Grange syndrome: an identifiable cause of stroke in young adults

Be aware of childhood stroke: Proceedings from EPNS Webinar

Childhood arterial ischaemic stroke (AIS) is a significant health concern with increasing incidence. This review aims to provide an overview of the current understanding of childhood AIS. The incidence of childhood AIS is on the rise especially in developing countries, likely due to improved awareness and diagnostic capabilities. Aetiology of childhood AIS is multifactorial, with both modifiable risk factors and genetic predisposition playing important roles. Identifying and addressing these risk factors, such as infection, sickle cell disease, and congenital heart defects, is essential in prevention and management. Identifying underlying conditions through genetic testing is important for appropriate management and long-term prognosis. Clinically, distinguishing stroke from stroke mimics can be challenging. Awareness of important stroke mimics, including migraines, seizures, and metabolic disorders, is crucial to avoid misdiagnosis and ensure appropriate treatment. The diagnostic approach to childhood AIS involves a comprehensive "chain of care," including initial assessment, neuroimaging, and laboratory investigations. National guidelines play a pivotal role in standardizing and streamlining the diagnostic process, ensuring prompt and accurate management. Early intervention is critical in the management of childhood AIS. Due to the critical time window, the question if mechanical thrombectomy is feasible and beneficial should be addressed as fast as possible. Early initiation of antiplatelet or anticoagulation therapy and, in select cases, thrombolysis can help restore blood flow and minimize long-term neurological damage. Additionally, rehabilitation should start as soon as possible to optimize recovery and improve functional outcomes. In conclusion, childhood AIS is a growing concern. Understanding the increasing incidence, age distribution, risk factors, clinical presentation, diagnostic approach, and management strategies is crucial for optimized management of these patients.

Identification of the first homozygous intragenic deletion in the YY1AP1 gene in a consanguineous family: New insights into the phenotypic variability associated with Grange syndrome

Grange syndrome (GRNG-MIM#135580) is a rare recessive disorder associating variable features including diffuse vascular stenosis, brachysyndactyly, osteopenia with increased bone fragility, cardiac malformations, and variable developmental delay. Since its first description in 1998, only 15 individuals from 10 families have been reported, carrying homozygous or compound heterozygous frameshift or nonsense variants in YY1AP1. In a patient with cutaneous and bone syndactyly and a hemorrhagic stroke at the age of 16 months, consistent with a clinical diagnosis of GRNG, we performed exome sequencing after negative array-CGH and congenital limb malformation panel results. Copy number variant analysis from exome data identified a homozygous intragenic out-of-frame deletion of 1.84 kb encompassing exons seven and eight of YY1AP1, confirming a molecular diagnosis of GRNG. Genetic counseling led to the identification of additional family members compatible with GRNG. Here, we provide new insights into the phenotypic variability associated with GRNG and highlight the utility of the detection of small copy number variants to identify the molecular causes of heterogeneous malformative genetic disorders.

Grange syndrome due to homozygous YY1AP1 missense rare variants

Grange syndrome (OMIM 602531) is an autosomal recessive condition characterized by severe early onset vascular occlusive disease and variable penetrance of brachydactyly, syndactyly, bone fragility, and learning disabilities. Grange syndrome is caused by homozygous or compound heterozygous loss-of-function variants in the YYA1P1 gene. We report on the case of a 53-year old female with novel homozygous missense variants in YYA1P1 (c.1079C>T, p.Pro360Leu), presenting with a history of brachysyndactyly, hypertension, and ischemic stroke. Imaging studies revealed stenosis of the bilateral internal carotid with extensive collateralization of cerebral vessels in a moyamoya-like pattern, along with stenosis in the splenic, common hepatic, celiac, left renal, and superior mesenteric arteries. Functional studies conducted with the patient's dermal fibroblasts suggest that the p.Pro360Leu variant decreases the stability of the YY1AP1 protein. This is the first report of a missense variant associated with Grange syndrome characterized by later onset of vascular disease and a lack of developmental delay and bone fragility.

