TRAPPC6B biallelic variants cause a neurodevelopmental disorder with TRAPP II and trafficking disruptions

Highly conserved transport protein particle (TRAPP) complexes regulate subcellular trafficking pathways. Accurate protein trafficking has been increasingly recognized to be critically important for normal development, particularly in the nervous system. Variants in most TRAPP complex subunits have been found to lead to neurodevelopmental disorders with diverse but overlapping phenotypes. We expand on limited prior reports on TRAPPC6B with detailed clinical and neuroradiologic assessments, and studies on mechanisms of disease, and new types of variants. We describe 29 additional patients from 18 independent families with biallelic variants in TRAPPC6B. We identified seven homozygous nonsense (n = 12 patients) and eight canonical splice-site variants (n = 17 patients). In addition, we identified one patient with compound heterozygous splice-site/missense variants with a milder phenotype and one patient with homozygous missense variants. Patients displayed non-progressive microcephaly, global developmental delay/intellectual disability, epilepsy and absent expressive language. Movement disorders including stereotypies, spasticity and dystonia were also observed. Brain imaging revealed reductions in cortex, cerebellum and corpus callosum size with frequent white matter hyperintensity. Volumetric measurements indicated globally diminished volume rather than specific regional losses. We identified a reduced rate of trafficking into the Golgi apparatus and Golgi fragmentation in patient-derived fibroblasts that was rescued by wild-type TRAPPC6B. Molecular studies revealed a weakened interaction between mutant TRAPPC6B (c.454C>T, p.Q152*) and its TRAPP binding partner TRAPPC3. Patient-derived fibroblasts from the TRAPPC6B (c.454C>T, p.Q152*) variant displayed reduced levels of TRAPPC6B as well as other TRAPP II complex-specific members (TRAPPC9 and TRAPPC10). Interestingly, the levels of the TRAPPC6B homologue TRAPPC6A were found to be elevated. Moreover, co-immunoprecipitation experiments showed that TRAPPC6A co-precipitates equally with TRAPP II and TRAPP III, while TRAPPC6B co-precipitates significantly more with TRAPP II, suggesting enrichment of the protein in the TRAPP II complex. This implies that variants in TRAPPC6B may preferentially affect TRAPP II functions compared to TRAPP III functions. Finally, we assessed phenotypes in a Drosophila TRAPPC6B-deficiency model. Neuronal TRAPPC6B knockdown impaired locomotion and led to wing posture defects, supporting a role for TRAPPC6B in neuromotor function. Our findings confirm the association of damaging biallelic TRAPPC6B variants with microcephaly, intellectual disability, language impairments, and epilepsy. A subset of patients also exhibited dystonia and/or spasticity with impaired ambulation. These features overlap with disorders arising from pathogenic variants in other TRAPP subunits, particularly components of the TRAPP II complex. These findings suggest that TRAPPC6B is essential for brain development and function, and TRAPP II complex activity may be particularly relevant for mediating this function.

Biallelic MED27 variants lead to variable ponto-cerebello-lental degeneration with movement disorders

MED27 is a subunit of the Mediator multiprotein complex, which is involved in transcriptional regulation. Biallelic MED27 variants have recently been suggested to be responsible for an autosomal recessive neurodevelopmental disorder with spasticity, cataracts and cerebellar hypoplasia. We further delineate the clinical phenotype of MED27-related disease by characterizing the clinical and radiological features of 57 affected individuals from 30 unrelated families with biallelic MED27 variants. Using exome sequencing and extensive international genetic data sharing, 39 unpublished affected individuals from 18 independent families with biallelic missense variants in MED27 have been identified (29 females, mean age at last follow-up 17 ± 12.4 years, range 0.1-45). Follow-up and hitherto unreported clinical features were obtained from the published 12 families. Brain MRI scans from 34 cases were reviewed. MED27-related disease manifests as a broad phenotypic continuum ranging from developmental and epileptic-dyskinetic encephalopathy to variable neurodevelopmental disorder with movement abnormalities. It is characterized by mild to profound global developmental delay/intellectual disability (100%), bilateral cataracts (89%), infantile hypotonia (74%), microcephaly (62%), gait ataxia (63%), dystonia (61%), variably combined with epilepsy (50%), limb spasticity (51%), facial dysmorphism (38%) and death before reaching adulthood (16%). Brain MRI revealed cerebellar atrophy (100%), white matter volume loss (76.4%), pontine hypoplasia (47.2%) and basal ganglia atrophy with signal alterations (44.4%). Previously unreported 39 affected individuals had seven homozygous pathogenic missense MED27 variants, five of which were recurrent. An emerging genotype-phenotype correlation was observed. This study provides a comprehensive clinical-radiological description of MED27-related disease, establishes genotype-phenotype and clinical-radiological correlations and suggests a differential diagnosis with syndromes of cerebello-lental neurodegeneration and other subtypes of 'neuro-MEDopathies'.

