Arterial aneurysm and dissection: toward the evolving phenotype of Tatton-Brown-Rahman syndrome.

BACKGROUND: Tatton-Brown-Rahman syndrome (TBRS) is a rare disorder, caused by DNMT3A heterozygous pathogenic variants, and first described in 2014. TBRS is characterised by overgrowth, intellectual disability, facial dysmorphism, hypotonia and musculoskeletal features, as well as neurological and psychiatric features. Cardiac manifestations have also been reported, mainly congenital malformations such as atrial septal defect, ventricular septal defect and cardiac valvular disease. Aortic dilatation has rarely been described. METHODS: Here we have undertaken a detailed clinical and molecular description of eight previously unreported individuals, who had TBRS and arterial dilatation and/or dissection, mainly thoracic aortic aneurysm (TAA). We have also reviewed the seven previously published cases of TAA in individuals with TBRS to try to better delineate the vascular phenotype and to determine specific follow-up for this condition. RESULTS: We include eight new patients with TBRS who presented with arterial aneurysms mainly involving aorta. Three of these patients presented with dissection that required critical surgery. CONCLUSIONS: Arterial aneurysms and dissections are a potentially lethal, age-dependent manifestation. The prevalence of aortic disease in individuals with TBRS is far in excess of that expected in the general population. This cohort, together with individuals previously published, illustrates the importance to consider dilatation/dissection, mainly in aorta but also in other arteries. Arterial vascular weakness may therefore also be a cardinal feature of TBRS and vascular surveillance is recommended.

Genome Analysis in Sick Neonates and Infants: High-yield Phenotypes and Contribution of Small Copy Number Variations.

OBJECTIVE: To delineate the diagnostic efficacy of medical exome, whole exome, and whole genome sequencing according to primary symptoms, the contribution of small copy number variations, and the impact of molecular diagnosis on clinical management. STUDY DESIGN: This was a prospective study of 17 tertiary care centers in Japan, conducted between April 2019 and March 2021. Critically ill neonates and infants less than 6 months of age were recruited in neonatal intensive care units and in outpatient clinics. The patients underwent medical exome, whole exome, or whole genome sequencing as the first tier of testing. Patients with negative results after medical exome or whole exome sequencing subsequently underwent whole genome sequencing. The impact of molecular diagnosis on clinical management was evaluated through contacting primary care physicians. RESULTS: Of the 85 patients, 41 (48%) had positive results. Based on the primary symptoms, patients with metabolic phenotypes had the highest diagnostic yield (67%, 4/6 patients), followed by renal (60%, 3/5 patients), and neurologic phenotypes (58%, 14/24 patients). Among them, 4 patients had pathogenic small copy number variations identified using whole genome sequencing. In the 41 patients with a molecular diagnosis, 20 (49%) had changes in clinical management. CONCLUSIONS: Genome analysis for critically ill neonates and infants had a high diagnostic yield for metabolic, renal, and neurologic phenotypes. Small copy number variations detected using whole genome sequencing contributed to the overall molecular diagnosis in 5% of all the patients. The resulting molecular diagnoses had a significant impact on clinical management.

Two Japanese patients with Noonan syndrome-like disorder with loose anagen hair 2.

Noonan syndrome-like disorder with loose anagen hair (NSLH) is a rare disease characterized by typical features of Noonan syndrome with additional findings of relative or absolute macrocephaly, loose anagen hair, and a higher incidence of intellectual disability. NSLH1 is caused by a heterozygous mutation in the SHOC2 gene on chromosome 10q25, and NLSH2 is caused by a heterozygous mutation in the Protein phosphatase one catalytic subunit beta (PPP1CB) gene on chromosome 2p23. Protein phosphatase1 (PP1), encoded by PPP1CB, forms a complex with SHOC2 and dephosphorylates RAFs, which results in activation of the signaling cascade and contribution to Noonan syndrome pathogenesis. Here, we report two genetically confirmed Japanese patients with NSLH2 having the same de novo mutation in PPP1CB presenting prominent-hyperteloric-appearing eyes and a tall forehead similar to individuals carrying a mutation in PPP1CB, c.146C > G; p.Pro49Arg, which is different from typical facial features of Noonan syndrome. They also showed short stature, absolute macrocephaly, and loose anagen hair like NSLH1: however, growth hormone deficiency often seen in NSLH1 caused by SHOC2 mutation was absent. Although a number of Noonan syndrome and NSLH1 patients have shown blunted or no response to GH therapy, linear growth was promoted by recombinant human growth hormone (rhGH) in one of our patients. Since another NSLH2 patient with good response to rhGH treatment was reported, rhGH therapy may be effective in patients with NSLH2.

