Plasma-separation in myasthenia gravis: A new method of rapid plasma exchange

Summary A patient with myasthenic crisis was successfully treated with a new method of plasma exchange using a hollow-fiber filter connected to a standard dialysis pump. The filter allows PE to be performed at more clinical centers and probably at lower costs than current methods applying blood cell separators.Supported by a grant from the Deutsche Forschungsgemeinschaft Bonn-Bad Godesberg (To 61/3)     

Diagnostic and clinical classification of autoimmune myasthenia gravis

Myasthenia gravis is characterized by muscle weakness and abnormal fatigability. It is an autoimmune disease caused by the presence of antibodies against components of the muscle membrane localized at the neuromuscular junction. In most cases, the autoantibodies are against the acetylcholine receptor (AChR). Recently, other targets have been described such as the MuSK protein (muscle-specific kinase) or the LRP4 (lipoprotein related protein 4). Myasthenia gravis can be classified according to the profile of the autoantibodies, the location of the affected muscles (ocular versus generalized), the age of onset of symptoms and thymic abnormalities.The disease generally begins with ocular symptoms (ptosis and/or diplopia) and extends to other muscles in 80% of cases. Other features that characterize MG include the following: variability, effort induced worsening, successive periods of exacerbation during the course of the disease, severity dependent on respiratory and swallowing impairment (if rapid worsening occurs, a myasthenic crisis is suspected), and an association with thymoma in 20% of patients and with other autoimmune diseases such as hyperthyroidism and Hashimoto's disease. The diagnosis is based on the clinical features, the benefit of the cholinesterase inhibitors, the detection of specific autoantibodies (anti-AChR, anti-MuSK or anti-LRP4), and significant decrement evidenced by electrophysiological tests.In this review, we briefly describe the history and epidemiology of the disease and the diagnostic and clinical classification. The neonatal form of myasthenia is explained, and finally we discuss the main difficulties of diagnosis.     

A comprehensive analysis of the epidemiology and clinical characteristics of anti-LRP4 in myasthenia gravis

Double-seronegative myasthenia gravis (dSN-MG, without detectable AChR and MuSK antibodies) presents a serious gap in MG diagnosis and understanding. Recently, autoantibodies against the low-density lipoprotein receptor-related protein 4 (LRP4) have been identified in several dSN-MG sera, but with dramatic frequency variation (∼2–50%). We have developed a cell based assay (CBA) based on human LRP4 expressing HEK293 cells, for the reliable and efficient detection of LRP4 antibodies. We have screened about 800 MG patient sera from 10 countries for LRP4 antibodies. The overall frequency of LRP4-MG in the dSN-MG group (635 patients) was 18.7% but with variations among different populations (range 7–32.7%). Interestingly, we also identified double positive sera: 8/107 anti-AChR positive and 10/67 anti-MuSK positive sera also had detectable LRP4 antibodies, predominantly originating from only two of the participating groups. No LRP4 antibodies were identified in sera from 56 healthy controls tested, while 4/110 from patients with other neuroimmune diseases were positive. The clinical data, when available, for the LRP4-MG patients were then studied. At disease onset symptoms were mild (81% had MGFA grade I or II), with some identified thymic changes (32% hyperplasia, none with thymoma). On the other hand, double positive patients (AChR/LRP4-MG and MuSK/LRP4-MG) had more severe symptoms at onset compared with any single positive MG subgroup. Contrary to MuSK-MG, 27% of ocular dSN-MG patients were LRP4 antibody positive. Similarly, contrary to MuSK antibodies, which are predominantly of the IgG4 subtype, LRP4 antibodies were predominantly of the IgG1 and IgG2 subtypes. The prevalence was higher in women than in men (female/male ratio 2.5/1), with an average disease onset at ages 33.4 for females and 41.9 for males. Overall, the response of LRP4-MG patients to treatment was similar to published responses of AChR-MG rather than to MuSK-MG patients.     

Differences in processing of an autoantigen by DR4:Dw4.2 and DR4:Dw14.2 antigen-presenting cells

Variations in antigen processing can influence class II-restricted T cell responses. We now report a highly significant difference (p < 0.001) between the ability of antigen-presenting cells from three HLA-DR4:Dw14.2 (Arg⁷¹) and six DR4:Dw4.2 (Lys⁷¹) individals to present recombinant or native acetylcholine receptor antigens to a myasthenia gravis T cell clone. The difference was greatest with longer antigens, and not seen with short synthetic peptides, suggesting that it may result from a difference in antigen processing between the two alleles. The results were not related to the presence of myasthenia gravis or of steroid therapy. They could, however, be of relevance in rheumatoid arthritis where particularly severe disease associates with Dw4.2/Dw14.2 heterozygosity.     

