Novel UBE3B mutations: report of eight patients with Kaufman oculocerebrofacial syndrome with additional clinical findings from a highly consanguineous population.

Biallelic mutations in UBE3B cause Kaufman oculocerebrofacial syndrome (KOS; OMIM 244450) with a wide range of clinical manifestations. In this study, we employed genetic analyses including homozygosity mapping, candidate gene sequencing, whole exome sequencing, and confirmatory Sanger sequencing on eight patients from three unrelated consanguineous families. Our analysis yielded three different novel variants in UBE3B : a missense substitution [NM_130466.4: c.2975C>T; (p.Pro992Leu)] in the HECT domain in family 1, a 3-bp deletion within exon 14 [c.1692_1694delCTC; (p.Ser565del)] leading to removal of a serine residue in family 2, and a splice donor site variant in intron eight of UBE3B (c.630 + 1G>T) in family 3. Blepharophimosis, telecanthus, ptosis, intellectual disability and abnormal lipid profile were similar to those found in previously reported KOS patients. Longitudinal follow-up revealed rather marfanoid body habitus of the patients in family 1. This study reports eight patients from Saudi Arabia with novel deleterious variants in UBE3B and adds to the phenotypic spectrum of KOS.

Expanding the phenotypic and genotypic spectrum of GGPS1 related congenital muscular dystrophy.

Congenital muscular dystrophies are a group of progressive disorders with wide range of symptoms associated with diverse cellular mechanisms. Recently, biallelic variants in GGPS1 were linked to a distinct autosomal recessive form of muscular dystrophy associated with hearing loss and ovarian insufficiency. In this report, we present a case of a young patient with a homozygous variant in GGPS1. The patient presented with only proximal muscle weakness, and elevated liver transaminases with spared hearing function. The hepatic involvement in this patient caused by a novel deleterious variant in the gene extends the phenotypic and genotypic spectrum of GGPS1 related muscular dystrophy.

Global Transcriptional Profiling of Granulosa Cells from Polycystic Ovary Syndrome Patients: Comparative Analyses of Patients with or without History of Ovarian Hyperstimulation Syndrome Reveals Distinct Biomarkers and Pathways.

Ovarian hyperstimulation syndrome (OHSS) is often a complication of polycystic ovarian syndrome (PCOS), the most frequent disorder of the endocrine system, which affects women in their reproductive years. The etiology of OHSS is multifactorial, though the factors involved are not apparent. In an attempt to unveil the molecular basis of OHSS, we conducted transcriptome analysis of total RNA extracted from granulosa cells from PCOS patients with a history of OHSS (n = 6) and compared them to those with no history of OHSS (n = 18). We identified 59 significantly dysregulated genes (48 down-regulated, 11 up-regulated) in the PCOS with OHSS group compared to the PCOS without OHSS group (p-value < 0.01, fold change >1.5). Functional, pathway and network analyses revealed genes involved in cellular development, inflammatory and immune response, cellular growth and proliferation (including DCN, VIM, LIFR, GRN, IL33, INSR, KLF2, FOXO1, VEGF, RDX, PLCL1, PAPPA, and ZFP36), and significant alterations in the PPAR, IL6, IL10, JAK/STAT and NF-κB signaling pathways. Array findings were validated using quantitative RT-PCR. To the best of our knowledge, this is the largest cohort of Saudi PCOS cases (with or without OHSS) to date that was analyzed using a transcriptomic approach. Our data demonstrate alterations in various gene networks and pathways that may be involved in the pathophysiology of OHSS. Further studies are warranted to confirm the findings.

A Novel Homozygous Founder Variant of RTN4IP1 in Two Consanguineous Saudi Families.

The genetic architecture of mitochondrial disease continues to expand and currently exceeds more than 350 disease-causing genes. Bi-allelic variants in RTN4IP1, also known as Optic Atrophy-10 (OPA10), lead to early-onset recessive optic neuropathy, atrophy, and encephalopathy in the afflicted patients. The gene is known to encode a mitochondrial ubiquinol oxidoreductase that interacts with reticulon 4 and is thought to be a mitochondrial antioxidant NADPH oxidoreductase. Here, we describe two unrelated consanguineous families from the northern region of Saudi Arabia harboring a missense variant (RTN4IP1:NM_032730.5; c.475G

Clinical, radiological, and genetic characterization of SLC13A5 variants in Saudi families: Genotype phenotype correlation and brief review of the literature.

