Expanding the allelic spectrum of ELOVL4-related autosomal recessive neuro-ichthyosis

BACKGROUND

Very long-chain fatty acids (VLCFAs) composed of more than 20 carbon atoms are essential in the biosynthesis of cell membranes in the brain, skin, and retina. VLCFAs are elongated beyond 28 carbon atoms by ELOVL4 enzyme. Variants in ELOVL4 are associated with three Mendelian disorders: autosomal dominant (AD) Stargardt-like macular dystrophy type 3, AD spinocerebellar ataxia, and autosomal recessive disorder congenital ichthyosis, spastic quadriplegia and impaired intellectual development (ISQMR). Only seven subjects from five unrelated families with ISQMR have been described, all of which have biallelic single-nucleotide variants.

METHODS

We performed clinical exome sequencing on probands from four unrelated families with neuro-ichthyosis.

RESULTS

We identified three novel homozygous ELOVL4 variants. Two of the families originated from the same Saudi tribe and had the exact homozygous exonic deletion in ELOVL4, while the third and fourth probands had two different novel homozygous missense variants. Seven out of the eight affected subjects had profound developmental delay, epilepsy, axial hypotonia, peripheral hypertonia, and ichthyosis. Delayed myelination and corpus callosum hypoplasia were seen in two of five subjects with brain magnetic rosonance imaging and cerebral atrophy in three.

CONCLUSION

Our study expands the allelic spectrum of ELOVL4-related ISQMR. The detection of the same exonic deletion in two unrelated Saudi family from same tribe suggests a tribal founder mutation.

Biotin-thiamine responsive basal ganglia disease: a retrospective review of the clinical, radiological and molecular findings of cases in Kuwait with novel variants

BACKGROUND

Biotin-thiamine-responsive basal ganglia disease (BTBGD) is a rare autosomal recessive neurometabolic disorder that is caused by biallelic pathogenic SLC19A3 variants and is characterized by subacute encephalopathy associated with confusion, convulsions, dysphagia, dysarthria, or other neurological manifestations.

METHODS

A retrospective review of the data registry in Kuwait Medical Genetics Center for all cases diagnosed clinically and radiographically and confirmed genetically with BTBGD.

RESULTS

Twenty one cases from 13 different families were diagnosed with BTBGD in Kuwait. Most cases (86%) presented with confusion, dystonia, convulsions, or dysarthria, while three individuals were diagnosed pre-symptomatically during familial targeted genetic screening. Symptoms resolved completely within 2-week of treatment in two-thirds of the symptomatic cases but progressed in six of them to a variety of severe symptoms including severe cogwheel rigidity, dystonia and quadriparesis due to delayed presentation and management. Neuroradiological findings of the symptomatic cases revealed bilateral central changes in the basal ganglia. Two novel homozygous missense SLC19A3 variants were detected in a Kuwaiti and a Jordanian individuals, in addition to the previously reported Saudi founder homozygous variant, c.1264A > G; p.(Thr422Ala) in the remaining cases. Age of diagnosis ranged from newborn to 32 years, with a median age of 2-3 years. All cases are still alive receiving high doses of biotin and thiamine.

CONCLUSION

This is the first study reporting the phenotypic and genotypic spectrum of 21 individuals with BTBGD in Kuwait and describing two novel SLC19A3 variants. BTBGD is a treatable neurometabolic disease that requires early recognition and treatment initiation. This study highlights the importance of performing targeted molecular testing of the founder variant in patients presenting with acute encephalopathy in the region.