HLA DR-DQ-encoded genetic determinants of childhood-onset type 1 diabetes in Finland: an analysis of 622 nuclear families

The diabetes predisposing effect of HLA genes is defined by a complex interaction of various haplotypes. We analyzed the disease association of HLA DRB1-DQA1-DQB1 genotypes in a large nuclear family cohort (n = 622) collected in Finland. Using the affected family based artificial control approach we aimed at characterizing all detectable disease-specific HLA haplotype and genotype effects. The DRB1*0401-DQB1*0302 haplotype was the most prevalent disease susceptibility haplotype in the Finnish population followed by (DR3)-DQA1*05-DQB1*02 and DRB1*0404-DQB1*0302. DRB1*0405-DQB1*0302 conferred the highest disease risk, although this haplotype was very rare. The DRB1*04-DQB1*0304 was also associated with increased disease risk, an effect detected for the first time in the Finnish population. The following haplotypes showed significant protection from the disease and are listed in decreasing order of the strength of their effect: (DR7)-DQA1*0201-DQB1*0303, (DR14)-DQB1*0503, (DR15)-DQB1*0602, DRB1*0403-DQB1*0302, (DR13)-DQB1*0603, (DR11/12/13)-DQA1*05-DQB1*0301, (DR1)-DQB1*0501. In addition to the DRB1*0401/0404-DQB1*0302/(DR3)-DQA1*05-DQB1*02 genotype and DRB1*04-DQB1*0302 homozygous genotypes, heterozygous combinations DRB1*0401-DQB1*0302/(DR13)-DQB1*0604, approximately /(DR8)-DQB1*04, approximately /(DR9)-DQA1*03-DQB1*0303, approximately /(DR1)-DQB1*0501 and approximately /(DR7)-DQA1*0201-DQB1*02 were also disease-associated. As a new finding in this population, the (DR3)-DQA1*05-DQB1*02 homozygous and (DR3)-DQA1*05-DQB1*02/(DR9)-DQA1*03-DQB1*0303 heterozygous genotypes conferred disease susceptibility. Similarly, the DRB1*0401-DQB1*0302/(DR13)-DQB1*0603 genotype was disease predisposing, implying that DQB*0603-mediated protection from diabetes is not always dominant. Comparison of our findings with published data from other populations indicates a significant disease-specific heterogeneity of the (DR8)-DQB1*04, (DR7)-DQA1*0201-DQB1*02 and (DR3)-DQA1*05-DQB1*02 haplotypes.     

In vitro anti-acetylcholine receptor antibody synthesis by myasthenia gravis patient lymphocytes: Correlations with thymic histology and thymic epithelial-cell interactions

In vitro anti-acetylcholine receptor antibody (anti-AChR Ab) production by peripheral blood lymphocytes (PBL) and thymic lymphocytes was investigated in 52 patients with myasthenia gravis (MG). There was a positive correlation betweenin vitro anti-AChR Ab synthesis andin vivo titers. A relationship between the rates of synthesis by PBL and histological abnormalities of the thymus was also observed. Patients with hyperplastic thymus tended to produce the largest amountsin vitro, while those with an involuted thymus produced little or none. Production in thymoma patients is likely to correlate with the histological nature of the thymus associated with the tumor.In vitro Ab synthesis was modulated by the depletion of a cell subset for half of the patients tested. Finally, anti-AChR Ab production by thymocytes but not by PBL is enhanced by the addition of autologous or allogeneic thymic epithelial cells, suggesting a possible role of thymic epithelial cells in the autosensitization against AChR occurring in the thymus.     

