Expanding the Mutational Spectrum of CRLF1 in Crisponi/CISS1 Syndrome

Crisponi syndrome (CS) and cold‐induced sweating syndrome type 1 (CISS1) share clinical characteristics, such as dysmorphic features, muscle contractions, scoliosis, and cold‐induced sweating, with CS patients showing a severe clinical course in infancy involving hyperthermia associated with death in most cases in the first years of life. To date, 24 distinct CRLF1 mutations have been found either in homozygosity or in compound heterozygosity in CS/CISS1 patients, with the highest prevalence in Sardinia, Turkey, and Spain. By reporting 11 novel CRLF1 mutations, here we expand the mutational spectrum of CRLF1 in the CS/CISS1 syndrome to a total of 35 variants and present an overview of the different molecular and clinical features of all of them. To catalog all the 35 mutations, we created a CRLF1 mutations database, based on the Leiden Open (source) Variation Database (LOVD) system ( https://grenada.lumc.nl/LOVD2/mendelian_genes/variants ). Overall, the available functional and clinical data support the fact that both syndromes actually represent manifestations of the same autosomal‐recessive disorder caused by mutations in the CRLF1 gene. Therefore, we propose to rename the two overlapping entities with the broader term of Crisponi/CISS1 syndrome.     

Three new cases of Crisponi /cold induced sweating syndrome (CS/CISS1) in Turkish families

Crisponi syndrome/Cold Induced Sweating Syndrome 1 (CS/CISS1) is a rare, autosomal recessive, multisystemic disease. Hyperthermia attacks, abnormal contractions in the muscles of the face and oropharynx, respiratory distress, camptodactyly, and swallowing difficulty are the main features of the condition in the neonatal period. Patients experience cold-induced sweating attacks and progressive kyphoscoliosis in childhood and adolescence. Mutations in the cytokine receptor like factor 1 (CRLF1) gene causes the CISS1 (Cold- induced sweating syndrome type 1) disease (over 95% of patients). CRLF1 is located in the ciliary neurotrophic factor receptor (CNTFR) pathway, which plays an important role in development and maintenance of neurons in the nervous system. In this study three patients from Turkey, clinically and molecularly diagnosed with CS/CISS1, are presented. Hyperthermia, swallowing difficulty, camptodactyly and pursing of the lips were present in all patients, and foot deformity in one patient. In the first patient a homozygous nonsense mutation NM_004750.5: c.531G > A; p.(Trp177Ter) in the 4th exon was detected. In the second patient a homozygous nonsense mutation NM_004750.5: c.776C > A; p.(Ser259Ter) in the 5th exon was detected. The third patient was homozygous for a missense mutation NM_004750.5: c.935G > T; p.(Arg312Leu) in the 6th exon. Early diagnosis is very important in this syndrome since most patients die in the neonatal period. Therefore, physicians should be suspicious for this disease in patients with dysmorphic features, hyperthermia attacks, camptodactyly, pursing of lips while crying, and swallowing difficulty.     

Differential secretion of the mutated protein is a major component affecting phenotypic severity in CRLF1-associated disorders

Crisponi syndrome (CS) and cold-induced sweating syndrome type 1 (CISS1) are disorders caused by mutations in CRLF1. The two syndromes share clinical characteristics, such as dysmorphic features, muscle contractions, scoliosis and cold-induced sweating, with CS patients showing a severe clinical course in infancy involving hyperthermia, associated with death in most cases in the first years of life. To evaluate a potential genotype/phenotype correlation and whether CS and CISS1 represent two allelic diseases or manifestations at different ages of the same disorder, we carried out a detailed clinical analysis of 19 patients carrying mutations in CRLF1. We studied the functional significance of the mutations found in CRLF1, providing evidence that phenotypic severity of the two disorders mainly depends on altered kinetics of secretion of the mutated CRLF1 protein. On the basis of these findings, we believe that the two syndromes, CS and CISS1, represent manifestations of the same disorder, with different degrees of severity. We suggest renaming the two genetic entities CS and CISS1 with the broader term of Sohar-Crisponi syndrome.     