Severe neuroglycopenic symptoms due to nonketotic hypoglycemia in children with cardio-facio-cutaneous syndrome.

Cardio-facio-cutaneous syndrome (CFC) (OMIM 115150) is a congenital disease caused by constitutive activation of the Raf/MEK/ERK signaling cascade. Unlike aspects of morphological anomalies, metabolic functions related to the disease have garnered little attention. We present severe neuroglycopenic symptoms due to nonketotic hypoglycemia in two children with CFC (Case 1, a 4-year-old male with c.389A > G heterozygous variant in MAP2K1; Case 2, a 3-year-old male with c.770A > G heterozygous variant in BRAF). Case 1 exhibited a nonketotic hypoglycemic coma and clustered left-hemispheric convulsions despite receiving infusion therapy, leading to severe sequelae with choreoathetosis. Brain magnetic resonance imaging of Case 1 showed T2-elongation with restricted diffusion on the bilateral basal ganglia and thalamus, with the dominance of the right putamen. Case 2 presented a prolonged generalized seizure as an initial clinical symptom but fully recovered. The presence of growth hormone and cortisol deficiency was ruled out in both cases. Blood spots acylcarnitine profiles excluded the co-occurrence of mitochondrial HMG-CoA synthase deficiency and HMG-CoA lyase deficiency. These cases demonstrate the potential vulnerability to nonketotic hypoglycemia, especially during lipid shortages. As children with CFC frequently have difficulties feeding, we suggest great attention should be paid to the potential risk of severe nonketotic hypoglycemia.

Rothmund-Thomson syndrome investigated by two nationwide surveys in Japan.

BACKGROUND: Rothmund-Thomson syndrome (RTS) is an autosomal recessive genetic disorder characterized by poikiloderma of the face, small stature, sparse scalp hair, juvenile cataract, radial aplasia, and predisposition to cancers. Due to the rarity of RTS, the situation of patients with RTS in Japan has not been elucidated. METHODS: In 2010 and 2020, following the results of a primary questionnaire survey, a secondary questionnaire survey on RTS was conducted nationwide to investigate the number of RTS cases and their associated skin lesions, bone lesions, other clinical features, and quality of life in Japan. RESULTS: In 2010 and 2020, 10 and eight patients with RTS were recruited, respectively. Skin lesions such as poikiloderma, erythema, pigmentation, and abnormal scalp hair were observed in almost all cases. Bone lesions were observed in four cases in the 2010 and 2020 surveys, respectively. Two cases had mutations in the RECQL4 gene in the 2020 survey. CONCLUSIONS: Two nationwide surveys have shown the actual situation of patients with RTS in Japan. Cutaneous and bone manifestations are important for the diagnosis of RTS. However, many patients have no RECQL4 mutations. The novel causative gene of RTS should be further elucidated.

Severe Liver Disorder Following Liver Transplantation in STING-Associated Vasculopathy with Onset in Infancy.

PURPOSE: STING-associated vasculopathy with onset in infancy (SAVI) is a type-I interferonopathy, characterized by systemic inflammation, peripheral vascular inflammation, and pulmonary manifestations. There are three reports of SAVI patients developing liver disease, but no report of a SAVI patient requiring liver transplantation. Therefore, the relevance of liver inflammation is unclear in SAVI. We report a SAVI patient who developed severe liver disorder following liver transplantation. METHODS: SAVI was diagnosed in a 4-year-old girl based on genetic analysis by whole-exome sequencing. We demonstrated clinical features, laboratory findings, and pathological examination of her original and transplanted livers. RESULTS: At 2 months of age, she developed bronchitis showing resistance to bronchodilators and antibiotics. At 10 months of age, she developed liver dysfunction with atypical cholangitis, which required liver transplantation at 1 year of age. At 2 years of age, multiple biliary cysts developed in the transplanted liver. At 3.9 years of age, SAVI was diagnosed by whole-exome sequencing. Inflammatory cells from the liver invaded the stomach wall directly, leading to fatal gastrointestinal bleeding unexpectedly at 4.6 years of age. In pathological findings, there were no typical findings of liver abscess, vasculitis, or graft rejection, but biliary cysts and infiltration of inflammatory cells, including plasmacytes around the bile duct area, in the transplanted liver were noted, which were findings similar to those of her original liver. CONCLUSION: Although further studies to clarify the mechanisms of the various liver disorders described in SAVI patients are needed, inflammatory liver manifestations may be amplified in the context of SAVI.