Myocyte production of nitric oxide in response to AChR-reactive antibodies in two inbred rat strains may influence disease outcome in experimental myasthenia gravis

In an attempt to identify mechanisms that explain the difference in susceptibility of two rat strains to the induction of experimental autoimmune myasthenia gravis (EAMG), acetylcholine receptor (AChR)-reactive antibodies were tested for their ability to up-regulate levels of inducible nitric oxide synthase (iNOS) in skeletal muscles of disease-sensitive Lewis rats and disease-resistant Wistar Furth (WF) rats. Initially, the WF muscle cell line, WE1, appeared to be more sensitive to antibody-stimulated iNOS induction and NO production than did the Lewis muscle cell line, LE1. Next, AChR-reactive antibody induced widespread iNOS production in skeletal muscles of WF rats, while iNOS production in muscles of Lewis rats was much less pronounced. Finally, inhibition of iNOS activity by administration of a specific iNOS inhibitor resulted in increased susceptibility to the induction of impaired muscle function in EAMG-resistant WF rats. It is speculated that nitric oxide production plays a protective immunomodulating role in WF rats.     

New HLA haplotype frequency reference standards: high-resolution and large sample typing of HLA DR-DQ haplotypes in a sample of European Americans

A collaborative study involving a large sample of European Americans was typed for the histocompatibility loci of the HLA DR-DQ region and subjected to intensive typing validation measures in order to accurately determine haplotype composition and frequency. The resulting tables have immediate application to HLA typing and allogeneic transplantation. The loci within the DR-DQ region are especially valuable for such an undertaking because of their tight linkage and high linkage disequilibrium. The 3798 haplotypes, derived from 1899 unrelated individuals, had a total of 75 distinct DRB1-DQA1-DQB1 haplotypes. The frequency distribution of the haplotypes was right skewed with haplotypes occurring at a frequency of less than 1% numbering 59 and yet constituting less than 12% of the total sample. Given DRB1 typing, it was possible to infer the exact DQA1 and DQB1 composition of a haplotype with high confidence (>90% likelihood) in 21 of the 35 high-resolution DRB1 alleles present in the sample. Of the DRB1 alleles without high reliability for DQ haplotype inference, only *0401, *0701 and *1302 were common, the remaining 11 DRB1 alleles constituting less than 5% of the total sample. This approach failed for the 13 serologically equivalent DR alleles in which only 33% of DQ haplotypes could be reliably inferred. The 36 DQA1-DQB1 haplotypes present in the total sample conformed to the known pattern of permissible heterodimers. Four DQA1-DQB1 haplotypes, all rare, are reported here for the first time. The haplotype frequency tables are suitable as a reference standard for HLA typing of the DR and DQ loci in European Americans.     

家族性重症肌无力与HLA-DQB1等位基因多态性的相关性

目的探讨中国北方地区家族性重症肌无力（myasthenia gravis，MG）与HLA-DQB1等位基因多态性的相互关系。方法应用聚合酶链反应．序列特异性引物方法对中国北方地区15例家族性MG、49例散发性MG和51名健康对照组的HLA-DQB1基因多态性进行分析。结果在家族性MG中DQB1＊0501等位基因频率明显高于散发MG（P〈0．05，OR：3．08）和对照（P=0．001，OR=4．439），尤其是眼型患者更加显著有统计学意义（P〈0．01，OR=7．67）。结论DQB1＊0501等位基因是家族性MG尤其是眼型患者的易感基因；遗传因素与重症肌无力发生密切相关。家族性MG有其独特的临床特点。     

免疫学因素对重症肌无力患者外周血单个核细胞糖皮质激素受体的影响

目的　探讨重症肌无力 (MG)患者外周血单个核细胞 (PBMC)糖皮质激素受体 (GR)数改变的可能机制。方法　 13例MG患者及 11例正常对照PBMC在体外与乙酰胆碱受体 (AChR)、IFN γ或AChR +IFN γAb孵育前后同时测定PBMCGR数及GRmRNA含量。3H 地塞米松 (3H Dex)放射配体法测定GR数 ,狭缝印迹杂交法测定GRmRNA量 ,以 β actincDNA为内对照。同时 ,ELISA法测定患者血浆中的IFN γ含量及AChRAb水平。结果　正常对照PBMC分别在AChR、IFN γ、AChR +IFN γAb中培养后其GR数虽有降低 ,但未达到统计学意义 (P >0 .0 5 )。MG患者PBMC的GR数在AChR及IFN γ中培养后明显降低 (与培养前相比 ,前者P <0 .0 5 ,后者P <0 .0 1) ,而在AChR +IFN γAb中培养后则无明显改变 (P >0 .0 5 )。正常对照PBMC分别在AChR、IFN γ、AChR +IFN γAb中培养后其GRmRNA无显著降低 (P >0 .0 5 )。MG患者PBMC的GRmRNA在AChR及IFN γ中培养后与培养前相比明显降低 (前者P <0 .0 5 ,后者P <0 .0 1) ,而在AChR +IFN γAb中培养后则无明显改变 (P >0 .0 5 )。MG患者的血浆中IFN γ及AChRAb水平均显著高于正常对照 (前者P <0 .0 1;后者P <0 .0 5 )。MG患者的IFN γ含量与AChRAb水平间具有良好的正相关关系 (r=0 .92 ,P <0 .0 1)。MG患者的PBMC在体     

