Neuronal Apoptosis Inhibitory Protein Gene Research Articles

NAIP Gene Deletion and SMN2 Copy Number as Molecular Tools in Predicting the Severity of Spinal Muscular Atrophy.

Spinal muscular atrophy (SMA) is one of the most prevalent autosomal recessive illnesses with type I being the most severe type. Genomic alterations including survival motor neuron (SMN) copy number as well as deletions in SMN and Neuronal Apoptosis Inhibitory Protein (NAIP) are greatly implicated in the emergence of SMA. However, the association of such alterations with the severity of the disease is yet to be investigated. This study was directed to elucidate the molecular assessment of NAIP and SMN genomic alterations as a useful tool in predicting the severity of SMA among patients. This study included 65 SMA pediatric patients (30 type I and 35 type II) and 65 healthy controls. RFLP-PCR was employed to determine the genetic polymorphisms of the SMN1, SMN2, and NAIP genes. In addition, qRT-PCR was used to identify the expression of the SMN1 and SMN2 genes, and serum levels of creatine kinase were measured using a colorimetric method. DNA sequencing was performed on some samples to detect any single nucleotide polymorphisms in SMN1, SMN2, and NAIP genes. All SMA patients had a homozygous deficiency of SMN1 exon 7. The homozygous deficiency of SMN1 exons 7 and 8, with the deletion of NAIP exon 5 was found among the majority of Type I patients. In contrast, patients with the less severe condition (type II) had SMN1 exons 7 and 8 deleted but did not have any deletions in NAIP, additionally; 65.7% of patients had multiple copies of SMN2. Analysis of NAIP deletion alongside assessing SMN2 copy number might enhance the effectiveness of the diagnosis that can predict severity among Spinal Muscular Atrophy patients.

Deletions of SMNI gene exon 7 and NAIP gene exon 5 in spinal muscular atrophy patients in selected population.

Spinal muscular atrophy (SMA) is common among various populations because the genetic makeup is monogamous due to consanguineous marriages. Two genes, i.e., survival motor neuron (SMN1) and neuronal apoptosis inhibitory protein (NAIP) are mapped to the SMA vicinity of chromosome 5q13. The main objective of the study was to develop a solitary advanced genetic tool for the diagnosis of SMA by using SMN1 gene exon 7 and NAIP gene exon 5. This study involved SMA patients (n=84) belonging to different clinical features and socio-economic status. The identity of the intact NAIP gene is primarily based on the amplification of exon 5 only in those SMA patients that have a deletion of SMN1 gene exon 7. Healthy controls (n=84) were also included in this study. The mutational analysis was observed through the Sanger sequencing method, where chromatograms were observed by using Chromas version 2.6.0. This study showed a higher prevalence of SMA in females than in males. NAIP gene is considered a phenotype modifier as most SMA patients (94.90%) have SMN1 exon 7 deletion along with a deletion in exon 5 of the NAIP gene. Single nucleotide conversion C-T in exon 7 of SMN1 gene leads to its complete deletion. Mutated proteins encoded by SMN1 and NAIP genes also result in degeneration and muscle weakness in SMA patients. These SMA-associated gene deletions can be used as a molecular evaluation tool for pre- and postnatal diagnosis of SMA. This will be valuable when there is a need for precise and consistent results with a strong focus on quantification.

The First Report of Iranian Registry of Patients with Spinal Muscular Atrophy.

Insufficient amounts of survival motor neuron protein is leading to one of the most disabling neuromuscular diseases, spinal muscular atrophy (SMA). Before the current study, the detailed characteristics of Iranian patients with SMA had not been determined. To describe the key demographic, clinical, and genetic characteristics of patients with SMA registered in the Iranian Registry of SMA (IRSMA). IRSMA has been established since 2018, and the demographic, clinical, and genetic characteristics of patients with SMA were recorded according to the methods of treat neuromuscular disease (TREAT-NMD) project. By October 1, 2022, 781 patients with 5q SMA were registered. Of them, 164 patients died, the majority of them had SMA type 1 and died during the first 20 months of life. The median survival of patients with type 1 SMA was 23 months. The consanguinity rate in 617 alive patients was 52.4%, while merely 24.8% of them had a positive family history. The most common type of SMA in live patients was type 3. Morbidities were defined as having scoliosis (44.1%), wheelchair dependency (36.8%), tube feeding (8.1%), and requiring mechanical ventilation (9.9%). Most of the registered patients had a homozygous deletion of SMN1, while the frequency of patients with higher copy numbers of SMN2, was less in more severe types of the disease. Earlier onset of the disease was significantly seen in patients with lower copy numbers of SMN2. The neuronal apoptosis inhibitory protein (NAIP) gene deletion was associated with a higher incidence of more severe types of SMA, higher dependency on ventilators, tube feeding, and earlier onset of the disease. The IRSMA is the first established Iranian nationwide registry of patients with SMA. Using this registry, decision-makers, researchers, and practitioners can precisely understand the epidemiology, characteristics, and genetics of patients with SMA in Iran.