Prevalence of Immunological Defects in a Cohort of 97 Rubinstein-Taybi Syndrome Patients.

Although recurrent infections in Rubinstein-Taybi syndrome (RSTS) are common, and probably multifactorial, immunological abnormalities have not been extensively described with only isolated cases or small case series of immune deficiency and dysregulation having been reported. The objective of this study was to investigate primary immunodeficiency (PID) and immune dysregulation in an international cohort of patients with RSTS. All published cases of RSTS were identified. The corresponding authors and researchers involved in the diagnosis of inborn errors of immunity or genetic syndromes were contacted to obtain up-to-date clinical and immunological information. Ninety-seven RSTS patients were identified. For 45 patients, we retrieved data from the published reports while for 52 patients, a clinical update was provided. Recurrent or severe infections, autoimmune/autoinflammatory complications, and lymphoproliferation were observed in 72.1%, 12.3%, and 8.2% of patients. Syndromic immunodeficiency was diagnosed in 46.4% of individuals. Despite the broad heterogeneity of immunodeficiency disorders, antibody defects were observed in 11.3% of subjects. In particular, these patients presented hypogammaglobulinemia associated with low B cell counts and reduction of switched memory B cell numbers. Immunoglobulin replacement therapy, antibiotic prophylaxis, and immunosuppressive treatment were employed in 16.4%, 8.2%, and 9.8% of patients, respectively. Manifestations of immune dysfunctions, affecting mostly B cells, are more common than previously recognized in patients with RSTS. Full immunological assessment is warranted in these patients, who may require detailed investigation and specific supportive treatment. Graphical Abstract.

Consecutive medical exome analysis at a tertiary center: Diagnostic and health-economic outcomes.

The utility of whole exome analysis has been extensively demonstrated in research settings, but its clinical utility as a first-tier genetic test has not been well documented from diagnostic and health economic standpoints in real-life clinical settings. We performed medical exome analyses focusing on a clinically interpretable portion of the genome (4,813 genes) as a first-tier genetic test for 360 consecutive patients visiting a genetics clinic at a tertiary children's hospital in Japan, over a 3-year period. Bioinformatics analyses were conducted using standard software. A molecular diagnosis was made in 171 patients involving a total of 107 causative genes. Among these 107 causative genes, 57 genes were classified as genes with potential organ-specific interventions and management strategies. Clinically relevant results were obtained in 26% of the total cohort and 54% of the patients with a definitive molecular diagnosis. Performing the medical exome analysis at the time of the initial visit to the tertiary center, rather than after visits to pertinent specialists, brain MRI examination, and G-banded chromosome testing, would have reduced the financial cost by 197 euros according to retrospective calculation under multiple assumption. The present study demonstrated a high diagnostic yield (47.5%) for singleton medical exome analysis as a first-tier test in a real-life setting. Medical exome analysis yielded clinically relevant information in a quarter of the total patient cohort. The application of genomic testing during the initial visit to a tertiary medical center could be a rational approach to the diagnosis of patients with suspected genetic disorders.

Biallelic mutations in LARS2 can cause Perrault syndrome type 2 with neurologic symptoms.