A triple antibody assay for the quantitation of plasma IgG subclass antibodies to acetylcholine receptors in patients with myasthenia gravis

Monoclonal anti-human IgG subclass antibodies have been used in an immunoprecipitation assay for the determination of anti-acetylcholine receptor IgG subclasses in plasma from patients with myasthenia gravis. Solubilized acetylcholine receptors labelled with 125I-alpha-bungarotoxin were incubated with patient plasma. Monoclonal mouse antibodies to human IgG subclasses 1-4 were added to the incubation and finally precipitated with anti-mouse IgG antibody. A maximal IgG subclass precipitation of 62-76% was determined with 125I-labelled myeloma IgG subclasses 1-4 added to normal human plasma. The anti-IgG subclass antibodies were added in excess which ensured that the precipitation of IgG2, IgG3 or IgG4 were unchanged, and that of IgG1 was only reduced by 17%, when the plasma IgG concentration was increased by a factor of two. The anti-IgG subclass antibodies were highly specific for their complementary subclasses. Determination of the IgG subclass of the anti-acetylcholine receptor antibodies from 8 patients with myasthenia gravis showed that IgG1 and IgG3 antibodies are predominant. This may support the hypothesis that complement mediated lysis of the neuromuscular end-plate plays a pathogenetic role in myasthenia gravis.     

Altered expression of transcription factors IRF4 and IRF8 in peripheral blood B cells is associated with clinical severity and circulating plasma cells frequency in patients with myasthenia gravis

Previous studies have shown that interferon regulatory factor-4 (IRF4) and IRF8 play critical but distinct roles in the differentiation of B cells into plasma cells (PCs). In the present study, we aimed to measure the expression levels of IRF4 and IRF8 in B cells from patients with myasthenia gravis (MG) and to investigate whether the expression of IRF4 and IRF8 associates with pathogenesis of MG. A total of 35 anti-acetylcholine receptor (AChR) antibody (Ab)-positive patients with MG [20 generalized MG (GMG) and 15 ocular MG (OMG) and 25 healthy donors were recruited in this study. The quantitative myasthenia gravis score (QMGS) was used to evaluate the clinical severity. Real-time PCR and Western blot were used to measure the levels of IRF4 and IRF8 expressed in peripheral blood B cells. Peripheral blood CD138⁺ PCs were assayed by flow cytometry. Our data demonstrated that the mRNA/protein levels of IRF4 and IRF8 were significantly higher and lower, respectively, in patients with OMG/GMG groups compared with healthy controls. In addition, IRF4 expression was significantly higher and IRF8 expression was significantly lower in GMG group than in OMG group. Pearson’s correlation analysis revealed that IRF8 expression was negatively correlated with clinical severity, PCs frequency and anti-AChR Ab levels, while IRF4 expression and IRF4/IRF8 ratio was positively correlated with these parameters in two MG subgroups. Finally, glucocorticoid treatment can relieve the imbalance of IRF4/IRF8 in peripheral blood B cells, and this restoration is accompanied by reduced PCs frequency and clinical symptoms. These evidences suggest that IRF4 and IRF8 are important in the counter-balancing mechanisms controlling differentiation of PCs in MG. The disruption of the balanced IRF4/IFR8 ratio in B cells may play important roles in the pathogenesis of MG and offer a promising therapeutic target for the development of novel immunotherapy for MG patients.     