Hemorrhagic stroke and renovascular hypertension with Grange syndrome arising from a novel pathogenic variant in YY1AP1

Pediatric hypertension can cause hypertensive emergencies, including hemorrhagic stroke, contributing to rare but serious childhood morbidity and mortality. Renovascular hypertension (RVH) is one of the major causes of secondary hypertension in children. Grange syndrome (MIM#602531) is a rare disease characterized by multiple stenosis or occlusion of the renal, abdominal, coronary, and cerebral arteries, which can cause phenotypes of RVH and fibromuscular dysplasia (MIM#135580). We report the case of a 7-year-old girl with Grange syndrome who showed RVH and multiple seizure episodes. At 1 year of age, she experienced seizures and sequential hemiparesis caused by a left thalamic hemorrhage without cerebral vascular anomalies. Chronic hypertension was observed, and abdominal computed tomography angiography showed characteristic bilateral renal artery stenosis. Whole-exome sequencing revealed a novel homozygous pathogenic variant in the YY1AP1 gene (NM_001198903.1: c.1169del: p.Lys390Argfs*12). Biallelic YY1AP1 mutations are known to cause Grange syndrome. Unlike previously reported patients, our patient presented with intracerebral hemorrhagic stroke without anomalous brain artery or bone fragility. The phenotype in our patient may help better understand this ultra-rare syndrome. Grange syndrome should be considered in patients presenting with childhood-onset hypertension and/or hemorrhagic stroke for early clinical intervention.

Identification of pathogenic YY1AP1 splice variants in siblings with Grange syndrome by whole exome sequencing

Grange syndrome is an autosomal recessive condition characterized by arterial occlusions and hypertension. Syndactyly, brachydactyly, bone fragility, heart defects, and learning disabilities have also been reported. Loss‐of‐function variants in YY1AP1 have only recently been associated with Grange syndrome. YY1AP1 encodes for the transcription coactivator yin yang 1‐associated protein 1 which regulates smooth muscle cell proliferation and differentiation. We here report on three siblings with steno‐occlusive arterial disorder and syndactyly in two of them. Whole exome sequencing including near‐splice regions led to the identification of two intronic YY1AP1 variants which were predicted to interfere with normal splicing. Sanger sequencing demonstrated compound‐heterozygosity in all affected siblings. RT‐PCR analyses confirmed skipping of exon 6 on one allele and exonization of 22 bp in intron 6 on the other. This is the first report of biallelic YY1AP1 variants in noncoding regions and just the second family with multiple affected siblings. Therefore, our report further delineates the phenotypic spectrum of Grange syndrome.

Loss-of-Function Mutations in YY1AP1 Lead to Grange Syndrome and a Fibromuscular Dysplasia-Like Vascular Disease

Fibromuscular dysplasia (FMD) is a heterogeneous group of non-atherosclerotic and non-inflammatory arterial diseases that primarily involves the renal and cerebrovascular arteries. Grange syndrome is an autosomal-recessive condition characterized by severe and early-onset vascular disease similar to FMD and variable penetrance of brachydactyly, syndactyly, bone fragility, and learning disabilities. Exome-sequencing analysis of DNA from three affected siblings with Grange syndrome identified compound heterozygous nonsense variants in YY1AP1, and homozygous nonsense or frameshift YY1AP1 variants were subsequently identified in additional unrelated probands with Grange syndrome. YY1AP1 encodes yin yang 1 (YY1)-associated protein 1 and is an activator of the YY1 transcription factor. We determined that YY1AP1 localizes to the nucleus and is a component of the INO80 chromatin remodeling complex, which is responsible for transcriptional regulation, DNA repair, and replication. Molecular studies revealed that loss of YY1AP1 in vascular smooth muscle cells leads to cell cycle arrest with decreased proliferation and increased levels of the cell cycle regulator p21/WAF/CDKN1A and disrupts TGF-β-driven differentiation of smooth muscle cells. Identification of YY1AP1 mutations as a cause of FMD indicates that this condition can result from underlying genetic variants that significantly alter the phenotype of vascular smooth muscle cells.