Lunapark deficiency leads to an autosomal recessive neurodevelopmental phenotype with a degenerative course, epilepsy and distinct brain anomalies

LNPK encodes a conserved membrane protein that stabilizes the junctions of the tubular endoplasmic reticulum network playing crucial roles in diverse biological functions. Recently, homozygous variants in LNPK were shown to cause a neurodevelopmental disorder (OMIM#618090) in four patients displaying developmental delay, epilepsy and nonspecific brain malformations including corpus callosum hypoplasia and variable impairment of cerebellum. We sought to delineate the molecular and phenotypic spectrum of LNPK-related disorder. Exome or genome sequencing was carried out in 11 families. Thorough clinical and neuroradiological evaluation was performed for all the affected individuals, including review of previously reported patients. We identified 12 distinct homozygous loss-of-function variants in 16 individuals presenting with moderate to profound developmental delay, cognitive impairment, regression, refractory epilepsy and a recognizable neuroimaging pattern consisting of corpus callosum hypoplasia and signal alterations of the forceps minor ('ear-of-the-lynx' sign), variably associated with substantia nigra signal alterations, mild brain atrophy, short midbrain and cerebellar hypoplasia/atrophy. In summary, we define the core phenotype of LNPK-related disorder and expand the list of neurological disorders presenting with the 'ear-of-the-lynx' sign suggesting a possible common underlying mechanism related to endoplasmic reticulum-phagy dysfunction.

A Second Family with Myhre Syndrome Caused by the Same Recurrent SMAD4 Pathogenic Variation (p.Arg496Cys)

Introduction

Myhre syndrome (MS; OMIM #139210) is a rare connective tissue disorder presenting with cardiovascular, respiratory, gastrointestinal, and skeletal system findings. Fewer than 100 patients were reported until recently, and all molecularly confirmed cases had de novo heterozygous gain-of-function mutations in the SMAD4 gene. Dysregulation of the TGF-beta signaling pathway leads to axial and appendicular skeleton, connective tissue, cardiovascular system, and central nervous system abnormalities.

Case Presentation

Two siblings, 12 and 9 years old, were referred to us because of intellectual disability, neurodevelopmental delay, and dysmorphic facial features. Physical examination revealed hypertelorism, strabismus, small mouth, prognathism, short neck, stiff skin, and brachydactyly.

Discussion

With a clinical diagnosis of MS, the SMAD4 gene was analyzed via Sanger sequencing, and a heterozygous c.1486C>T (p.Arg496Cys) pathogenic variation was detected in both of the siblings. The segregation analysis revealed that the mutation was inherited from the father who displayed a milder phenotype. Among the 90 patients in the literature, one family was reported in which two siblings carried the same variation (p.Arg496Cys), inherited from the severely affected mother. We are reporting the second family which has three affected family members, a father and two children. We report this study to remind the clinicians to be aware of the parental transmission of SMAD4 variations and also evaluate the parents of the Myhre cases.

A Novel Mutation in the TRIP11 Gene: Diagnostic Approach from Relatively Common Skeletal Dysplasias to an Extremely Rare Odontochondrodysplasia

Odontochondrodysplasia (ODCD, OMIM #184260) is a rare, non-lethal skeletal dysplasia characterized by involvement of the spine and metaphyseal regions of the long bones, pulmonary hypoplasia, short stature, joint hypermobility, and dentinogenesis imperfecta. ODCD is inherited in an autosomal recessive fashion with an unknown frequency caused by mutations of the thyroid hormone receptor interactor 11 gene (TRIP11; OMIM *604505). The TRIP11 gene encodes the Golgi microtubule-associated protein 210 (GMAP-210), which is an indispensable protein for the function of the Golgi apparatus. Mutations in TRIP11 also cause achondrogenesis type 1A (ACG1A). Null mutations of TRIP11 lead to ACG1A, also known as a lethal skeletal dysplasia, while hypomorphic mutations cause ODCD. Here we report a male child diagnosed as ODCD with a novel compound heterozygous mutation who presented with skeletal changes, short stature, dentinogenesis imperfecta, and facial dysmorphism resembling achondroplasia and hypochondroplasia.