Background: SLC13A5 (solute carrier family 13, member 5) encodes sodium/citrate cotransporter, which mainly localizes in cellular plasma membranes in the frontal cortex, retina, and liver. Pathogenic variants of the gene cause an autosomal recessive syndrome known as "developmental and epileptic encephalopathy 25 with amelogenesis imperfecta." Results: Here, we have investigated six patients from three different consanguineous Saudi families. The affected individuals presented with neonatal seizures, developmental delay, and significant defects in tooth development. Some patients showed other clinical features such as muscle weakness, motor difficulties, intellectual disability, microcephaly, and speech problems in addition to additional abnormalities revealed by electroencephalography (EEGs) and magnetic resonance imaging (MRI). One of the MRI findings was related to cortical thickening in the frontal lobe. To diagnose and study the genetic defects of the patients, whole exome sequencing (WES) coupled with confirmatory Sanger sequencing was utilized. Iterative filtering identified two variants of SLC13A5, one of which is novel, in the families. Families 1 and 2 had the same insertion (a previously reported mutation), leading to a frameshift and premature stop codon. The third family had a novel splice site variant. Confirmatory Sanger sequencing corroborated WES results and indicated full segregation of the variants in the corresponding families. The patients' conditions were poorly controlled by multiple antiepileptics as they needed constant care. Conclusion: Considering that recessive mutations are common in the Arab population, SLC13A5 screening should be prioritized in future patients harboring similar symptoms including defects in molar development.

Detailed genetic and clinical analysis of a novel de novo variant in HPRT1: Case report of a female patient from Saudi Arabia with Lesch-Nyhan syndrome.

Background: Hypoxanthine-guanine phosphoribosyltransferase (HPRT1) deficiency is an inborn error of purine metabolism responsible for Lesch-Nyhan syndrome (LNS). The disease is inherited in an X-linked recessive manner and predominantly affects male individuals. Female individuals can carry a mutation as heterozygotes, but typically, they are asymptomatic because of the random inactivation of the affected allele. Nevertheless, although rare, heterozygote female individuals may manifest LNS with full characteristics. Herein, we describe a female patient from Saudi Arabia with LNS. Results: The patient (a 4-year-old girl) presented with typical characteristics of the disease, which include global developmental delay, self-mutilation, hyperuricemia, hypotonia, speech delay, spasticity, and seizures. Her general biochemical laboratory results were normal except for high levels of uric acid. The abdominal MRI\MRS, mostly unremarkable, showed bilateral echogenic foci within the renal collecting system. Genetic testing (whole-exome sequencing, iterative variant filtering, segregation analysis, and Sanger sequencing) pointed a novel de novo frameshift variant in HPRT1. X-inactivation assay using HpaII showed the presence of a 100% skewed X chromosome carrying the affected allele. RT-PCR of the cDNA indicated complete loss of the expression of the normal allele. Conclusion: Our study presents a female patient who has a severe case of LNSand found to be the 15th female patient with the disease in the world. The study emphasizethe need for a streamlined protocol that will help an early and accurate diagnosis of female LNS patients to avoid unnecessary interventions that lead to costly patient care.

SLC25A42-associated mitochondrial encephalomyopathy: Report of additional founder cases and functional characterization of a novel deletion.