The analysis of the association between the copy numbers of survival motor neuron gene 2 and neuronal apoptosis inhibitory protein genes and the clinical phenotypes in 40 patients with spinal muscular atrophy: Observational study.

In this article, the correlation between the copy number of survival motor neuron 2 (SMN2) gene, neuronal apoptosis inhibitory protein (NAIP), and the phenotype of spinal muscular atrophy patients were analyzed.Forty patients with spinal muscular atrophy (SMA) were included in the study at the Department of Medical Genetics of the First People's Hospital and the Department of Neurology of the Second People's Hospital in Yunnan Province from January 2012 to September 2018. Multiplex ligation-dependent probe amplification assay was performed to determine the copy numbers of SMN2 and NAIP genes. Statistical analysis was performed to determine the correlation between copy numbers of the SMN2 and NAIP genes and the clinical phenotypes of SMA.Our results show that among the 40 SMA patients, there were 13 type I cases, 16 type II cases and 11 type III cases. A total of 37 patients possessed a homozygous deletion of SMN1 exons 7 and 8, while the other 3 SMA patients possessed a single copy of SMN1 exon 8. There was no correlation between SMA subtypes and the deletion types of SMN1 exon 7 and 8 (P = .611). The percentage of 2, 3, and 4 copies of SMN2 exon 7 was 25.0%, 62.5%, and 12.5%, respectively. The percentage of 0, 1, and 2 copies of NAIP exon 5 was 10%, 57.5%, and 32.5%, respectively. The distributions of SMN2 and NAIP copy numbers among various SMA types were significantly different (all P < .05). Five combined SMN1-SMN2-NAIP genotypes were detected, of which 0-3-1 genotype had the highest proportion than the others, accounting for 42.5%. The copy number of SMN2 and NAIP gene had synergistic effect on SMA phenotype. The combined SMN1-SMN2-NAIP genotypes with fewer copies were associated with earlier onset age, higher mortality, and smaller average age at death in SMA patients.Therefore, we conclude that the copy number variance of SMN2 and NAIP is correlated with the SMA phenotype. Analysis of the copy number structure of the SMN1-SMN2-NAIP gene is helpful for SMA typing, disease prognosis prediction, and genetic counseling.

Genotype-Phenotype Correlation of SMN1 and NAIP Deletions in Korean Patients with Spinal Muscular Atrophy.

Background and PurposeSpinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disease characterized by progressive muscle weakness and atrophy. Most SMA patients have a homozygous deletion in survival of motor neuron 1 (SMN1) gene, and neuronal apoptosis inhibitory protein (NAIP) gene is considered a phenotype modifier. We investigated the genotype-phenotype correlation of SMN1 and NAIP deletions in Korean SMA patients.MethodsThirty-three patients (12 males and 21 females) treated at the Asan Medical Center between 1999 and 2013 were analyzed retrospectively. The polymerase chain reaction (PCR), restriction-fragment-length polymorphism analysis, and multiplex PCR were used to detect deletions in SMN1 (exons 7 and 8) and NAIP (exons 4 and 5). We reviewed clinical presentations and outcomes and categorized the patients into three clinical types. NAIP deletion-driven differences between the two genotypes were analyzed.ResultsDeletion analysis identified homozygous deletions of SMN1 exons 7 and 8 in 30 patients (90.9%). Among these, compared with patients without an NAIP deletion, those with an NAIP deletion showed a significantly lower age at symptom onset (1.9±1.7 months vs. 18.4±20.4 months, mean±SD; p=0.007), more frequent type 1 phenotype (6/6 vs. 8/24, p=0.005), and worse outcomes, with early death or a requirement for ventilator support (4/4 vs. 2/12, p=0.008).ConclusionsHomozygous deletion in SMN1 and a concurrent NAIP deletion were associated with an early onset, severe hypotonia, and worse outcome in SMA patients. Deletion analysis of NAIP and SMN1 can help to accurately predict prognostic outcomes in SMA.