A homozygous Y443C variant in the RNPC3 is associated with severe syndromic congenital hypopituitarism and diffuse brain atrophy

Biallelic RNPC3 variants have been reported in a few patients with growth hormone deficiency, either in isolation or in association with central hypothyroidism, congenital cataract, neuropathy, developmental delay/intellectual disability, hypogonadism, and pituitary hypoplasia. To describe a new patient with syndromic congenital hypopituitarism and diffuse brain atrophy due to RNPC3 mutations and to compare her clinical and molecular characteristics and pituitary functions with previously published patients. A 20-year-old female presented with severe growth, neuromotor, and developmental delay. Her weight, height, and head circumference were 5135 gr (-25.81 SDS), 68 cm (-16.17 SDS), and 34 cm (-17.03 SDS), respectively. She was prepubertal, and had dysmorphic facies, contractures, and spasticity in the extremities, and severe truncal hypotonia. There were no radiological signs of a skeletal dysplasia. The bone age was extremely delayed at 2 years. Investigation of pituitary function revealed growth hormone, prolactin, and thyroid-stimulating hormone deficiencies. Whole-exome sequencing revealed a novel homozygous missense (c.1328A > G; Y443C) variant in RNPC3. Cranial MRI revealed a hypoplastic anterior pituitary with diffuse cerebral and cerebellar atrophy. The Y443C variant in RNPC3 associated with syndromic congenital hypopituitarism and abnormal brain development. This report extends the RNPC3-related hypopituitarism phenotype with a severe neurodegenerative presentation.

Osteogenesis imperfecta in 140 Turkish families: Molecular spectrum and, comparison of long-term clinical outcome of those with COL1A1/A2 and biallelic variants

BACKGROUND

Osteogenesis imperfecta (OI) is a clinically and genetically heterogeneous group of diseases characterized by increased bone fragility and deformities. Although most patients with OI have heterozygous mutations in COL1A1 or COL1A2, 17 genes have been reported to cause OI, most of which are autosomal recessive (AR) inherited, during the last years. The aim of this study is to determine the mutation spectrum in Turkish OI cohort and to investigate the genotype-phenotype correlation.

METHODS

150 patients from 140 Turkish families with OI phenotype were included in this study. Mutations in OI-related genes were identified using targeted gene panel, MLPA analysis for COL1A1 and whole exome sequencing. 113 patients who had OI disease-causing variants were followed for 1-20 years.

RESULTS

OI disease-causing variants were detected in 117 families, of which 62.4% in COL1A1/A2, 35.9% in AR-related genes. A heterozygous variant in IFITM5 and a hemizygous in MBTPS2 were also described, one in each patient. Eighteen biallelic variants (13 novel) were identified in nine genes (FKBP10, P3H1, SERPINF1, TMEM38B, WNT1, BMP1, CRTAP, FAM46A, MESD) among which FKBP10, P3H1 and SERPINF1 were most common. The most severe phenotypes were in patients with FKBP10, SERPINF1, CRTAP, FAM46A and MESD variants. P3H1 patients had moderate, while BMP1 had the mild phenotype. Clinical phenotypes were variable in patients with WNT1 and TMEM38B mutations. We also found mutations in ten genes (PLS3, LRP5, ANO5, SLC34A1, EFEMP2, PRDM5, GORAB, OCRL1, TNFRSF11B, DPH1) associated with diseases presenting clinical features which overlap OI, in eleven families.

CONCLUSION

We identified disease-causing mutations in 83.6% in a large Turkish pediatric OI cohort. 40 novel variants were described. Clinical features and long-term follow-up findings of AR inherited OI types and especially very rare biallelic variants were presented for the first time. Unlike previously reported studies, the mutations that we found in P3H1 were all missense, causing a moderate phenotype.