Perrault syndrome represents a genetically heterogeneous disorder characterized by sensorineural hearing loss in males and females and ovarian dysfunction in females. Causative genes include HARS2, HSD17B4, CLPP, C10orf2, and LARS2. Some patients with Perrault syndrome exhibit neurologic features including learning disability, cerebellar ataxia, and peripheral neuropathy and are classified as type 2 and are clinically separate from those without neurological symptoms other than a hearing loss (type 1). To date, all reported patients with LARS2 mutations (15 patients in 8 families) have been classified as type 1. Here, we report female siblings with biallelic mutations in LARS2, p.Glu294Lys, and p.Thr519Met, who were classified as type 2. The proposita developed progressive sensorineural hearing loss at 18 months and pervasive developmental disorder at 8 years, with repetitive behavior, insistence on sameness, attention deficit, tic, irritability, and an ataxic gait. At age 15 years, she was diagnosed as having primary amenorrhea with elevated FSH and LH and a decreased estradiol; ultrasound and magnetic resonance imaging examinations revealed a small uterus and no detectable ovaries. The proposita's younger sister presented with neonatal sensorineural hearing loss and a mild delay in motor and speech development. She was diagnosed as having primary amenorrhea with endocrinologic and radiographic findings that were comparable to those of her sister. She had difficulty with reading comprehension, and had trouble with open-ended test questions at 12 years of age. We concluded that Perrault syndrome patients with LARS2 mutations are at risk for neurologic problems, despite previous notions otherwise.

Timothy syndrome-like condition with syndactyly but without prolongation of the QT interval.

Timothy syndrome is characterized by a unique combination of a prolongation of the corrected QT interval of the electrocardiogram and bilateral cutaneous syndactyly of the fingers and the toes and is caused by heterozygous mutations in CACNA1C, a gene encoding a calcium channel. After the discovery of the CACNA1C gene as the causative gene for Timothy syndrome, patients with CACNA1C mutations with QT prolongation but without syndactyly were described. Here, we report a 5-year-old female patient with cutaneous syndactyly, developmental delay, and pulmonary hypertension. Exome analysis showed a previously undescribed de novo heterozygous mutation in the CACNA1C gene, p.Arg1024Gly. To our knowledge, this patient is the first to exhibit syndactyly and to carry a CACNA1C mutation but to not have QT prolongation, which has long been considered an obligatory feature of Timothy syndrome.

Temple syndrome: comprehensive molecular and clinical findings in 32 Japanese patients.

PurposeTemple syndrome (TS14) is a rare imprinting disorder caused by aberrations at the 14q32.2 imprinted region. Here, we report comprehensive molecular and clinical findings in 32 Japanese patients with TS14.MethodsWe performed molecular studies for TS14 in 356 patients with variable phenotypes, and clinical studies in all TS14 patients, including 13 previously reported.ResultsWe identified 19 new patients with TS14, and the total of 32 patients was made up of 23 patients with maternal uniparental disomy (UPD(14)mat), six patients with epimutations, and three patients with microdeletions. Clinical studies revealed both Prader-Willi syndrome (PWS)-like marked hypotonia and Silver-Russell syndrome (SRS)-like phenotype in 50% of patients, PWS-like hypotonia alone in 20% of patients, SRS-like phenotype alone in 20% of patients, and nonsyndromic growth failure in the remaining 10% of patients in infancy, and gonadotropin-dependent precocious puberty in 76% of patients who were pubescent or older.ConclusionThese results suggest that TS14 is not only a genetically diagnosed entity but also a clinically recognizable disorder. Genetic testing for TS14 should be considered in patients with growth failure plus both PWS-like hypotonia and SRS-like phenotypes in infancy, and/or precocious puberty, as well as a familial history of Kagami-Ogata syndrome due to maternal microdeletion at 14q32.2.

The clinical characteristics of Asian patients with classical-type Hutchinson-Gilford progeria syndrome.

Hutchinson-Gilford progeria syndrome (HGPS) is an extremely rare genetic disorder that shows a characteristic progeria phenotype. We conducted a questionnaire survey of 1173 tertiary hospitals in Japan and reviewed the academic reports, to identify the characteristics of Asian patients with classical HGPS. As a result, four Japanese patients were identified; this was estimated to account for approximately two-third of the prevalence in Japan. Three Asian patients who had definitively been diagnosed with classical HGPS were identified in the literature; in total, the clinical characteristics of seven patients were evaluated. Most of the clinical phenotypes of Asian patients were essentially similar to those of patients of other ethnicities, such as sclerodermatous skin, growth failure, loss of scalp hair or severe complications of cardiovascular and cerebral ischemic disease. In conclusion, to circumvent or minimalize severe vascular complication, an early diagnosis, careful observation and, promisingly, new intervention with farnesylation inhibitors may improve the prognosis of classical HGPS patients.