Spinal muscular atrophy type III: Molecular genetic characterization of Turkish patients

Spinal Muscular Atrophy (SMA) is a neurodegenerative disease with autosomal recessive inheritance. Homozygous loss of exon 7 of the Survival of motor neuron 1 (SMN1) gene is the main cause of SMA. Although progressive muscle weakness and atrophy are common symptoms, disease severity varies from severe to mild. Type III is one of the milder and less frequent forms of SMA. In this study, we report molecular genetic characteristics of 24 Turkish type III SMA patients. Homozygous loss of SMN1 exon 7 and 8 was analysed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and multiplex ligation dependent probe amplification (MLPA). SMN2, homologue of SMN1, and Neuronal apoptosis inhibitory protein (NAIP) genes were also evaluated considering their influence on disease severity. We determined that male patients who were born in consanguineous families were predominant in our cohort and these patients mostly carry the homozygous loss of SMN1 exon 7 and 8 and four copies of SMN2 gene without NAIP deletions.

Correlation between deletion patterns of SMN1 and NAIP genes and clinical subtypes of spinal muscular atrophy in Iranian Azeri Turk ethnic patients

The childhood spinal muscular atrophy (SMA) is classified into three groups based on the age of onset and clinical course. The aim of this study was to define the correlation between genotype and phenotype in Iranian patients with SMA. Molecular analysis was carried out on two candidate genes of survival motor neuron one (SMN1), and neuronal apoptosis in- hibitory protein (NAIP) in 189 patients with SMA (130 patients with SMA type I, 32 patients with type II and 27 patients with type III) and the phenotypic features of SMA were compared with the deletion pattern of these genes. Polymerase chain reaction along with restriction fragment length polymorphism analysis were used to detect the deletion of exons 7 and 8 of SMN1 gene, as well as multiplex polymerase chain reaction for exon 5 of NAIP gene. Deletion in exon 7 was detected in 167 patients (88.4%); deletion in exon 8 was detected in 162 patients (85.7%) and deletion in exon 5 of NIAP gene was detected in 95 patients (50.3%). Deletion of exons 7 and/or 8 of SMN1 were detected in 90%, 84.4%, and 88.9% in patients with types I, II and III SMA, re- spectively. The prevalence rates of exon 5 deletion in NAIP gene was 66.9%, 12.5%, and 14.8% in types I, II and III SMA patients, respectively (P < 0.001). Combined homozygous deletion in both SMN1 and NAIP genes was found in 65.4% SMA type I, 12.5% SMA type II and 14.8% SMA type III (P < 0.001).There was a significant correlation between combined deletion of both SMN1 and NAIP genes and clinical subtypes of SMA patients.

Association of Copy Numbers of Survival Motor Neuron Gene 2 and Neuronal Apoptosis Inhibitory Protein Gene With the Natural History in a Chinese Spinal Muscular Atrophy Cohort

We evaluated survival motor neuron 2 (SMN2) and neuronal apoptosis inhibitory protein (NAIP) gene copy distribution and the association of copy number with survival in 232 Chinese spinal muscular atrophy (SMA) patients. The SMN2 and NAIP copy numbers correlated positively with the median onset age (r = 0.72 and 0.377). The risk of death for patients with fewer copies of SMN2 or NAIP was much higher than for those with more copies (P < .01). The survival probabilities at 5 years were 5.1%, 90.7%, and 100% for 2, 3, and 4 SMN2 copies and 27.9%, 66.7%, and 87.2% for 0, 1, and 2 NAIP copies, respectively. Our results indicated that combined SMN1-SMN2-NAIP genotypes with fewer copies were associated with earlier onset age and poorer survival probability. Better survival status for Chinese type I SMA might due to a higher proportion of 3 SMN2 and a lower rate of zero NAIP.