A new Turkish infant with clinical features of CS/CISS1 syndrome and homozygous CRLF1 mutation

Cold-induced sweating syndrome (CISS) is a rare autosomal recessive disorder characterized by profuse sweating at cold environmental temperatures, facial dysmorphism and skeletal features. The infantile presentation of CISS, referred to as Crisponi syndrome (CS), is characterized by facial muscular contractures in response to slight tactile stimuli or during crying, by life-threatening feeding difficulties caused by suck and swallow inabilities, and by intermittent hyperthermia. High febrile crises can lead to death within the first months of life. In preadolescence, surviving patients develop kyphoscoliosis and abnormal sweating.CISS is a genetically heterogeneous disorder caused by mutations in CRLF1 in more than 90 percent of patients (CISS1) and by mutations in CLCF1 in the remaining patients (CISS2). It is now well demonstrated that all patients with an infantile-onset CS will develop CISS, confirming that CS and CISS are not “allelic disorders” but the same clinical entity described at different ages of affected patients.Here we report on a Turkish patient with a phenotype consistent with CS/CISS1 and a nonsense homozygous mutation (c.829C>T, p.R277X) in the CRLF1 gene. This mutation has already been reported in another Turkish patient with CS/CISS1.     

Crisponi/cold-induced sweating syndrome: Differential diagnosis,pathogenesis and treatment concepts

Crisponi/cold-induced sweating syndrome (CS/CISS) is an autosomal recessive disease characterized by hyperthermia, camptodactyly, feeding and respiratory difficulties often leading to sudden death in the neonatal period. The affected individuals who survived the first critical years of life, develop cold-induced sweating and scoliosis in early childhood. The disease is caused by variants in the CRLF1 or in the CLCF1 gene. Both proteins form a heterodimeric complex that acts on cells expressing the ciliary neurotrophic factor receptor (CNTFR). CS/CISS belongs to the family of “CNTFR-related disorders” showing a similar clinical phenotype. Recently, variants in other genes, including KLHL7, NALCN, MAGEL2 and SCN2A, previously linked to other diseases, have been associated with a CS/CISS-like phenotype. Therefore, retinitis pigmentosa and Bohring-Optiz syndrome-like (KLHL7), Congenital contractures of the limbs and face, hypotonia, and developmental delay syndrome (NALCN), Chitayat-Hall/Schaaf-Yang syndrome (MAGEL2), and early infantile epileptic encephalopathy-11 syndrome (SCN2A) all share an overlapping phenotype with CS/CISS, especially in the neonatal period. This review aims to summarize the existing literature on CS/CISS, focusing on the current state of differential diagnosis, pathogenesis and treatment concepts in order to achieve an accurate and rapid diagnosis. This will improve patient management and enable specific treatments for the affected individuals.     

Exome sequencing in Crisponi/cold-induced sweating syndrome–like individuals reveals unpredicted alternative diagnoses

Crisponi/cold-induced sweating syndrome (CS/CISS) is a rare autosomal recessive disorder characterized by a complex phenotype (hyperthermia and feeding difficulties in the neonatal period, followed by scoliosis and paradoxical sweating induced by cold since early childhood) and a high neonatal lethality. CS/CISS is a genetically heterogeneous disorder caused by mutations in CRLF1 (CS/CISS1), CLCF1 (CS/CISS2) and KLHL7 (CS/CISS-like). Here, a whole exome sequencing approach in individuals with CS/CISS-like phenotype with unknown molecular defect revealed unpredicted alternative diagnoses. This approach identified putative pathogenic variations in NALCN, MAGEL2 and SCN2A. They were already found implicated in the pathogenesis of other syndromes, respectively the congenital contractures of the limbs and face, hypotonia, and developmental delay syndrome, the Schaaf-Yang syndrome, and the early infantile epileptic encephalopathy-11 syndrome. These results suggest a high neonatal phenotypic overlap among these disorders and will be very helpful for clinicians. Genetic analysis of these genes should be considered for those cases with a suspected CS/CISS during neonatal period who were tested as mutation negative in the known CS/CISS genes, because an expedited and corrected diagnosis can improve patient management and can provide a specific clinical follow-up.     

Bi-allelic c.181_183delTGT in BTB domain of KLHL7 is associated with overlapping phenotypes of Crisponi/CISS1-like and Bohring-Opitz like syndrome

Biallelic pathogenic variants in KLHL7 are known to result in Crisponi syndrome (CS)/cold-induced sweating syndrome type 1 (CISS1) like phenotype and Bohring-Opitz-like syndrome. In this report, a trio whole-exome sequencing (WES) was performed in proband with cold-induced sweating, microcephaly, facial dysmorphism, spasticity, failure to thrive, pigmentary abnormalities of the retina, hypoplasia of corpus callosum and periventricular nodular heterotopia. A novel homozygous in-frame deletion was identified in exon 2 of KLHL7, affecting the BTB domain of the protein. Our findings expand the clinical and molecular spectrum of KLHL7-related disorders.     