Expanding the clinical phenotype of RASopathies in 38 Turkish patients, including the rare LZTR1, RAF1, RIT1 variants, and large deletion in NF1

RASopathies are a group of disorders caused by pathogenic variants in the genes encoding Ras/mitogen-activated protein kinase pathway and share overlapping clinical and molecular features. This study is aimed to describe the clinical and molecular features of 38 patients with RASopathies. Sanger or targeted next-generation sequencing of related genes and multiplex ligation-dependent-probe amplification analysis for NF1 were performed. The pathogenic variant detection rate was 94.4%. While PTPN11 was responsible for 50% of 18 patients with Noonan syndrome (NS), SOS1, LZTR1, RIT1, and RAF1 were responsible for the remaining 27.8%, 11.1%, 5.5%, and 5.5%, respectively. Three variants in LZTR1 were novel, of which two were identified in the compound heterozygous state in a patient with intellectual disability and hypertrophic cardiomyopathy, whereas the third variant was found in the heterozygous state in a patient with pulmonary stenosis and normal intelligence. We described pyloric stenosis, knee dislocation, and cleft palate in patients with SOS1, RIT1, and RAF1 variants, respectively, that was not previously reported. We detected a PTPN11 variant in three patients from same family with NS with multiple lentigines. BRAF and MAP2K2 variants were found in eight patients with Cardiofaciocutaneous syndrome. Two variants in HRAS were detected in two Costello syndrome patients, one with a mild and the other with a severe phenotype. While large NF1 deletions were identified in four Neurofibromatosis-NS patients with intellectual disability, intelligence was normal in one patient with missense variant. In conclusion, this study provided three novel variants in LZTR1 and expanded the clinical phenotype of rare RASopathies.

A Novel Mutation of HINT1 Gene in an Adolescent Female with Axonal Neuropathy and Neuromyotonia

HINT1 gene mutations cause an axonal neuropathy with some specific findings including presence of neuromyotonia, autosomal recessive inheritance, onset in the first decade, and primary motor involvement. In this case report, we described an 18-year-old female patient who presented to the clinic with gait instability and muscle stiffness. A homozygous novel c.180_181delAT (p.Ser61Profs*8) variant in the HINT1 gene was found by clinical exome analysis. Parents were heterozygous for the same variant. The patient was diagnosed with autosomal recessive axonal neuropathy with neuromyotonia. The presence of neuromyotonia must be evaluated in patients with hereditary axonal neuropathies as this can help the diagnosis prior to genetic testing.

Cause of recurrent rhabdomyolysis, carnitine palmitoyltransferase II deficiency and novel pathogenic mutation

Carnitine palmitoyltransferase II (CPT II) deficiency is an autosomal inherited metabolic disorder in which the β-oxidation of the long chain fatty acids is defective. The clinical presentation may be in various forms; it presents itself in the severe form during neonatal and infantile periods and as the less severe myopathic form in the school age and adolescence. While the severity of the rhabdomyolysis attacks varies, occasionally the clinical course may be complicated with acute renal failure. Acylcarnitine analysis may help in the diagnosis of CPT II, but its normality does not indicate the absence of the disease. If there is strong suspicion, genetic analysis should be performed on the cases. In this article, we present a 15-year-old male patient who had two rhabdomyolysis attacks triggered by infection and starvation. Acylcarnitine analysis of the case was normal, CPT II deficiency was considered when the history was evaluated, and CPT II gene c.137A>G (p.Gln46Arg) homozygous novel pathogenic mutation was detected. CPT II deficiency is one of the most common causes of metabolic rhabdomyolysis in patients with recurrent episodes of rhabdomyolysis.

Neurofibromatosis type 1: Expanded variant spectrum with multiplex ligation-dependent probe amplification and genotype-phenotype correlation in 138 Turkish patients

OBJECTIVE

To investigate the variant spectrum and genotype-phenotype correlations in a Turkish cohort with Neurofibromatosis Type-1 (NF1).

MATERIALS AND METHODS

 We retrospectively investigated the clinical and molecular data of 138 NF1 patients from 129 families who had been followed-up for a median of 3.9 (1.25-18.5) years.