Abnormal T cell receptor V gene usage in myasthenia gravis: prevalence and characterization of expanded T cell populations

The usage of T cell receptor (TCR) Vα/Vβ chains on cells from 38 patients with myasthenia gravis (MG) was determined by flow cytometry. There was a decreased number of cells expressing Vβ2 in CD8⁺ and Vβ3 in CD4⁺ cells in patients compared with healthy individuals. Abnormal expansions of T cells using particular TCR Vα/Vβ gene products were found in 18/38 patients. A significantly higher usage of Vβ13 was observed but there was no restriction with regard to other TCR Vα/Vβ. Expanded cells belonging to both CD4⁺ and CD8⁺ were present in MG patients while restricted to the CD8⁺ population in healthy individuals. To elucidate the role of the expanded populations, we studied characteristics of the expanded and non-expanded T cells from MG patients who had persistent T cell expansions over more than 2 years. The cells were analysed with regard to phenotype, cytokine secretion, cytokine mRNA expression and reactivity with the autoantigen, the acetylcholine receptor. The characteristics of the expanded populations in MG clearly differed from those found in healthy individuals. More cells in the CD4⁺ expanded populations expressed HLA-DR and there was also a tendency for higher expression of CD25, CD28 and CD57. The number of cells spontaneously secreting cytokines was higher in the expanded populations. A dominant Th1-type cytokine secretion and mRNA expression was noted. Autoantigen-reactive CD4⁺ T cells were largely restricted to the expanded populations.     

Role of HLA class II genes in susceptibility and resistance to multiple sclerosis: studies using HLA transgenic mice

Multiple sclerosis (MS), an inflammatory and demyelinating autoimmune disease of CNS has both, a genetic and an environmental predisposition. Among all the genetic factors associated with MS susceptibility, HLA class II haplotypes such as DR2/DQ6, DR3/DQ2, and DR4/DQ8 show the strongest association. Although a direct role of HLA-DR alleles in MS have been confirmed, it has been difficult to understand the contribution of HLA-DQ alleles in disease pathogenesis, due to strong linkage disequilibrium. Population studies have indicated that DQ alleles may play a modulatory role in the progression of MS. To better understand the mechanism by which HLA-DR and -DQ genes contribute to susceptibility and resistance to MS, we utilized single and double transgenic mice expressing HLA class II gene(s) lacking endogenous mouse class II genes. HLA class II transgenic mice have helped us in identifying immunodominant epitopes of PLP in context of various HLA-DR and -DQ molecules. We have shown that HLA-DR3 transgenic mice were susceptible to PLP_91–110 induced experimental autoimmune encephalomyelitis (EAE), while DQ6 (DQB1*0601) and DQ8 (DQB1*0302) transgenic mice were resistant. Surprisingly DQ6/DR3 double transgenic mice were resistant while DQ8/DR3 mice showed higher disease incidence and severity than DR3 mice. The protective effect of DQ6 in DQ6/DR3 mice was mediated by IFNγ, while the disease exacerbating effect of DQ8 molecule was mediated by IL-17. Further, we have observed that myelin-specific antibodies play an important role in PLP_91–110 induced EAE in HLA-DR3DQ8 transgenic mice. Based on these observations, we hypothesize that epistatic interaction between HLA-DR and -DQ genes play an important role in predisposition to MS and our HLA transgenic mouse model provides a novel tool to study the effect of linkage disequilibrium in MS.     

A novel loss of function mutation in exon 10 of the FSH receptor gene causing hypergonadotrophic hypogonadism: clinical and molecular characteristics

BACKGROUND: Inactivating mutations of the FSH receptor (FSHR) are a rare cause of hypergonadotrophic hypogonadism in women. Only one patient with primary amenorrhoea due to an FSHR gene mutation has been reported outside of Finland, where the prevalence of Ala189Val mutations is particularly high. METHODS AND RESULTS: Here, we describe the clinical, molecular genetic and functional characteristics associated with a novel inactivating mutation in exon 10 of the FSHR gene identified in a patient who presented with primary amenorrhoea at 17 years of age. The C to G transversion found at nucleotide 1043 causes a Pro348Arg substitution in the extracellular region of the FSHR and results in a mutant FSHR that is completely inactive in functional studies and that does not bind FSH. The proband exhibits apparent homozygosity for this recessive mutation. Her father is heterozygous for the mutation while analysis of exon 10 of the FSHR gene from her mother revealed only wild-type sequence. Chromosome painting was used to exclude deletions or rearrangements of 2p, and microsatellite markers did not show paternal uniparental isodisomy for this region. These findings suggest that the proband is hemizygous, with an inherited or de-novo microdeletion, or alternatively a de-novo gene conversion, of the accompanying FSHR allele. CONCLUSIONS: This case confirms the importance of the FSHR in female pubertal development and reproduction, and supports a relationship between phenotype and function for FSHR mutations.     