Mutations in RIT1 cause Noonan syndrome – additional functional evidence and expanding the clinical phenotype

RASopathies are a clinically heterogeneous group of conditions caused by mutations in 1 of 16 proteins in the RAS‐mitogen activated protein kinase (RAS‐MAPK) pathway. Recently, mutations in RIT1 were identified as a novel cause for Noonan syndrome. Here we provide additional functional evidence for a causal role of RIT1 mutations and expand the associated phenotypic spectrum. We identified two de novo missense variants p.Met90Ile and p.Ala57Gly. Both variants resulted in increased MEK‐ERK signaling compared to wild‐type, underscoring gain‐of‐function as the primary functional mechanism. Introduction of p.Met90Ile and p.Ala57Gly into zebrafish embryos reproduced not only aspects of the human phenotype but also revealed abnormalities of eye development, emphasizing the importance of RIT1 for spatial and temporal organization of the growing organism. In addition, we observed severe lymphedema of the lower extremity and genitalia in one patient. We provide additional evidence for a causal relationship between pathogenic mutations in RIT1, increased RAS‐MAPK/MEK‐ERK signaling and the clinical phenotype. The mutant RIT1 protein may possess reduced GTPase activity or a diminished ability to interact with cellular GTPase activating proteins; however the precise mechanism remains unknown. The phenotypic spectrum is likely to expand and includes lymphedema of the lower extremities in addition to nuchal hygroma.     

Mutations in FGFR1 and FGFR2 cause familial and sporadic Pfeiffer syndrome

Pfeifter syndrome (PS) is an autosomal dominant skeletal disorderwhich affects the bones of the skull, hands and feet. Previously,we have mapped PS in a subset of families to chromosome 8cenby linkage analysis and demonstrated a common mutation in thefibroblast growth factor receptor-1 (FGFR1) gene in the linkedfamilies. Here we report a second locus for PS on chromosome10q25, and present evidence that mutations in the fibroblastgrowth factor receptor-2 (FGFR2) gene on 10q25 cause PS in anadditional subset of familial and sporadic cases. Three differentpoint mutations in FGFR2, which alter the same acceptor splicesite of exon B, were observed in both sporadic and familialPS. In addition, a T to C transition in exon B predicting acysteine to arginine substitution was identified in three sporadicPS individuals. Interestingly, this T to C change is identicalto a mutation in FGFR2 previously reported in Crouzon syndrome,a phenotypically similar disorder but one lacking the hand andfoot anomalies seen in PS. Our results highlight the geneticheterogeneity in PS and suggest that the molecular data willbe an important complement to the clinical phenotype in definingcraniosynostosis syndromes.     

Mutations in ERGIC1 cause Arthrogryposis multiplex congenita,neuropathic type

Arthrogryposis multiplex congenita (AMC) is heterogeneous group of disorders characterized by non‐progressive joint contractures from birth that involve more than 1 part of the body. There are various etiologies for AMC including genetic and environmental depends on the specific type, however, for most types, the cause is not fully understood. We previously reported large Israeli Arab kindred consisting of 16 patients affected with AMC neuropathic type, and mapped the locus to a 5.5 cM interval on chromosome 5qter. Using whole exome sequencing, we have now identified homozygous pathogenic variant in the ERGIC1 gene within the previously defined linked region. ERGIC1 encodes a cycling membrane protein which has a possible role in transport between endoplasmic reticulum and Golgi. We further show that this mutation was absent in more than 200 samples of healthy unrelated individuals of the Israeli Arab population. Thus, our findings expand the spectrum of hereditary AMC and suggest that abnormalities in protein trafficking may underlie AMC‐related disorders.     