RESULTS

NF1 sequencing revealed 73 different intragenic variants, 19 of which were novel. Seven large deletions were detected by multiplex ligation-dependent probe amplification (MLPA) analyses. The total detection rate of pathogenic NF1 variants was found to be 87.1%. Comparing age groups, cutaneous neurofibromas, freckling, and Lisch nodules were more prevalent in patients older than 12 years (p > .05). Optic glioma detected in 17.3% of the patients and was significantly more common before the age of 6 (p > .001). Other solid tumors developed in 5% of the patients. There was no genotype-phenotype correlation between patients with truncating and nontruncating variants. However, six out of seven patients with large deletions had significant developmental delay, one patient with the c.2970_2972delAAT (p.Met992del) variant had only typical pigmentary features, and another patient with the c.4267A > G (p.Lys1423Glu) variant had CALMs, freckling, neurofibromas, and Noonan-like phenotype.

CONCLUSIONS

We described 19 novel variants and seven large deletions in NF1. Applying MLPA assay in NF1 is useful in expanding the molecular diagnosis. Although very limited genotype-phenotype correlation has been reported in NF1, the fact that specific phenotypic findings were observed in our patients with large deletions and two intragenic variants supports the studies published recently.

Investigation of (epi)genotype causes and follow-up manifestations in the patients with classical and atypical phenotype of Beckwith-Wiedemann spectrum

Beckwith-Wiedemann syndrome (BWS) is a genomic imprinting disorder, characterized by macroglossia, abdominal wall defects, lateralized overgrowth, and predisposition to embryonal tumors. It is caused by the defect of imprinted genes on chromosome 11p15.5, regulated by imprinting control (IC) domains, IC1, and IC2. Rarely, CDKN1C and chromosomal changes can be detected. The aim of this study is to retrospectively evaluate 55 patients with BWS using the new diagnostic criteria developed by the BWS consensus, and to investigate (epi)genetic changes and follow-up findings in classic and atypical phenotypes. Loss of methylation in IC2 region (IC2-LoM), 11p15.5 paternal uniparental disomy (pUPD11), and methylation gain in IC1 region (IC1-GoM) are detected in 31, eight, and five patients, respectively. Eleven patients have had no molecular defects. Thirty-five patients are classified as classical and 20 as atypical phenotype. Patients with classical phenotype are more frequent in the IC2-LoM (25/31), while patients with atypical phenotype are common in the pUPD11 group (5/8). Malignant tumors have developed in six patients (10.9%); three of these patients have IC1-GoM, two pUPD11, one IC2-LoM genotype, and four an atypical phenotype. We observed that the face was round in the infantile period and elongated as the child grew-up, developing prognathism and becoming asymmetrical if hemi-macroglossia was present in the classical phenotype. These findings were mild in the atypical phenotype. These results support the importance of using the new diagnostic criteria to facilitate the diagnosis of patients with atypical phenotype who have higher tumors risk. This study also provides important information about facial gestalt.

A Rare Cause of Adrenal Insufficiency - Isolated ACTH Deficiency Due to TBX19 Mutation: Long-Term Follow-Up of Two Cases and Review of the Literature

INTRODUCTION

Isolated adrenocorticotropic hormone (ACTH) deficiency (IAD) is a rare cause of adrenal insufficiency and T-box pituitary restricted transcription factor (TBX19) mutations are responsible for two-thirds of the neonatal onset form of the disease. IAD presents with hypoglycemia and prolonged jaundice in the neonatal period. TBX19 is important for both pro-opiomelanocortin (POMC) gene transcription and differentiation of POMC-expressing cells. We describe 2 patients, 1 with a reported and 1 with a novel TBX19 mutation, and present information about the long-term follow-up of these patients.

CASE PRESENTATION

Both patients had critical illnesses, recurrent hypoglycemia, convulsions, and neonatal hyperbilirubinemia. They also had low cortisol and ACTH levels, while other pituitary hormones were within the normal range. Pituitary imaging was normal. After hydrocortisone treatment, there was resolution of the hypoglycemia and the convulsions were controlled. Genetic studies of the patients revealed both had inherited a homozygous mutation of the TBX19 gene. The first patient had an alteration of NM_005149.3:c.856C>T (p.R286*) and the second patient had a novel NM_005149.3:c.584C>T (p.T195I) mutation, analyzed by next-generation sequencing. The noteworthy findings of the patients at follow-up were: short stature, microcephaly, and decreased pubic hair in the first, and dysmorphic features, Chiari type 1 malformation, tall stature, and low bone mineral density (BMD) in the second.

CONCLUSION

Congenital IAD can be life-threatening if it is not recognized and treated early. TBX19 mutations should be considered in the differential diagnosis of IAD. Further cases or functional analyses are needed for genotype-phenotype correlations. Low BMD, dysmorphic features, Chiari type 1 malformation, and sparse pubic hair are some of the important features in these patients.