Autoimmune associations and autoantibody screening show focused recognition in patient subgroups with generalized myasthenia gravis

Autoimmune associations in myasthenia gravis (MG)-patients and their relatives have not been re-assessed since their separation into early- or late-onset MG (EOMG, LOMG), or thymoma-associated MG.     

Thymoma-associated myasthenia gravis: On the search for a pathogen signature

Myasthenia gravis (MG) is an autoimmune disease mainly mediated by anti-acetylcholine receptor (AChR) antibodies. In the late onset, a thymoma, tumor of the thymus, is quite frequent. However, the events leading to thymoma and MG are not understood. As thymoma-associated MG (MG-T) patients also display anti-interferon type I (IFN-I) neutralizing antibodies, we investigated if MG-T could be associated with an anti-viral signature.RT-PCR analyses demonstrated huge increases of IFN-I subtypes, IFN-α2, -α8, -ω and -β, in thymoma-associated MG but not in thymomas without MG or in control thymuses. Next, we investigated if dsRNA signaling pathway involvement could be observed in MG-T, as recently observed in early-onset MG. We observed an abnormal regulation of dsRNA-sensing molecules with an increase of toll-like receptor 3 (TLR3), and a decrease of protein kinase R (PKR) and dsRNA helicases (RIG-I and MDA5) in thymoma from MG patients. We also detected a decreased expression of p53, the tumor suppressor that is known to be down-regulated by dsRNA. Altogether, these results strongly suggest that MG-T could be linked to a viral infection.As p16 (CDKN2A), a marker of HPV infections, was up-regulated in MG-T, we thus screened DNA from thymomas for human papillomavirus (HPV) by real-time PCR using HPV consensus SPF10 primers. RT-PCR results were negative for all samples tested. We confirmed the absence of HPV DNA detection by end point PCR using FAP primers to amplify a larger panel of HPV genotypes.Our data clearly demonstrate INF-I overexpression together with the activation of innate immunity pathways in thymoma-associated MG suggesting that MG might develop after a pathogen infection. We were not able to relate thymoma to HPV infections and the implication of other pathogens is discussed.     

HLA class II DQA and DQB epitopes: Recognition of the likely binding sites of HLA-DQ alloantibodies eluted from recombinant HLA-DQ single antigen cell lines

Donor-specific antibodies (DSA) in sera of sensitized transplant patients are often produced against the specific epitopes on mismatched HLA antigens. In this study, we selected sera from 30 kidney transplant patients with DSA and AMR to define DQ epitopes. Using adsorption and elution assays, we identified 18 antibody reaction patterns to define 6 new epitopes and to confirm 12 previously defined epitopes. In one patient case, one mismatched antigen produced 3 different antibodies and, in another, antibodies were produced against the alpha and beta chains of the same antigen. For some sera, a single epitope can explain reactions for 27 of the 29 DQ beads in the single antigen panel.     

PDE3A variant associated with hypertension and brachydactyly syndrome in a patient with ischemic stroke caused by spontaneous intracranial artery dissection: A review of the clinical and molecular genetic features

Hypertension and brachydactyly syndrome (HTNB; MIM 112410) is a rare, recently described, autosomal dominant syndromic disease characterized by the triad of brachydactyly type E (BDE), short stature, and hypertension. HTNB is caused by a heterozygous mutation in the PDE3A (MIM 123805) gene on chromosome 12p12; this gene encodes a member of the cGMP-inhibited cyclic nucleotide phosphodiesterase family. PED3A plays a role in many signal transduction pathways, including those involved in vascular smooth muscle proliferation and contraction, cardiac contractility, platelet aggregation, and hormone secretion. Here, we present a new case of HTNB in a 42-year-old patient who experienced recurrent ischemic strokes in various vascular territories; these strokes were caused by intracranial multiarterial dissection, and were experienced for 2 weeks. She was found to harbor a de novo heterozygous in-frame deletion, c.1333_1335del p.(Thr445del), in exon 4 of the PDE3A gene. Our finding is expected to contribute to the elucidation of the pathophysiology of stroke in HTNB patients. We further review all clinical and molecular genetic features of this rare disease described in the literature to date.