading to a very limited motor and cognitive development. Although over 20 genes have been shown to be mutated in PCHs, a large proportion of affected individuals remains undiagnosed. We describe four families with children presenting with severe neonatal brainstem dysfunction and pronounced deficits in cognitive and motor development associated with four different bi-allelic mutations in PRDM13, including homozygous truncating variants in the most severely affected individuals. Brain MRI and fetopathological examination revealed a PCH-like phenotype, associated with major hypoplasia of inferior olive nuclei and dysplasia of the dentate nucleus. Notably, histopathological examinations highlighted a sparse and disorganized Purkinje cell layer in the cerebellum. PRDM13 encodes a transcriptional repressor known to be critical for neuronal subtypes specification in the mouse retina and spinal cord but had not been implicated, so far, in hindbrain development. snRNA-seq data mining and in situ hybridization in humans show that PRDM13 is expressed at early stages in the progenitors of the cerebellar ventricular zone, which gives rise to cerebellar GABAergic neurons, including Purkinje cells. We also show that loss of function of prdm13 in zebrafish leads to a reduction in Purkinje cells numbers and a complete absence of the inferior olive nuclei. Altogether our data identified bi-allelic mutations in PRDM13 as causing a olivopontocerebellar hypoplasia syndrome and suggest that early deregulations of the transcriptional control of neuronal fate specification could contribute to a significant number of cases.

The Pediatric Cerebellum in Inherited Neurodegenerative Disorders: A Pattern-recognition Approach.

Evaluation of imaging studies of the cerebellum in inherited neurodegenerative disorders is aided by attention to neuroimaging patterns based on anatomic determinants, including biometric analysis, hyperintense signal of structures, including the cerebellar cortex, white matter, dentate nuclei, brainstem tracts, and nuclei, the presence of cysts, brain iron, or calcifications, change over time, the use of diffusion-weighted/diffusion tensor imaging and T2*-weighted sequences, magnetic resonance spectroscopy; and, in rare occurrences, the administration of contrast material.

A novel CASR mutation associated with neonatal severe hyperparathyroidism transmitted as an autosomal recessive disorder.

BACKGROUND: Neonatal severe primary hyperparathyroidism (NSHPT, MIM 239200) is most often an isolated disorder that is due to biallelic inactivating mutations in the CASR, the gene encoding the calcium sensing receptor; NSHPT is inherited from parents with familial hypocalciuric hypercalcemia, each of whom has one mutated CASR allele. OBJECTIVES: To report clinical and genetic findings in a brother and sister with NSHPT due to a novel mutation in the CASR transmitted as an autosomal recessive trait and to examine the functional effect of the mutation. SUBJECTS AND METHODS: A brother and sister with marked hypercalcemia due to NSHPT were identified; the boy also had craniosynostosis requiring surgical repair. The genotyping of the CASR in both children and their parents who were eucalcemic and normophosphatemic was undertaken. In order to examine the significance of the variant CASR identified, the CASR variant was expressed in vitro and examined by three computer computational programs [PolyPhen2, MutationTaster, Sorting Intolerant From Tolerant (SIFT)] designed to evaluate the effect of a nucleotide variant on the structure and likely functional consequence upon the protein product. RESULTS: A sequence variant in the CASR was identified [G>T point mutation at nucleotide c.2303 in exon 7 (c.2303G>T) resulting in the replacement of glycine by valine at codon 768 (p.Gly768Val)]. Two copies of this CASR variant were present in the genome of the siblings while a single copy of the CASR variant was present in both of the clinically and biochemically normal parents, a pattern of transmission consistent with autosomal recessive inheritance of NSHPT in this family. When expressed in HEK293 cells in vitro, the novel Gly768Val variant did not interfere with protein generation or migration to the cell membrane in vitro. The analysis of the functional effect of the Gly768Val CASR variant by the PolyPhen2, MutationTaster, and Sorting Intolerant From Tolerant computer programs revealed that this mutation was very likely to be deleterious. CONCLUSION: The NSHPT associated with biallelic Gly768Val mutations of the CASR in two siblings with severe hypercalcemia and hyperparathyroidism and their clinically and biochemically normal heterozygous parents was transmitted as an autosomal recessive disorder in this family.

Clinical characteristics in patients with interstitial deletions of chromosome region 12q21-q22 and identification of a critical region associated with keratosis pilaris.

We report on a male patient with a submicroscopic 1.21 Mb de novo deletion at 12q21.33-q22 with global developmental delay, characteristic facial features, and keratosis pilaris. Thus far, five other cases with a 12q de novo deletion including this segment have been reported; our case represents the smallest de novo deletion within this chromosome region. High resolution SNP microarray analysis showed a deletion of RefSeq genes BTG1 and LOC256021, and partial deletion of DCN. We propose that BTG1 is a critical gene for the development of the distinctive keratosis pilaris observed in patients with interstitial deletion of 12q21-q22, and suggest candidate genes that may contribute to dysmorphic features and global developmental delay.

Merosin-deficient congenital muscular dystrophy in an Omani boy.

Merosin-deficient congenital muscular dystrophy is an autosomal recessive disease that can manifest differently in different ethnic groups. This often presents as a floppy infant, and normal mental development. The creatine kinase is usually elevated with white matter abnormalities on brain imaging. In this report, we describe an infant with Merosin-deficient congenital muscular dystrophy who presented with delayed motor milestones and hypotonia. The clinical features, biopsy findings, and neuroimaging abnormalities in our patient are described.