A case with Rubinstein-Taybi syndrome: A novel frameshift mutation in the CREBBP gene

Rubinstein-Taybi syndrome (RSTS) is a developmental disorder characterized by a wide spectrum of multiple congenital anomalies and cognitive impairment. RSTS is primarily due to mutations in CREBBP (approximately 55% of cases) or EP300 (approximately 8% of cases) genes. A 2 month-old boy had atypical facial findings such as low anterior hairline, triangular face, hirsutism on forehead, down-slanting palpebral fissures, beaked nose, broad nasal bridge, triangular mouth and pointed chin and skeletal finding including broad great thumbs and halluces, and accessory nipple. With this paper, we reported a novel frameshift mutation which is led to premature stop codon in CREBBP gene. As a result, c.2057dupC, reported in this paper enlarges the molecular spectrum of disease-causing CREBBP gene.

MAB21L1 loss of function causes a syndromic neurodevelopmental disorder with distinctive cerebellar, ocular, craniofacial and genital features (COFG syndrome)

BACKGROUND

Putative nucleotidyltransferase MAB21L1 is a member of an evolutionarily well-conserved family of the male abnormal 21 (MAB21)-like proteins. Little is known about the biochemical function of the protein; however, prior studies have shown essential roles for several aspects of embryonic development including the eye, midbrain, neural tube and reproductive organs.

OBJECTIVE

A homozygous truncating variant in MAB21L1 has recently been described in a male affected by intellectual disability, scrotal agenesis, ophthalmological anomalies, cerebellar hypoplasia and facial dysmorphism. We employed a combination of exome sequencing and homozygosity mapping to identify the underlying genetic cause in subjects with similar phenotypic features descending from five unrelated consanguineous families.

RESULTS

We identified four homozygous MAB21L1 loss of function variants (p.Glu281fs*20, p.Arg287Glufs*14 p.Tyr280* and p.Ser93Serfs*48) and one missense variant (p.Gln233Pro) in 10 affected individuals from 5 consanguineous families with a distinctive autosomal recessive neurodevelopmental syndrome. Cardinal features of this syndrome include a characteristic facial gestalt, corneal dystrophy, hairy nipples, underdeveloped labioscrotal folds and scrotum/scrotal agenesis as well as cerebellar hypoplasia with ataxia and variable microcephaly.

CONCLUSION

This report defines an ultrarare but clinically recognisable Cerebello-Oculo-Facio-Genital syndrome associated with recessive MAB21L1 variants. Additionally, our findings further support the critical role of MAB21L1 in cerebellum, lens, genitalia and as craniofacial morphogenesis.

Vanishing white matter disease with a novel EIF2B5 mutation: A 10-year follow-up

BACKGROUND

Vanishing white matter disease is a heterogeneous disorder caused by mutation in one of the five genes encoding subunits of the eukaryotic initiation factor eIF2B. It is a heterogeneous disorder due to phenotypic variation and a clear genotype-phenotype correlation could not be established so far. We describe a novel mutation in the EIF2B5 gene by analyzing the clinical phenotype and the progression of brain lesions for 10 years.

CASE

A novel mutation in the EIF2B5 gene was detected in the heterozygous state; c.1688G > A (p. Arg563Gln) mutation in exon 12, accompanied by a previously detected c.806G > A (p. Arg269Gln) mutation in exon 6, leading to substitution of arginine for a glutamine. This compound heterozygous mutation was associated with disease onset at early childhood and relatively slow progression of neurological deterioration. In contrast to previous findings indicated the association of c.806G > A mutation and peripheral neuropathy in patients with vanishing white matter disease, electromyography of our case was normal. The corpus callosum inner rim was the affected area at early stages, which may be remarkable for early diagnosis of vanishing white matter disease. Serial follow-up magnetic resonance imaging revealed the white matter signal abnormality, subsequently cystic degeneration and decrease in white matter volume.

CONCLUSION

The novel mutation c.1688G > A in compound heterozygous state leads to intermediate phenotype of the vanishing white matter disease. In the early stages of the disease the signal abnormality in the corpus callosum inner rim might be remarkable.