Acute myeloid leukemia-associated DNMT3A p.Arg882His mutation in a patient with Tatton-Brown-Rahman overgrowth syndrome as a constitutional mutation.

DNA methylation plays a critical role in both embryonic development and tumorigenesis and is mediated through various DNA methyltransferases. Constitutional mutations in the de novo DNA methyltransferase DNMT3A cause a recently identified Tatton-Brown-Rahman overgrowth syndrome (TBRS). Somatically acquired mutations in DNMT3A are causally associated with acute myeloid leukemia (AML), and p.Arg882His represents the most prevalent hotspot. So far, no patients with TBRS have been reported to have subsequently developed AML. Here, we report a live birth and the survival of a female with the TBRS phenotype who had a heterozygous constitutional DNMT3A mutation at the AML somatic mutation hotspot p.Arg882His in her DNA from peripheral blood and buccal tissue. Her characteristic features at birth included hypotonia, narrow palpebral fissures, ventricular septal defect, umbilical hernia, sacral cyst, Chiari type I anomaly. At the age of 6 years, she exhibited overgrowth (> 3 SD) and round face and intellectual disability. This report represents the first documentation of the same variant (DNMT3A p.Arg882His) as both the constitutional mutation associated with TBRS and the somatic mutation hotspot of AML. The observation neither confirms nor denies the notion that mutations responsible for TBRS and those for AML might share the same mode of action. Larger data sets are required to determine whether TBRS patients with constitutional DNMT3A mutations are at an increased risk for AML. © 2016 Wiley Periodicals, Inc.

The outcomes of 31 cases of trisomy 13 diagnosed in utero with various management options.

There are few reports on the prognosis of prenatally diagnosed trisomy 13 in relation to postnatal management. The aim of this study was to report on the prenatal and postnatal outcomes and postnatal management of trisomy 13 fetuses that were prenatally diagnosed at our center between 2003 and 2015. The data were retrospectively reviewed from medical records. Of the 31 cases of trisomy 13, 12 patients were diagnosed before 22 weeks of gestation, and 19 were diagnosed at or after 22 weeks of gestation. Nine families opted for termination of the pregnancy, 14 fetuses died, and 8 were born alive. Aggressive treatment was requested in two of the live births, with one patient achieving long-term survival (7 years). The other died during infancy (Day 61). One out of four who received palliative treatment is alive at two years of age with only nutrition supplementation. These three patients who achieved neonatal survival had few structural anomalies. Fetal death and early neonatal death are common in trisomy 13; however, fetuses that receive medical treatment for cases without major ultrasound abnormalities may achieve neonatal survival. Therefore, it is useful to provide comprehensive information, including precise ultrasound findings and treatment options, to parents with trisomy 13 fetuses during genetic counseling.

Rubinstein-Taybi syndrome.

Rubinstein-Taybi syndrome (RTS) is characterized by moderate to severe intellectual disability, distinctive facial features, and broad thumbs and great toes. RTS is caused by haploinsufficiency of CREBBP or EP300 gene.

Mutations in SERPINB7, encoding a member of the serine protease inhibitor superfamily, cause Nagashima-type palmoplantar keratosis.

"Nagashima-type" palmoplantar keratosis (NPPK) is an autosomal recessive nonsyndromic diffuse palmoplantar keratosis characterized by well-demarcated diffuse hyperkeratosis with redness, expanding on to the dorsal surfaces of the palms and feet and the Achilles tendon area. Hyperkeratosis in NPPK is mild and nonprogressive, differentiating NPPK clinically from Mal de Meleda. We performed whole-exome and/or Sanger sequencing analyses of 13 unrelated NPPK individuals and identified biallelic putative loss-of-function mutations in SERPINB7, which encodes a cytoplasmic member of the serine protease inhibitor superfamily. We identified a major causative mutation of c.796C>T (p.Arg266(∗)) as a founder mutation in Japanese and Chinese populations. SERPINB7 was specifically present in the cytoplasm of the stratum granulosum and the stratum corneum (SC) of the epidermis. All of the identified mutants are predicted to cause premature termination upstream of the reactive site, which inhibits the proteases, suggesting a complete loss of the protease inhibitory activity of SERPINB7 in NPPK skin. On exposure of NPPK lesional skin to water, we observed a whitish spongy change in the SC, suggesting enhanced water permeation into the SC due to overactivation of proteases and a resultant loss of integrity of the SC structure. These findings provide an important framework for developing pathogenesis-based therapies for NPPK.