SMPD4 regulates mitotic nuclear envelope dynamics and its loss causes microcephaly and diabetes

Biallelic loss of function (LoF) variants in SMPD4 cause a rare and severe neurodevelopmental disorder with progressive congenital microcephaly and early death. SMPD4 encodes a sphingomyelinase that hydrolyzes sphingomyelin into ceramide at neutral pH and can thereby affect membrane lipid homeostasis. SMPD4 localizes to the membranes of the endoplasmic reticulum and nuclear envelope (NE), and interacts with nuclear pore complexes (NPC). We refine the clinical phenotype of LoF SMPD4 variants by describing five individuals from three unrelated families with longitudinal data due to prolonged survival. All individuals surviving beyond infancy developed insulin-dependent diabetes, besides presenting with a severe neurodevelopmental disorder (NDD) and microcephaly, making diabetes one of the most frequent age-dependent non-cerebral abnormalities. We studied the function of SMPD4 at the cellular and organ levels. Knock-down of SMPD4 in human neural stem cells, causes reduced proliferation rates and prolonged mitosis. Moreover, SMPD4 depletion results in abnormal NE breakdown and reassembly during mitosis and decreased post-mitotic NPC insertion. Fibroblasts from affected individuals show deficient SMPD4-specific neutral sphingomyelinase activity, without changing (sub)cellular lipidome fractions, which suggests a local function of SMPD4 on the NE. In embryonic mouse brain, knockdown of Smpd4 impairs cortical progenitor proliferation and induces premature differentiation by altering the balance between neurogenic and proliferative progenitor cell divisions. We hypothesize that, in individuals with SMPD4-related disease, NE bending, which is needed to insert NPCs in the nuclear envelope, is impaired in the absence of SMPD4, and interferes with cerebral corticogenesis and survival of pancreatic beta cells.

Gene Therapy for Duchenne Muscular Dystrophy: Unlocking the Opportunities in Countries in the Middle East and Beyond

Background: Duchenne muscular dystrophy (DMD) is a severe neuromuscular disorder which leads to progressive muscle degeneration and weakness. Most patients die from cardiac or respiratory failure. Gene transfer therapy offers a promising approach to treating this disorder. Objective: Given the genetic disease burden, family size, and the high consanguinity rates in the Middle East, our objective is to address current practices and challenges of DMD patient care within two countries in this region, namely the United Arab Emirates and Kuwait, and to outline readiness for gene therapy. Methods: An expert panel meeting was held to discuss the DMD patient journey, disease awareness, current management of DMD, challenges faced and recommendations for improvement. Opportunities and challenges for gene therapy in both countries were also deliberated. A pre-meeting survey was conducted, and the results were used to guide the discussion during the meeting. Results: DMD awareness is poor resulting in a delay in referral and diagnosis of patients. Awareness and education initiatives, along with an interconnected referral system could improve early diagnosis. Genetic testing is available in both countries although coverage varies. Corticosteroid therapy is the standard of care however there is often a delay in treatment initiation. Patients with DMD should be diagnosed and managed by a multi-disciplinary team in centers of excellence for neuromuscular disorders. Key success factors to support the introduction of gene therapy include education and training, timely and accessible genetic testing and resolution of reimbursement and cost issues. Conclusion: There are many challenges facing the management of DMD patients in the United Arab Emirates and Kuwait and most likely other countries within the Middle East. Successful introduction of gene therapy to treat DMD will require careful planning, education, capacity building and prioritization of core initiatives.

Early Diagnosis of Classic Homocystinuria in Kuwait through Newborn Screening: A 6-Year Experience

Kuwait is a small Arabian Gulf country with a high rate of consanguinity and where a national newborn screening program was expanded in October 2014 to include a wide range of endocrine and metabolic disorders. A retrospective study conducted between January 2015 and December 2020 revealed a total of 304,086 newborns have been screened in Kuwait. Six newborns were diagnosed with classic homocystinuria with an incidence of 1:50,000, which is not as high as in Qatar but higher than the global incidence. Molecular testing for five of them has revealed three previously reported pathogenic variants in the CBS gene, c.969G>A, p.(Trp323Ter); c.982G>A, p.(Asp328Asn); and the Qatari founder variant c.1006C>T, p.(Arg336Cys). This is the first study to review the screening of newborns in Kuwait for classic homocystinuria, starting with the detection of elevated blood methionine and providing a follow-up strategy for positive results, including plasma total homocysteine and amino acid analyses. Further, we have demonstrated an increase in the specificity of the current newborn screening test for classic homocystinuria by including the methionine to phenylalanine ratio along with the elevated methionine blood levels in first-tier testing. Here, we provide evidence that the newborn screening in Kuwait has led to the early detection of classic homocystinuria cases and enabled the affected individuals to lead active and productive lives.