SLC25A42 is the main transporter of coenzyme A (CoA) into mitochondria. To date, 15 individuals have been reported to have one of two bi-allelic homozygous missense variants in the SLC25A42 as the cause of mitochondrial encephalomyopathy, of which 14 of them were of Saudi origin and share the same founder variant, c.871A > G:p.Asn291Asp. The other subject was of German origin with a variant at canonical splice site, c.380 + 2 T > A. Here, we describe the clinical manifestations and the disease course in additional six Saudi patients from four unrelated consanguineous families. While five patients have the Saudi founder p.Asn291Asp variant, one subject has a novel deletion. Functional analyses on fibroblasts obtained from this patient revealed that the deletion causes significant decrease in mitochondrial oxygen consumption and ATP production compared to healthy individuals. Moreover, extracellular acidification rate revealed significantly reduced glycolysis, glycolytic capacity, and glycolytic reserve as compared to control individuals. There were no changes in the mitochondrial DNA (mtDNA) content of patient fibroblasts. Immunoblotting experiments revealed significantly diminished protein expression due to the deletion. In conclusion, we report additional patients with SLC25A42-associated mitochondrial encephalomyopathy. Our study expands the molecular spectrum of this condition and provides further evidence of mitochondrial dysfunction as a central cause of pathology. We therefore propose that this disorder should be included in the differential diagnosis of any patient with an unexplained motor and speech delay, recurrent encephalopathy with metabolic acidosis, intermittent or persistent dystonia, lactic acidosis, basal ganglia lesions and, especially, of Arab ethnicity. Finally, deep brain stimulation should be considered in the management of patients with life altering dystonia.

Bi-allelic variants in HOPS complex subunit VPS41 cause cerebellar ataxia and abnormal membrane trafficking.

Membrane trafficking is a complex, essential process in eukaryotic cells responsible for protein transport and processing. Deficiencies in vacuolar protein sorting (VPS) proteins, key regulators of trafficking, cause abnormal intracellular segregation of macromolecules and organelles and are linked to human disease. VPS proteins function as part of complexes such as the homotypic fusion and vacuole protein sorting (HOPS) tethering complex, composed of VPS11, VPS16, VPS18, VPS33A, VPS39 and VPS41. The HOPS-specific subunit VPS41 has been reported to promote viability of dopaminergic neurons in Parkinson's disease but to date has not been linked to human disease. Here, we describe five unrelated families with nine affected individuals, all carrying homozygous variants in VPS41 that we show impact protein function. All affected individuals presented with a progressive neurodevelopmental disorder consisting of cognitive impairment, cerebellar atrophy/hypoplasia, motor dysfunction with ataxia and dystonia, and nystagmus. Zebrafish disease modelling supports the involvement of VPS41 dysfunction in the disorder, indicating lysosomal dysregulation throughout the brain and providing support for cerebellar and microglial abnormalities when vps41 was mutated. This provides the first example of human disease linked to the HOPS-specific subunit VPS41 and suggests the importance of HOPS complex activity for cerebellar function.

A Novel GEMIN4 Variant in a Consanguineous Family Leads to Neurodevelopmental Impairment with Severe Microcephaly, Spastic Quadriplegia, Epilepsy, and Cataracts.

Pathogenic variants in GEMIN4 contribute to a hereditary disorder characterized by neurodevelopmental features, microcephaly, cataracts, and renal abnormalities (known as NEDMCR). To date, only two homoallelic variations have been linked to the disease. Moreover, clinical features associated with the variants have not been fully elucidated yet. Here, we identified a novel variant in GEMIN4 (NM_015721:exon2:c.440A>G:p.His147Arg) in two siblings from a consanguineous Saudi family by using whole exome sequencing followed by Sanger sequence verification. We comprehensively investigated the patients' clinical features, including brain imaging and electroencephalogram findings, and compared their phenotypic characteristics with those of previously reported cases. In silico prediction and structural modeling support that the p.His147Arg variant is pathogenic.

Pyrostigmine therapy in a patient with VAMP1-related congenital myasthenic syndrome.

Congenital myasthenic syndrome comprises several genetic disorders that impair neuromuscular junction transmission. Causative mutations occur in at least 30 genes, approximately 6-8% of which are presynaptic. One such gene, VAMP1, encodes vesicle-associated membrane protein-1, which is crucial in the formation and fusion of synaptic vesicles with the presynaptic membrane at the neuromuscular junction. VAMP1 mutations are associated with two main phenotypes: a) autosomal recessive congenital myasthenic syndrome and b) autosomal dominant spastic ataxia 1. We report a girl from a consanguineous Saudi family presenting with hypotonia, developmental delay, feeding difficulties and floppiness since birth. Comprehensive genetic testing revealed a homozygous splicing mutation in VAMP1. RT-PCR confirmed the presence of an aberrant transcript causing skipping of exon 2 in the gene.