Mutations in B3GALT6, which encodes a glycosaminoglycan linker region enzyme, cause a spectrum of skeletal and connective tissue disorders.

Proteoglycans (PGs) are a major component of the extracellular matrix in many tissues and function as structural and regulatory molecules. PGs are composed of core proteins and glycosaminoglycan (GAG) side chains. The biosynthesis of GAGs starts with the linker region that consists of four sugar residues and is followed by repeating disaccharide units. By exome sequencing, we found that B3GALT6 encoding an enzyme involved in the biosynthesis of the GAG linker region is responsible for a severe skeletal dysplasia, spondyloepimetaphyseal dysplasia with joint laxity type 1 (SEMD-JL1). B3GALT6 loss-of-function mutations were found in individuals with SEMD-JL1 from seven families. In a subsequent candidate gene study based on the phenotypic similarity, we found that B3GALT6 is also responsible for a connective tissue disease, Ehlers-Danlos syndrome (progeroid form). Recessive loss-of-function mutations in B3GALT6 result in a spectrum of disorders affecting a broad range of skeletal and connective tissues characterized by lax skin, muscle hypotonia, joint dislocation, and spinal deformity. The pleiotropic phenotypes of the disorders indicate that B3GALT6 plays a critical role in a wide range of biological processes in various tissues, including skin, bone, cartilage, tendon, and ligament.

SNP array screening of cryptic genomic imbalances in 450 Japanese subjects with intellectual disability and multiple congenital anomalies previously negative for large rearrangements.

Intellectual disability (ID) is a heterogeneous condition affecting 2-3% of the population, often associated with multiple congenital anomalies (MCA). The genetic cause remains largely unexplained for most cases. To investigate the causes of ID/MCA of unknown etiology in the Japanese population, 645 subjects have been recruited for the screening of pathogenic copy-number variants (CNVs). Two screenings using bacterial artificial chromosome (BAC) arrays were previously performed, which identified pathogenic CNVs in 133 cases (20.6%; Hayashi et al., J. Hum. Genet., 2011). Here, we present the findings of the third screening using a single-nucleotide polymorphism (SNP) array, performed in 450 negative cases from our previous report. Pathogenic CNVs were found in 22 subjects (4.9%), in which 19 CNVs were located in regions where clinical significance had been previously established. Among the 22 cases, we identified PPFIA2 as a novel candidate gene for ID. Analysis of copy-neutral loss of heterozygosity (CNLOH) detected one case in which the CNLOH regions seem to be significant. The SNP array detected a modest fraction of small causative CNVs, which is explained by the fact that the majority of causative CNVs have larger sizes, and those had been mostly identified in the two previous screenings.

Large-scale mutational analysis in the EXT1 and EXT2 genes for Japanese patients with multiple osteochondromas.

BACKGROUND: Multiple osteochondroma (MO) is an autosomal dominant skeletal disorder characterized by the formation of multiple osteochondromas, and exostosin-1 (EXT1) and exostosin-2 (EXT2) are major causative genes in MO. In this study, we evaluated the genetic backgrounds and mutational patterns in Japanese families with MO. RESULTS: We evaluated 112 patients in 71 families with MO. Genomic DNA was isolated from peripheral blood leucocytes. The exons and exon/intron junctions of EXT1 and EXT2 were directly sequenced after PCR amplification. Fifty-two mutations in 47 families with MO in either EXT1 or EXT2, and 42.3% (22/52) of mutations were novel mutations. Twenty-nine families (40.8%) had mutations in EXT1, and 15 families (21.1%) had mutations in EXT2. Interestingly, three families (4.2%) had mutations in both EXT1 and EXT2. Twenty-four families (33.8%) did not exhibit mutations in either EXT1 or EXT2. With regard to the types of mutations identified, 59.6% of mutations were inactivating mutations, and 38.5% of mutations were missense mutations. CONCLUSIONS: We found that the prevalence of EXT1 mutations was greater than that of EXT2 mutations in Japanese MO families. Additionally, we identified 22 novel EXT1 and EXT2 mutations in this Japanese MO cohort. This study represents the variety of genotype in MO.