[When all roads lead to Africa…]

Congenital myopathies represent a quite heterogeneous group of neuromuscular disorders both at the clinical and genetic level. High-throughput sequencing (NGS), targeted or not, combined with muscle pathology, greatly facilitate their accurate characterization and occasionally lead to unexpected discoveries like in the case reported here in a Kuwaiti family facing a long diagnostic odyssey.

Recurrent homozygous damaging mutation in TMX2, encoding a protein disulfide isomerase, in four families with microlissencephaly

BACKGROUND

Protein disulfide isomerase (PDI) proteins are part of the thioredoxin protein superfamily. PDIs are involved in the formation and rearrangement of disulfide bonds between cysteine residues during protein folding in the endoplasmic reticulum and are implicated in stress response pathways.

METHODS

Eight children from four consanguineous families residing in distinct geographies within the Middle East and Central Asia were recruited for study. All probands showed structurally similar microcephaly with lissencephaly (microlissencephaly) brain malformations. DNA samples from each family underwent whole exome sequencing, assessment for repeat expansions and confirmatory segregation analysis.

RESULTS

An identical homozygous variant in TMX2 (c.500G>A), encoding thioredoxin-related transmembrane protein 2, segregated with disease in all four families. This variant changed the last coding base of exon 6, and impacted mRNA stability. All patients presented with microlissencephaly, global developmental delay, intellectual disability and epilepsy. While TMX2 is an activator of cellular C9ORF72 repeat expansion toxicity, patients showed no evidence of C9ORF72 repeat expansions.

CONCLUSION

The TMX2 c.500G>A allele associates with recessive microlissencephaly, and patients show no evidence of C9ORF72 expansions. TMX2 is the first PDI implicated in a recessive disease, suggesting a protein isomerisation defect in microlissencephaly.

Current management of Duchenne muscular dystrophy in the Middle East: expert report

Aim:

Duchenne muscular dystrophy (DMD) is a severe and rare X-linked neuromuscular childhood disorder that results in functional decline, loss of ambulation and early death due to cardiac or respiratory failure. The objective of this paper is to address different aspects of the current management of DMD in the Middle East, north Africa (MENA) region, and to gather experts’ recommendations on how to optimally diagnose and treat patients suffering from this disease.

Methods:

A group of experts (neuromuscular medicine, neuropediatricians and geneticists) convened to discuss the diagnosis and management of DMD in the MENA region. A list of practical statements was prepared by the chair of the meeting to guide the discussions around critical aspects relating to the current and future management of DMD.

Results & conclusion:

Ideally, DMD management should be a multidisciplinary approach. Nevertheless, few tertiary care hospitals in the region are currently able to provide the full spectrum of medical expertise and services needed by DMD patients. Clinical practice in the region remains heterogeneous. Specific guidelines for diagnosis and treatment are needed in the MENA region to improve outcomes. Disease awareness among the general public and the medical community is lacking. Now that mutation-specific therapies are being developed and more widely studied, general education programs regarding early signs and symptoms, a standardized referral and diagnosis pathway, patient registries and support groups will significantly improve the management of the disease.

STAC3 variants cause a congenital myopathy with distinctive dysmorphic features and malignant hyperthermia susceptibility