Ancient founder mutation in RUBCN: a second unrelated family confirms Salih ataxia (SCAR15).

BACKGROUND: Homozygous frameshift mutation in RUBCN (KIAA0226), known to result in endolysosomal machinery defects, has previously been reported in a single Saudi family with autosomal recessive spinocerebellar ataxia (Salih ataxia, SCAR15, OMIM # 615705). The present report describes the clinical, neurophysiologic, neuroimaging, and genetic findings in a second unrelated Saudi family with two affected children harboring identical homozygous frameshift mutation in the gene. It also explores and documents an ancient founder cerebellar ataxia mutation in the Arabian Peninsula. CASE PRESENTATION: The present family has two affected males (aged 6.5 and 17 years) with unsteady gait apparent since learning to walk at 2.5 and 3 years, respectively. The younger patient showed gait ataxia and normal reflexes. The older patient had saccadic eye movement, dysarthria, mild upper and lower limb and gait ataxia (on tandem walking), and enhanced reflexes in the lower limbs. Cognitive abilities were mildly impaired in the younger sibling (IQ 67) and borderline in the older patient (IQ 72). Nerve conduction studies were normal in both patients. MRI was normal at 2.5 years in the younger sibling. Brain MRI showed normal cerebellar volume and folia in the older sibling at the age of 6 years, and revealed minimal superior vermian atrophy at the age of 16 years. Autozygome and exome analysis showed both affected have previously reported homoallelic mutation in RUBCN (NM_014687:exon18:c.2624delC:p.A875fs), whereas the parents are carriers. Autozygosity mapping focused on smallest haplotype on chromosome 3 and mutation age analysis revealed the mutation occurred approximately 1550 years ago spanning about 62 generations. CONCLUSIONS: Our findings validate the slowly progressive phenotype of Salih ataxia (SCAR15, OMIM # 615705) by an additional family. Haplotype sharing attests to a common founder, an ancient RUBCN mutation in the Arab population.

Identification of novel genomic imbalances in Saudi patients with congenital heart disease.

BACKGROUND: Quick genetic diagnosis of a patient with congenital heart disease (CHD) is quite important for proper health care and management. Copy number variations (CNV), chromosomal imbalances and rearrangements have been frequently associated with CHD. Previously, due to limitations of microscope based standard karyotyping techniques copious CNVs and submicroscopic imbalances could not be detected in numerous CHD patients. The aim of our study is to identify cytogenetic abnormalities among the selected CHD cases (n = 17) of the cohort using high density oligo arrays. RESULTS: Our screening study indicated that six patients (~35%) have various cytogenetic abnormalities. Among the patients, only patient 2 had a duplication whereas the rest carried various deletions. The patients 1, 4 and 6 have only single large deletions throughout their genome; a 3.2 Mb deletion on chromosome 7, a 3.35 Mb deletion on chromosome 3, and a 2.78 Mb a deletion on chromosome 2, respectively. Patients 3 and 5 have two deletions on different chromosomes. Patient 3 has deletions on chromosome 2 (2q24.1; 249 kb) and 16 (16q22.2; 1.8 Mb). Patient 4 has a 3.35 Mb an interstitial deletion on chromosome 3 (3q13.2q13.31).Based on our search on the latest available literature, our study is the first inclusive array CGH evaluation on Saudi cohort of CHD patients. CONCLUSIONS: This study emphasizes the importance of the arrays in genetic diagnosis of CHD. Based on our results the high resolution arrays should be utilized as first-tier diagnostic tool in clinical care as suggested before by others. Moreover, previously evaluated negative CHD cases (based on standard karyotyping methods) should be re-examined by microarray based cytogenetic methods.

Mutations in NALCN cause an autosomal-recessive syndrome with severe hypotonia, speech impairment, and cognitive delay.