A randomized controlled trial of gonadotropin-releasing hormone agonist versus gonadotropin-releasing hormone antagonist in Iranian infertile couples: oocyte gene expression.

BackgroundThe main objective of the present work was to compare the effects of the gonadotropin-releasing hormone agonist (GnRH-a) and GnRH antagonist (GnRH-ant) on the gene expression profiles of oocytes obtained from Iranian infertile couples undergoing in vitro fertilization (IVF).MethodsFifty infertile couples who underwent IVF between June 2012 and November 2013 at the Infertility Center of Tehran Women General Hospital, Tehran University of Medical Sciences, were included in this study. We included women that had undergone IVF treatment because of male factor, tubal factor, or unexplained infertility. The women randomly underwent controlled ovarian stimulation (COS) with either the GnRH-a (n = 26) or the GnRH-ant (n = 24). We obtained 50 germinal vesicle (GV) oocytes donated by women in each group. After the sampling, pool of 50 GV oocytes for each group was separately analyzed by quantitative polymerase chain reaction (qPCR).ResultThe expression levels of Adenosine triphosphatase 6 (ATPase 6), Bone morphogenetic protein 15 (BMP15), and Neuronal apoptosis inhibitory protein (NAIP) genes were significantly upregulated in the GnRH-ant group compared to the GnRH-a group, with the fold change of 3.990 (SD ± 1.325), 6.274 (SD ± 1.542), and 2.156 (SD ± 1.443), respectively, (P < 0.001). Growth differentiation factor 9 (GDF9) mRNA did not have any expression in the GnRH-a group; however, GDF9 mRNA was expressed in the GnRH-ant group. Finally, it was found that the genes involved in the DNA repairing and cell cycle checkpoint did not have any expression in either group.ConclusionThe present study showed, for the first time, the expression levels of genes involved in the cytoplasmic maturity (BMP15, GDF9), adenosine triphosphate production (ATPase 6), and antiapoptotic process (NAIP), in human GV oocytes were significantly higher in the GnRH-anta group than in the GnRH-a group in COS. Higher expression level of these genes when GnRH-ant protocol is applied, this protocol seems to be a more appropriate choice for women with poly cystic ovarian syndrome, because it can probably improve the expression of the aforementioned genes.Trial registrationCurrent Controlled Trials: IRCT 2014031112307 N3.

Genotype-phenotype correlation of survival motor neuron and neuronal apoptosis inhibitory protein genes in spinal muscular atrophy patients from Iran.

Background:Proximal spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disease characterized by symmetrical proximal muscle weakness and atrophy. According to the severity of the disease and the age of onset, SMA can be divided into three groups. The survival motor neuron (SMN) gene that is located on 5q13 is identified as the disease determining gene. Another gene in this region is neuronal apoptosis inhibitory protein (NAIP), and its functional role in the pathogenesis of SMA has not been fully elucidated. Here, we investigated the correlation between deletions in SMN and NAIP genes with clinical features of SMA patients.Materials and Methods:In the current study, 71 unrelated Iranian patients were investigated for the detection of deletions in SMN1 and NAIP genes. Polymerase chain reaction (PCR) was used to detect the deletions of exon 4 and 5 of the NAIP gene. Deletions in exon 7 and 8 of SMN1 gene were detected by RFLP-PCR with DraI and DdeI, respectively.Results:Our results showed that 51 patients have homozygous deletions in SMN1 and/or NAIP genes. Among these 51 patients, deletion in NAIP gene were found in 35 patients (65.7% of type I, 22.5% type II and 11.42% type III).Conclusion:Defect in SMN1 gene plays a major role in manifesting of the disease and NAIP (4 and 5) gene acts as a modifying factor in severity of symptoms. Correlation between NAIP gene defect and severity of the disease is confirmed. However, the exact role of NAIP gene in SMA has yet to be fully clarified.