SH3 and cysteine-rich domain-containing protein 3 (STAC3) is an essential component of the skeletal muscle excitation-contraction coupling (ECC) machinery, though its role and function are not yet completely understood. Here, we report 18 patients carrying a homozygous p.(Trp284Ser) STAC3 variant in addition to a patient compound heterozygous for the p.(Trp284Ser) and a novel splice site change (c.997-1G > T). Clinical severity ranged from prenatal onset with severe features at birth, to a milder and slowly progressive congenital myopathy phenotype. A malignant hyperthermia (MH)-like reaction had occurred in several patients. The functional analysis demonstrated impaired ECC. In particular, KCl-induced membrane depolarization resulted in significantly reduced sarcoplasmic reticulum Ca²⁺ release. Co-immunoprecipitation of STAC3 with Ca_V 1.1 in patients and control muscle samples showed that the protein interaction between STAC3 and Ca_V 1.1 was not significantly affected by the STAC3 variants. This study demonstrates that STAC3 gene analysis should be included in the diagnostic work up of patients of any ethnicity presenting with congenital myopathy, in particular if a history of MH-like episodes is reported. While the precise pathomechanism remains to be elucidated, our functional characterization of STAC3 variants revealed that defective ECC is not a result of Ca_V 1.1 sarcolemma mislocalization or impaired STAC3-Ca_V 1.1 interaction.

GNE myopathy in the bedouin population of Kuwait: Genetics, prevalence, and clinical description

INTRODUCTION

GNE myopathy is a rare recessive myopathy caused by mutations in the GNE gene. It is mainly a distal myopathy with relative sparing of the quadriceps muscle.

METHODS

Patients with distal myopathies from Kuwait were examined and tested for the Middle Eastern GNE gene founder mutation, p.M743T. Patients were further studied for disease-associated features.

RESULTS

GNE myopathy was confirmed in 14 of the 37 patients (37.8%) screened. All cases were caused by the p.M743T mutation. Age of onset and time from disease onset to loss of ambulation were variable. Both wasted and hypertrophied calf muscles were noted. Severely affected quadriceps were present in 1 patient, and ptosis, ophthalmoplegia, and tongue wasting in another.

DISCUSSION

The scope of the p.M743T mutation now includes the Arabian Peninsula. Variations in age of onset, disease progression, and distribution in patients harboring the same mutation suggest the role of other genetic- and environment-modifying factors. Muscle Nerve 58: 700-707, 2018.

Mutation spectrum analysis of Duchenne/Becker muscular dystrophy in 68 families in Kuwait: The era of personalized medicine

Duchenne and Becker muscular dystrophies (DMD/BMD) are X-linked recessive neuromuscular disorders characterized by progressive irreversible muscle weakness and atrophy that affect both skeletal and cardiac muscles. DMD/BMD is caused by mutations in the Dystrophin gene on the X chromosome, leading to the absence of the essential muscle protein Dystrophin in DMD. In BMD, Dystrophin is partially functioning with a shorter protein product. Recent advances in molecular therapies for DMD require precise genetic diagnoses because most therapeutic strategies are mutation-specific. Hence, early diagnosis is crucial to allow appropriate planning for patient care and treatment. In this study, data from DMD/BMD patients who attended the Kuwait Medical Genetic Center during the last 20 years was retrieved from a Kuwait neuromuscular registry and analyzed. We combined multiplex PCR and multiplex ligation-dependent probe amplification (MLPA) with Sanger sequencing to detect Dystrophin gene mutations. A total of 35 different large rearrangements, 2 deletion-insertions (Indels) and 4 substitution mutations were identified in the 68 unrelated families. The deletion and duplication rates were 66.2% and 4.4%, respectively. The analyzed data from our registry revealed that 11 (16%) of the DMD families will benefit from newly introduced therapies (Ataluren and exon 51 skipping). At the time of submitting this paper, two cases have already enrolled in Ataluren (Tranlsarna™) therapy, and one case has been enrolled in exon 51 skipping therapy.

Mutations in B4GALNT1 (GM2 synthase) underlie a new disorder of ganglioside biosynthesis