Sodium leak channel, nonselective (NALCN) is a voltage-independent and cation-nonselective channel that is mainly responsible for the leaky sodium transport across neuronal membranes and controls neuronal excitability. Although NALCN variants have been conflictingly reported to be in linkage disequilibrium with schizophrenia and bipolar disorder, to our knowledge, no mutations have been reported to date for any inherited disorders. Using linkage, SNP-based homozygosity mapping, targeted sequencing, and confirmatory exome sequencing, we identified two mutations, one missense and one nonsense, in NALCN in two unrelated families. The mutations cause an autosomal-recessive syndrome characterized by subtle facial dysmorphism, variable degrees of hypotonia, speech impairment, chronic constipation, and intellectual disability. Furthermore, one of the families pursued preimplantation genetic diagnosis on the basis of the results from this study, and the mother recently delivered healthy twins, a boy and a girl, with no symptoms of hypotonia, which was present in all the affected children at birth. Hence, the two families we describe here represent instances of loss of function in human NALCN.

A novel mutation in a large family causes a unique phenotype of Mucolipidosis IV.

Mucolipidosis type IV is a rare autosomal recessive lysosomal storage disorder reported among Ashkenazi Jews and to a lesser extent in other ethnic groups. Several mutations have been reported in MCOLN1 which is the only known gene associated with the disorder. Here we report the first Saudi patient with Mucolipidosis type IV from a consanguineous family with two branches having a total of five patients carrying a novel transition mutation, c.1307A>G (p.Y436C) in exon 11. The clinical course of the patient was nonspecific and a lysosomal storage disorder was not highly suspected due to lack of coarse facial features, organomegaly and skeletal findings of dysostosis multiplex. The detailed bioinformatics analysis on the deleterious effects of the mutation is discussed. Emphasis is made on the importance of brain magnetic resonance imaging (MRI) findings and serum gastrin level as key clues to the diagnosis of this often subtle neurodevelopmental disorder.

Age-specific gene expression signatures for breast tumors and cross-species conserved potential cancer progression markers in young women.

Breast cancer in young women is more aggressive with a poorer prognosis and overall survival compared to older women diagnosed with the disease. Despite recent research, the underlying biology and molecular alterations that drive the aggressive nature of breast tumors associated with breast cancer in young women have yet to be elucidated. In this study, we performed transcriptomic profile and network analyses of breast tumors arising in Middle Eastern women to identify age-specific gene signatures. Moreover, we studied molecular alterations associated with cancer progression in young women using cross-species comparative genomics approach coupled with copy number alterations (CNA) associated with breast cancers from independent studies. We identified 63 genes specific to tumors in young women that showed alterations distinct from two age cohorts of older women. The network analyses revealed potential critical regulatory roles for Myc, PI3K/Akt, NF-κB, and IL-1 in disease characteristics of breast tumors arising in young women. Cross-species comparative genomics analysis of progression from pre-invasive ductal carcinoma in situ (DCIS) to invasive ductal carcinoma (IDC) revealed 16 genes with concomitant genomic alterations, CCNB2, UBE2C, TOP2A, CEP55, TPX2, BIRC5, KIAA0101, SHCBP1, UBE2T, PTTG1, NUSAP1, DEPDC1, HELLS, CCNB1, KIF4A, and RRM2, that may be involved in tumorigenesis and in the processes of invasion and progression of disease. Array findings were validated using qRT-PCR, immunohistochemistry, and extensive in silico analyses of independently performed microarray datasets. To our knowledge, this study provides the first comprehensive genomic analysis of breast cancer in Middle Eastern women in age-specific cohorts and potential markers for cancer progression in young women. Our data demonstrate that cancer appearing in young women contain distinct biological characteristics and deregulated signaling pathways. Moreover, our integrative genomic and cross-species analysis may provide robust biomarkers for the detection of disease progression in young women, and lead to more effective treatment strategies.

Clinical and biochemical features associated with BCS1L mutation.