PRRT2 Mutations are the major cause of benign familial infantile seizures

Mutations in PRRT2 have been described in paroxysmal kinesigenic dyskinesia (PKD) and infantile convulsions with choreoathetosis (PKD with infantile seizures), and recently also in some families with benign familial infantile seizures (BFIS) alone. We analyzed PRRT2 in 49 families and three sporadic cases with BFIS only of Italian, German, Turkish, and Japanese origin and identified the previously described mutation c.649dupC in an unstable series of nine cytosines to occur in 39 of our families and one sporadic case (77% of index cases). Furthermore, three novel mutations were found in three other families, whereas 17% of our index cases did not show PRRT2 mutations, including a large family with late‐onset BFIS and febrile seizures. Our study further establishes PRRT2 as the major gene for BFIS alone. Hum Mutat 33:1439–1443, 2012. © 2012 Wiley Periodicals, Inc.     

POLD1 Germline Mutations in Patients Initially Diagnosed with Werner Syndrome

Segmental progeroid syndromes are rare, heterogeneous disorders characterized by signs of premature aging affecting more than one tissue or organ. A prototypic example is the Werner syndrome (WS), caused by biallelic germline mutations in the Werner helicase gene (WRN). While heterozygous lamin A/C (LMNA) mutations are found in a few nonclassical cases of WS, another 10%–15% of patients initially diagnosed with WS do not have mutations in WRN or LMNA. Germline POLD1 mutations were recently reported in five patients with another segmental progeroid disorder: mandibular hypoplasia, deafness, progeroid features syndrome. Here, we describe eight additional patients with heterozygous POLD1 mutations, thereby substantially expanding the characterization of this new example of segmental progeroid disorders. First, we identified POLD1 mutations in patients initially diagnosed with WS. Second, we describe POLD1 mutation carriers without clinically relevant hearing impairment or mandibular underdevelopment, both previously thought to represent obligate diagnostic features. These patients also exhibit a lower incidence of metabolic abnormalities and joint contractures. Third, we document postnatal short stature and premature greying/loss of hair in POLD1 mutation carriers. We conclude that POLD1 germline mutations can result in a variably expressed and probably underdiagnosed segmental progeroid syndrome.     

家族性Peutz-Jeghers综合征患者LKB1基因胚系突变的分析

目的 研究家族性Peutz-Jeghers综合征患者中LKB1基因胚系突变特征.方法 收集11个Peutz-Jeghers综合征家系,各家系先证者均有典型的黏膜黑斑以及肠道错构瘤性息肉.提取先证者外周血DNA,PCR扩增LKB1基因的9个外显子及其侧翼的部分内含子序列,测序并分析其变异情况和突变性质.收集250名正常人外周血并提取DNA,聚合酶链反应-变性高效液相色谱筛查验证.结果 11个家系先证者中有8例患者LKB1基因外显子及侧翼碱基序列存在杂合性变异,变异类型共9种,包括7种点突变,1种外显子区域小片段碱基缺失以及1种侧翼内含子小片段碱基插入.其中4种考虑为病理性突变,还有4种仅为基因多态性表现,另外有1种变异性质未定.结论 LKB1基因病理性突变是中国人家族性Peutz-Jeghers综合征患者的常见病因,且以点突变为主.     

Mutations in ALDH1A3 cause microphthalmia

Microphthalmia is an important inborn error of eye development that can be associated with multisystem involvement. Anophthalmia is more severe and rarer. Single mutations in an expanding list of genes are known to cause this spectrum of anomaly. In one branch of a multiplex family with microphthalmia and anophthalmia, autozygome analysis excluded all known microphthalmia genes at the time of doing this study. Exome sequencing and autozygome filtration identified a novel homozygous variant in ALDH1A3. Subsequently, we identified another homozygous variant in 2 of the 10 probands with microphthalmia we specifically screened for mutations in ALDH1A3. Interestingly, the other branch of the original family was found to segregate anophthalmia/syndactyly with a novel homozygous SMOC1 variant. Our data support the very recent and independent identification of ALDH1A3 as a disease gene in microphthalmia. Locus heterogeneity should be considered in consanguineous families even for extremely rare phenotypes.     

A novel mutation in GPIHBP1 causes familial chylomicronemia syndrome

Familial chylomicronemia syndrome is characterized by severe elevation in serum triglycerides and an increased risk of acute pancreatitis. Although familial chylomicronemia syndrome is mainly caused by mutations in the lipoprotein lipase (LPL) gene, few causal mutations in other genes (ie, APOC2, APOA5, LMF1, and GPIHBP1) have also been reported. In this case report, we present the discovery of a novel mutation in the glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1 (GPIHBP1) gene and discuss its pathogenicity through a familial segregation study.