Interaction with the Yes-associated protein (YAP) allows TEAD1 to positively regulate NAIP expression

Although the expression of the neuronal apoptosis inhibitory protein (NAIP) gene is considered involved in apoptosis suppression as well as in inflammatory response, the molecular basis of the NAIP gene expression is poorly understood. Here we show that the TEA domain protein 1 (TEAD1) is able to positively activate the transcription of NAIP. We further demonstrate that this regulation is mediated by the presence of the endogenous Yes associated protein (YAP) cofactor, and requires the interaction with YAP. We finally identified an intronic region of the NAIP gene responding to TEAD1/YAP activity, suggesting that regulation of NAIP by TEAD1/YAP is at the transcriptional level.

Clinical and Genetic Study of Algerian Patients with Spinal Muscular Atrophy.

Spinal muscular atrophy (SMA) is the second most common lethal autosomal recessive disorder. It is divided into the acute Werdnig-Hoffmann disease (type I), the intermediate form (type II), the Kugelberg-Welander disease (type III), and the adult form (type IV). The gene involved in all four forms of SMA, the so-called survival motor neuron (SMN) gene, is duplicated, with a telomeric (tel SMN or SMN1) and a centromeric copy (cent SMN or SMN2). SMN1 is homozygously deleted in over 95% of SMA patients. Another candidate gene in SMA is the neuronal apoptosis inhibitory protein (NAIP) gene; it shows homozygous deletions in 45–67% of type I and 20–42% of type II/type III patients. Here we studied the SMN and NAIP genes in 92 Algerian SMA patients (20 type I, 16 type II, 53 type III, and 3 type IV) from 57 unrelated families, using a semiquantitative PCR approach. Homozygous deletions of SMN1 exons 7 and/or 8 were found in 75% of the families. Deletions of exon 4 and/or 5 of the NAIP gene were found in around 25%. Conversely, the quantitative analysis of SMN2 copies showed a significant correlation between SMN2 copy number and the type of SMA.

Molecular prenatal diagnosis of autosomal recessive childhood spinal muscular atrophies (SMAs)

Autosomal recessive childhood spinal muscular atrophy (SMAs) is the second most common neuromuscular disorder and a common cause of infant disability and mortality. SMA patients are classified into three clinical types based on age of onset, and severity of symptoms. About 94% of patients have homozygous deletion of exon 7 in survival motor neuron (SMN1) gene. The neuronal apoptosis inhibitory protein (NAIP) gene was found to be more frequently deleted in the severest form of the disease. This study aimed to comment on the implementation of genetic counseling and prenatal diagnosis of SMAs for 85 fetuses from 75 Egyptian couples at risk of having an affected child. The homozygous deletion of exon 7 in SMN1 gene and the deletion of exon 5 of the NAIP gene were detected using PCR-REFLP and multiplex PCR methods respectively. Eighteen fetuses showed homozygous deletion of exon 7 in SMN1 gene and deletion of exon 5 in NAIP gene. In conclusion prenatal diagnosis is an important tool for accurate diagnosis and genetic counseling that help decision making in high risk families.

Studies on the prenatal diagnosis of spinal muscular atrophy by multiplex ligation-dependent probe amplification

Objective To investigate the value of multiplex ligation⁃dependent probe amplification (MLPA) method in the prenatal diagnosis of spinal muscular atrophy (SMA). Methods Six SMA pedigrees, which included 7 patients, 12 parents and 6 fetuses, were admitted in our hospital. MLPA was used to detect the survival motor neuron (SMN) and other modifier genes, according to steps of hybridization, ligation, PCR reaction, fragment separation by capillary electrophoresis and peak pattern evaluation. Synchronously, the deletion of SMN1 gene was detected by polymerase chain reaction⁃restriction fragment length polymorphism (PCR⁃RFLP). The DNA samples of fetuses were collected by centrifuging the amniotic fluid as well as derived from amniotic cell culture. Results According to MLPA, 7 patients and 1 fetus were detected to carry homozygous deletion of survival motor neuron 1 (SMN1) gene, which was also detected by PCR⁃PFLP. In addition, 11 parents and 5 fetuses carried one copy of SMN1 gene, while 1 parent who was also a carrier of SMA carried two copies of SMN1 gene. Furthermore, after being analyzed by MLPA, 10 cases carried one copy of SMN2 gene, while 15 cases had two copies of SMN2 gene. After detecting the neuronal apoptosis inhibitory protein (NAIP) gene, 3 cases had the deletion of NAIP gene while others showed normal. Conclusion MLPA can detect the deletion and quantify the copy numbers of SMN and other modifier genes, improving the efficiency and stability of genetic diagnosis. It is adequate for detecting patients and carriers of SMA, as well as providing reliable evidence for genetic counseling. DOI：10.3969/j.issn.1672⁃6731.2012.03.012