Glycosphingolipids are ubiquitous constituents of eukaryotic plasma membranes, and their sialylated derivatives, gangliosides, are the major class of glycoconjugates expressed by neurons. Deficiencies in their catabolic pathways give rise to a large and well-studied group of inherited disorders, the lysosomal storage diseases. Although many glycosphingolipid catabolic defects have been defined, only one proven inherited disease arising from a defect in ganglioside biosynthesis is known. This disease, because of defects in the first step of ganglioside biosynthesis (GM3 synthase), results in a severe epileptic disorder found at high frequency amongst the Old Order Amish. Here we investigated an unusual neurodegenerative phenotype, most commonly classified as a complex form of hereditary spastic paraplegia, present in families from Kuwait, Italy and the Old Order Amish. Our genetic studies identified mutations in B4GALNT1 (GM2 synthase), encoding the enzyme that catalyzes the second step in complex ganglioside biosynthesis, as the cause of this neurodegenerative phenotype. Biochemical profiling of glycosphingolipid biosynthesis confirmed a lack of GM2 in affected subjects in association with a predictable increase in levels of its precursor, GM3, a finding that will greatly facilitate diagnosis of this condition. With the description of two neurological human diseases involving defects in two sequentially acting enzymes in ganglioside biosynthesis, there is the real possibility that a previously unidentified family of ganglioside deficiency diseases exist. The study of patients and animal models of these disorders will pave the way for a greater understanding of the role gangliosides play in neuronal structure and function and provide insights into the development of effective treatment therapies.

Using whole-exome sequencing to identify inherited causes of autism

Despite significant heritability of autism spectrum disorders (ASDs), their extreme genetic heterogeneity has proven challenging for gene discovery. Studies of primarily simplex families have implicated de novo copy number changes and point mutations, but are not optimally designed to identify inherited risk alleles. We apply whole-exome sequencing (WES) to ASD families enriched for inherited causes due to consanguinity and find familial ASD associated with biallelic mutations in disease genes (AMT, PEX7, SYNE1, VPS13B, PAH, and POMGNT1). At least some of these genes show biallelic mutations in nonconsanguineous families as well. These mutations are often only partially disabling or present atypically, with patients lacking diagnostic features of the Mendelian disorders with which these genes are classically associated. Our study shows the utility of WES for identifying specific genetic conditions not clinically suspected and the importance of partial loss of gene function in ASDs.

Distinguishing 3 classes of corpus callosal abnormalities in consanguineous families

OBJECTIVE

We sought to create a classification system for pediatric corpus callosal abnormalities (CCA) based upon midline sagittal brain MRI. We used the term CCA for patients with structural variants of the corpus callosum, excluding patients with interhemispheric cyst variant or pure dysplasia without hypoplasia. Currently, no system exists for nonsyndromic forms of CCA, and attempts to create such a system have been hampered by highly variable morphology in patients with sporadic CCA. We reasoned that any useful strategy should classify affected family members within the same type, and that phenotypic variability should be minimized in patients with recessive disease.

METHODS

We focused recruitment toward multiplex consanguineous families, ascertained 30 patients from 19 consanguineous families, and analyzed clinical features together with brain imaging.

RESULTS

We identified 3 major CCA classes, including hypoplasia, hypoplasia with dysplasia, and complete agenesis. Affected individuals within a given multiplex family usually displayed the same variant of the class of abnormality and they always displayed the same class of abnormality within each family, or they displayed complete agenesis. The system was validated among a second cohort of 10 sporadic patients with CCA.

CONCLUSIONS

The data suggest that complete agenesis may be a common end-phenotype, and implicate multiple overlapping pathways in the etiology of CCA.

Expanding CEP290 mutational spectrum in ciliopathies

Ciliopathies are an expanding group of rare conditions characterized by multiorgan involvement, that are caused by mutations in genes encoding for proteins of the primary cilium or its apparatus. Among these genes, CEP290 bears an intriguing allelic spectrum, being commonly mutated in Joubert syndrome and related disorders (JSRD), Meckel syndrome (MKS), Senior-Loken syndrome and isolated Leber congenital amaurosis (LCA). Although these conditions are recessively inherited, in a subset of patients only one CEP290 mutation could be detected. To assess whether genomic rearrangements involving the CEP290 gene could represent a possible mutational mechanism in these cases, exon dosage analysis on genomic DNA was performed in two groups of CEP290 heterozygous patients, including five JSRD/MKS cases and four LCA, respectively. In one JSRD patient, we identified a large heterozygous deletion encompassing CEP290 C-terminus that resulted in marked reduction of mRNA expression. No copy number alterations were identified in the remaining probands. The present work expands the CEP290 genotypic spectrum to include multiexon deletions. Although this mechanism does not appear to be frequent, screening for genomic rearrangements should be considered in patients in whom a single CEP290 mutated allele was identified.