Our study describes a novel phenotype in a series of nine Saudi patients with lactic acidosis, from four consanguineous families three of which are related. Detailed genetic studies including linkage, homozygosity mapping and targeted sequencing identified a causative mutation in the BCS1L gene. All affected members of the families have an identical mutation in this gene, mutations of which are recognized causes of Björnstad syndrome, GRACILE syndrome and a syndrome of neonatal tubulopathy, encephalopathy, and liver failure (MIM 606104) leading to isolated mitochondrial respiratory chain complex III deficiency. Here we report the appearance of a novel behavioral (five patients) and psychiatric (two patients) phenotype associated with a p.Gly129Arg BCS1L mutation, differing from the phenotype in a previously reported singleton patient with this mutation. The psychiatric symptoms emanated after childhood, initially as hypomania later evolving into intermittent psychosis. Neuroradiological findings included subtle white matter abnormalities, whilst muscle histopathology and respiratory chain studies confirmed respiratory chain dysfunction. The variable neuro-psychiatric manifestations and cortical visual dysfunction are most unusual and not reported associated with other BCS1L mutations. This report emphasizes the clinical heterogeneity associated with the mutation in BCS1L gene, even within the same family and we recommend that defects in this gene should be considered in the differential diagnosis of lactic acidosis with variable involvement of different organs.

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.

Novel V97G ASAH1 mutation found in Farber disease patients: unique appearance of the disease with an intermediate severity, and marked early involvement of central and peripheral nervous system.

Farber disease is a rare inherited lysosomal storage disorder caused by ceramidase deficiency that leads to accumulation of ceramide in various tissues. Mutations within ASAH1 encoding for acid ceramidase are responsible for the disease. Here we report two siblings with Farber disease who carry a novel V97G with the parents and a sister being asymptomatic carriers. The mutation site was found to be highly conserved among different species using ClustalW2 alignment. Functional prediction tools indicated the mutation to be pathogenic. Electron microscopy based ultrastructural studies using skin biopsy showed inclusion of enlarged lysosomes and presence of the zebra bodies. The T1 weighted magnetic resonance images of the brain indicated diffuse loss of the deep white matter volume predominantly along the occipital horns of the lateral ventricle with subsequent facet dilatation of the supratentorial and infratentorial ventricular system. This is the first report of a detailed clinical and molecular analysis of cases with Farber disease from Saudi Arabia.

Genomic and transcriptomic analyses distinguish classic Rett and Rett-like syndrome and reveals shared altered pathways.

Rett syndrome (RTT) is an X-linked neurodevelopmental disorder characterized by derangements in nervous system especially in cognition and behavior. The present study aims to understand the molecular underpinnings of two subtypes of RTT, classic RTT and Rett-like, and to elucidate common pathways giving rise to common RTT phenotype using genomic and transcriptomic approaches. Mutation screening on selected nuclear genes revealed only MECP2 mutations in a subset of classic RTT patients. MLPA assays and mtDNA screenings were all negative. Genome-wide copy number analysis indicated a novel duplication on X chromosome. Transcriptional profiling revealed blood gene signatures that clearly distinguish classic RTT and RTT-like patients, as well as shared altered pathways in interleukin-4 and NF-κB signaling pathways in both subtypes of the syndrome. To our knowledge, this is the first report on investigating common regulatory mechanisms/signaling pathways that may be relevant to the pathobiology of the "common RTT" phenotype.

Array comparative genomic hybridization (aCGH) reveals the largest novel deletion in PCCA found in a Saudi family with propionic acidemia.

Propionic acidemia is a metabolic disorder (OMIM 606054) caused by deficiency of the propionyl-coenzyme A (CoA) carboxylase, which subsequently results in accumulation of propionic acid. Patients may initially present with poor feeding, vomiting, loss of appetite, hypotonia, and lethargy. Later, most children will show different degrees of motor, social and language delay even more serious medical problems, including heart abnormalities, seizures, coma, and possibly death. Two siblings affected with propionic acidemia were screened for putative mutations in PCCA and PCCB genes coding alpha and beta subunits of propionyl-coenzyme A (CoA) carboxylase, respectively. Both patients had a mild-severe form of propionic acidemia. The investigations using PCR, long-PCR, array comparative genomic hybridization (aCGH), and sequencing techniques showed a approximately 73kb deletion extending from intron 16 to intron 19 and an 18bp insertion at the distal end of the deletion in PCCA gene. The deletion so far is the largest gross change reported in the literature for the PCCA gene.