Spinal Müsküler Atrofi ve Moleküler Genetiği

Spinal muscular atrophy (SMA) is one of the most common autosomal recessive diseases, affecting aproximately 1 in 6,000 - 10,000 live births, and with a carrier frequency of aproximately 1 in 40- 60. The childhood SMAs can be classified clinically into three groups. Type I (Werdnig-Hoffmann) is the most severe form, with onset at ‹ 6 months of age and with death typically at ‹2 years of age. Type II SMA patients display an intermediate severity, with onset at ‹18 months of age and with an inability to walk. Type III (Kugelberg –Walender) individuals are able to walk independently and have a relatively mild phenotype, with onset at ›18 months of age. The gene involved in type I–III SMA has been mapped to 5q12-q13 by linkage analysis, and refined to a region of about 500 kb. The region contains a large inverted duplication consisting of at least four genes, which are present in a telomeric (t) and a centromeric (c) copy: survival motor neuron gene (SMN1 or SMNt and SMN2 or SMNc); neuronal apoptosis inhibitory protein gene (NAIP); basal transcription factor subunit p44 (BTFp44t and BTFp44c); and a novel protein with unknown function H4F5. Although homozygous deletions encompassing all these genes are found in SMA patients, it is now well established that mutations or deletions of SMN1 (MIM#600354) cause the disease. SMN2 (MIM# 601627) gene, however, does not prevent the disease but attenuates disease severity. Therefore, upregulating functional SMN protein level via inducing gene expression and/or restoring splicing is an important therapeutic approach such as use of histone deacetylase (HDAC) inhibitors.

Point mutation analysis of SMN1 gene in patients with spinal muscular atrophy

To identify the point mutations in survival motor neuron gene 1 SMN1 gene and confirm the existence of compound heterozygous mutations in Chinese patients with spinal muscular atrophy (SMA). Three unrelated patients were diagnosed and clinically typed according to the criteria of proximal SMA established by the International SMA Consortium. Multiplex ligation-dependent probe amplification (MLPA) analysis was carried out to measure the copy numbers of SMN1, SMN2 and neuronal apoptosis inhibitory protein gene (NAIP)in the patients. The point mutation analysis of SMN1 gene was performed by reversed transcript-polymerase chain reaction (RT-PCR) and cloning sequencing. The MLPA assay and point mutation analysis were also performed in the family members to confirm the transmission of the mutations. Two point mutations were identified in the present study, i.e., the p.Leu228X in one patient and p.Arg288Met in two patients. The mutation p.Arg288Met was first reported in Chinese and p.Leu228X was first reported in Mainland Chinese. The case carrying p.Leu228X mutation was diagnosed as SMA I with 2 copies of SMN2, and the cases with p.Arg288Met were diagnosed as SMA I and SMA II , respectively, with 3 copies of SMN2 gene. The mutations p.Leu228X and p.Arg288Met caused severe clinical phenotypes, SMA I or SMA II. This study suggested that the compound heterozygous mutations of SMN1 existed in Chinese SMA patients, which was rarely reported previously in Chinese. It was necessary to detect the point mutation in SMN1 for genetic diagnosis of those patients with heterozygous deletion of SMN1, which would be beneficial to prenatal diagnosis and genetic counseling in these families.

Lower Incidence of Deletions in the Survival of Motor Neuron Gene and the Neuronal Apoptosis Inhibitory Protein Gene in Children with Spinal Muscular Atrophy from Serbia