Sanjad-Sakati syndrome/Kenny-Caffey syndrome type 1: a study of 21 cases in Kuwait

We studied 21 patients with Sanjad-Sakati syndrome (SSS) from 16 families. Parental consanguinity was recorded in 2 families (12.5%). All patients had severe intrauterine growth retardation, short stature, small hands and feet, blue sclera, deep-set eyes, microcephaly, persistent hypocalcaemia and hypoparathyroidism. Medullary stenosis was detected in 2 patients. Cytogenetic and fluorescent in situ hybridization studies were normal. All affected persons had homozygous deletion of 12 bp (155-166del) in exon 3 of the TBCE gene. All of the parents were heterozygous carriers of this mutation. The high frequency of SSS and low frequency of consanguineous marriages in this study may reflect a high rate of heterozygous carriers.

Trisomy 18 in Kuwait

BACKGROUND

Trisomy 18 (Edwards' syndrome, T18) is the second most common trisomy in man. We describe 118 children with regular T18 who were ascertained clinically and cytogenetically in the Kuwait Medical Genetics Centre during 1980-1997.

METHODS

Ascertainment of T18 cases was performed shortly after birth. Chromosomal studies were carried out in addition to other relevant investigations. To investigate the factors associated with T18, a case-control study was carried out with 131 normal healthy newborns. Studied factors included maternal and paternal age, birth order, abortion, associated malformation, and survival. Multiple logistic regression analysis was used to adjust for confounding between variables.

RESULTS

There was a preponderance of females among T18 cases (female:male ratio 2.1:1). The majority of T18 cases (53%) died before the second week of life. The most common associated anomalies were: congenital heart (38.1%) and gastrointestinal (25.4%). Multiplicity of malformations was also observed. Significant seasonal variation in T18 cases was detected with a peak in spring. Of the 118 T18 cases, 59 were delivered during 1994-1997 (average overall T18 birth prevalence rate 8.95 per 10 000 live births [95% CI: 6.66-11.23]). Concerning maternal age, 30.5% of the T18 cases' mothers were > or =35 years compared to 10.7% in the control group. The difference was statistically significant, P = 0.002. Logistic regression analysis showed that maternal age >30 years was a significant risk factor for T18, after adjusting for confounding with paternal age. Paternal age and abortion were not found to be significant risk factors.

CONCLUSION

Trisomy 18 birth prevalence rate is high in Kuwait with advanced maternal age as a significant risk factor.

Clustering of trisomy 18 in Kuwait: Genetic predisposition or environmental?

BACKGROUND

This study describes 59 newborns with regular trisomy 18 (EdwardsA centAA syndrome, T18) who were ascertained clinically and cytogenetically at the Kuwait Medical Genetic Centre from 1994 to 1997, out of 118 T18 cases identified from 1980 to 1997.

MATERIALS AND METHODS

T18 cases were ascertained clinically and cytogenetically shortly after birth. In addition to assessing the T18 birth prevalence rate and confidence limits during the years 1994-1997, we investigated the possible etiological factors by a case-control study with normal healthy newborns. Studied factors included gender, parental age, birth order, abortion, clinical variables (presentation, amniotic fluid and mode of delivery), and survival.

RESULTS

The average T18 birth prevalence rate during the period was 8.95 per 10,000 live births (95% confidence limits 6.66-11.23). The T18 cases were mostly females, with a male:female ratio of 1:2.1, and the majority (53%) died before the second week of life. Maternal age above 30 years was found to be a significant factor for T18.

CONCLUSION

This high T18 birth prevalence rate suggests clustering of T18 in the highly inbred population of Kuwait. Such clustering may indicate a possible environmental, and to a lesser extent, genetic predisposition to aneuploidy nondisjunction.