Spinal muscular atrophy (SMA) is the second most frequent autosomal recessive disease characterized by degeneration of the anterior horn cells of the spinal cord, leading to muscular atrophy. SMA is classified into three types according to disease severity and age-onset: severe (type I), intermediate (type II) and mild (type III). Deletions in the survival motor neuron (SMN) gene, located in the chromosome region 5q11.2- 5q13.3, are major determinants of SMA phenotype. Extended deletions that include the neuronal apoptosis inhibitory protein (NAIP) gene may correlate with the severtity of SMA. SMN gene is present in two highly homologous copies, SMN1 and SMN2, but only deletions of the SMN1 gene (exons 7 and 8 or exon 7) are responsible for clinical manifestations of SMA. Here, we present the deletion profiling of SMN1 and NAIP genes in 89 children with SMA from Serbia: 52 patients with type I, 26 with type II, and 11 with type III. The homozygous deletion of the SMN1 gene was confirmed in 72 of 89 (81%) patients, being the most frequent in SMA type I (48/52): 68 patients (94.4%) with deletion of exons 7 and 8 and 4 patients (5.6%) with deletion of exon 7. The extended deletion including the NAIP gene was detected in 18 of 89 (20.2%) patients, mostly affected with type I. This study has revealed the lower incidence of deletions in the SMN1 and NAIP genes in families with SMA in Serbia and will provide important information for genetic counselling in these families.

VERY SEVERE SPINAL MUSCULAR ATROPHY (TYPE 0): A REPORT OF THREE CASES

Objective three patients with very severe Spinal Muscular Atrophy (SMA) presented with reduced fetal movement in utero, profound hypotonia, severe weakness and respiratory insufficiency at birth. In all infants, electrodiagnostic studies were compatible with a neurogenic pattern. In genetic studies, all cases had homozygous deletions of exons 7 and 8 of Survival Motor Neuron (SMN) and exon 5 of Neuronal Apoptosis Inhibitory Protein (NAIP) gene. SMA should be considered in the differential diagnosis of reduced fetal movement and respiratory insufficiency at birth.

A Novel Protein Isoform of the Multicopy Human NAIP Gene Derives from Intragenic Alu SINE Promoters

The human neuronal apoptosis inhibitory protein (NAIP) gene is no longer principally considered a member of the Inhibitor of Apoptosis Protein (IAP) family, as its domain structure and functions in innate immunity also warrant inclusion in the Nod-Like Receptor (NLR) superfamily. NAIP is located in a region of copy number variation, with one full length and four partly deleted copies in the reference human genome. We demonstrate that several of the NAIP paralogues are expressed, and that novel transcripts arise from both internal and upstream transcription start sites. Remarkably, two internal start sites initiate within Alu short interspersed element (SINE) retrotransposons, and a third novel transcription start site exists within the final intron of the GUSBP1 gene, upstream of only two NAIP copies. One Alu functions alone as a promoter in transient assays, while the other likely combines with upstream L1 sequences to form a composite promoter. The novel transcripts encode shortened open reading frames and we show that corresponding proteins are translated in a number of cell lines and primary tissues, in some cases above the level of full length NAIP. Interestingly, some NAIP isoforms lack their caspase-sequestering motifs, suggesting that they have novel functions. Moreover, given that human and mouse NAIP have previously been shown to employ endogenous retroviral long terminal repeats as promoters, exaptation of Alu repeats as additional promoters provides a fascinating illustration of regulatory innovations adopted by a single gene.

Molecular analysis of the SMN and NAIP genes in Iranian spinal muscular atrophy patients

Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disorder characterized by degeneration of spinal cord anterior horn cells, leading to muscular atrophy. SMA is clinically classified into three subgroups based on the age of onset and severity. The majority of patients with SMA have homozygous deletions of exons 7 and 8 of the survival motor neuron (SMN) gene. The purpose of the present study was to determine the frequency of SMN and neuronal apoptosis inhibitory protein (NAIP) gene deletions in Iranian SMA patients. Experience in prenatal diagnosis of SMA in this population is also reported. To study the frequency of deletions of SMN and NAIP genes in an Iranian sample group, 75 unrelated SMA patients (54 type I, eight type II and 13 type III) were analyzed according to the methods described by van der Steege et al and Roy et al. Homozygous deletion of SMN1 exons 7 and/or 8 were identified in 68 out of 75 patients (90%). Deletion of exon 5 of the NAIP gene was found in 40/54 of type I, 2/8 of type II and 1/13 of type III patients. Deletion of the SMN1 gene is a major cause of SMA in Iran, and NAIP gene deletions were common in the present patients with type I SMA. Also, the incidence of NAIP deletion is higher in more severe SMA.