Screening 25 dystrophin gene exons for deletions in Arab children with Duchenne muscular dystrophy

Forty-two Arab children with Duchenne muscular dystrophy (DMD) were studied for intragenic deletions in 25 exons of the dystrophin gene using three different multiplex PCR sets each amplifying a total of 9, 9 and 6 different exons, respectively. Exon 22 was amplified individually. Deletions were found in 78, 76 and 12% of DMD patients with each of the three sets, respectively. With all the three sets, the detection rate increased to 86% (36 of 42 patients). Fifty percent of the deleted exons were located in the distal hot spot, 8% in the proximal hot spot while 42% were scattered over both. This study, the first in an Arab population and only the second to use three PCR multiplex sets, documents one of the highest deletion detection rates in DMD.

Unusual traits associated with Robinow syndrome

We report on some members of two unrelated families showing the characteristic features of Robinow syndrome. In a consanguineous Kuwaiti family, the index case with Robinow syndrome showed some unusual features including severe IUGR, laxity of ligaments, hyperextensible joints, redundant skin folds, severe normocytic anaemia, repeated infection, increased percentage of total T cells and CD4 positive population, reduced percentage of CD8 positive cells, and EMG abnormality. In a Pakistani family with a high degree of multigenerational consanguinity, a single case with the Robinow phenotype also had congenital heart disease, mainly involving the right side of the heart, with pulmonary stenosis, tricuspid atresia, ASD, VSD, double outlet right ventricle, and right atrial isomerism. This report suggests that the disease profile of Robinow syndrome may be extended to accommodate the unusual traits mentioned above. The association of the Robinow phenotype with congenital heart disease in case 2 of this report is consistent with the previously reported finding that congenital heart disease, particularly involving the right side of the heart, may be a prominent component of Robinow syndrome in a subset of patients.

Deletion analysis of the SMN and NAIP genes in Kuwaiti patients with spinal muscular atrophy

Two genes are known to be involved in spinal muscular atrophy (SMA), namely, SMN (survival motor neuron) and NAIP (neuronal apoptosis inhibitory protein). Deletion analysis of these genes has been reported for many ethnic groups. We have extended this analysis to include 15 Arabic patients (11 unrelated cases of type I, which represent practically all of the patients diagnosed within the last 2 years in Kuwait, and 4 type-II cases from a single kinship). Also, 41 healthy relatives (parents and sibs) and 44 control individuals of Arabic origin were analyzed. The homozygous deletions of exons 7 and 8 of the SMN gene were found in all SMA patients studied. Exon 5 of NAIP was homozygously absent in all type-I patients, but was retained in type-II cases. Among members of SMA families, one mother was found to be homozygously deleted for NAIP. All of the control individuals had both normal SMN and NAIP. Our results are in agreement with the general consensus that the incidence of NAIP deletion is higher in the more severe SMA cases. Furthermore, they suggest that SMA type-I chromosomes, with the dual deletion of the SMN and NAIP genes, are more common in Arabs than in patients of other ethnic origin.

Disease profile of 400 institutionalized mentally retarded patients in Kuwait

In this preliminary report we summarize the results of a 4-year multidisciplinary systematic, etiological clinicogenetic survey of 400 institutionalized mentally retarded patients in Kuwait. All had an intelligence quotient below 50. A constitutional disorder, as the direct cause of the mental retardation, was found in 203 patients (50.75%)): a chromosomal abnormality in 37 (9.25%), Mendelian disorders in 137 (34.25%), MCA/MR in 22 (5.55%) and CNS malformations in 7 cases (1.75%). In 157 patients (39.35%) a pre-, peri or postnatal cause was ascertained. No etiological diagnosis was detected in 40 patients (10%). A detailed analysis of the "disease profile" is given and compared with the results of previous diagnostic genetic surveys among different institutionalized mentally retarded populations in Western and developing countries.

The newly recognised limb/pelvis-hypoplasia/aplasia syndrome: report of a Bedouin patient and review

A Bedouin infant born to consanguineous parents and grandparents is reported. She had Müllerian aplasia and the phenotypic features of the limb/pelvis-hypoplasia/aplasia syndrome (MIM 276820). Phenotypic variability of this newly recognised syndrome is briefly discussed.