Longitudinal Follow-Up of Two Patients with Dysspondyloenchondromatosis due to Novel Heterozygous Mutations in COL2A1

Dysspondyloenchondromatosis (DSC) is a rare form of generalized enchondromatosis and characterized by short stature with unequal limb length, multiple enchondromas in metaphyseal and diaphyseal parts of the long tubular bones, and progressive kyphoscoliosis. Although the COL2A1 gene mutation was found to be responsible for DSC, a case of DSC with no pathogenic mutation in the COL2A1 gene has also been reported, suggesting that the condition is genetically heterogeneous. Here, we report 2 novel heterozygous mutations in COL2A1 in 2 patients with DSC. They had prenatal onset short stature with unequal limb length and generalized enchondroma-like lesions in metaphyseal and diaphyseal parts of the long tubular bones, and osteopenia. The first patient was diagnosed at 3 months of age and followed for 10.5 years. Severe lumbosacral scoliosis and recurrent fractures were observed. The second patient was diagnosed at the age of 4 years. Mild deterioration in scoliosis was observed during the 3-year-long follow-up period. However, skeletal radiography of both patients showed the improvement of enchondromatous lesions. In conclusion, we verified that the COL2A1 gene mutations are responsible for the DSC phenotype. We observed severe osteopenia and fractures which were not reported previously.

Expanding the Phenotype of Homozygous KCNMA1 Mutations; Dyskinesia, Epilepsy, Intellectual Disability, Cerebellar and Corticospinal Tract Atrophy

Background:

The KCNMA1 gene encodes the α-subunit of the large conductance, voltage, and calcium-sensitive potassium channel (BK channels) that plays a critical role in neuronal excitability. Heterozygous mutations in KCNMA1 were first illustrated in a large family with generalized epilepsy and paroxysmal nonkinesigenic dyskinesia. Recent research has established homozygous KCNMA1 mutations accountable for the phenotype of cerebellar atrophy, developmental delay, and seizures.

Case Report:

Here, we report the case of a patient with a novel homozygous truncating mutation in KCNMA1 (p.Arg458Ter) presenting with both the loss- and gain-of-function phenotype with paroxysmal dyskinesia, epilepsy, intellectual delay, and corticospinal–cerebellar tract atrophy.

Conclusion:

This report extends the KNCMA1 mutation phenotype with a patient who carries a novel frameshift variant, presenting with both the gain- and loss-of-function phenotypes along with spinal tract involvement as a novel characteristic.

Hereditary spastic paraplegia type 35 caused by a novel FA2H mutation

Bektaş G, Yeşil G, Yıldız EP, Aydınlı N, Çalışkan M, Özmen M. Hereditary spastic paraplegia type 35 caused by a novel FA2H mutation. Turk J Pediatr 2017; 59: 329-334. Hereditary spastic paraplegia type 35 (SPG35) is a rare disorder characterized by progressive spasticity. Mutations in the fatty acid 2-hydroxylase (FA2H) gene in different loci are responsible for phenotypic variability. We aimed to define the phenotype of SPG35 linked to a novel homozygous mutation c.160_169dup (p.Asp57Glyfs*48) in the FA2H gene, and compared with the clinical characteristics and neuroimaging findings of the patients with mutation in the FA2H gene. We describe a 5-year-old boy presenting with spastic paraplegia. He developed a rapid progressive spastic paraplegia and loss of ambulation at an early age, despite the absence of accompanying seizure, neuropathy, cognitive impairment, speech disturbance, and optic atrophy. Neuroimaging revealed white matter changes without brain iron accumulation. A duplication variation; leading to a truncated protein c.160_169dup in the FA2H gene was found on the homozygous state. A homozygous mutation c.160_169dup in the FA2H gene, which resulted in SPG35 phenotype, may present with rapid progressive spastic paraplegia at an early age.

Mucolipidosis type III gamma: Three novel mutation and genotype-phenotype study in eleven patients

Mucolipidosis type III gamma (MLIII gamma) is a lysosomal storage disease characterized by joint stiffness, mild coarse face and corneal clouding, which becomes recognizable usually in childhood. Biallelic mutations in the GNPTG gene, which encode the γ subunit of the N-acetylglucosamine-1-phosphotransferase enzyme, are the underlying cause of MLIII gamma. The aim of this study is to evaluate the longitudinal findings and genotype of eleven patients from eight families with MLIII gamma and to establish a genotype-phenotype correlation. The most frequently observed initial finding was stiffness of finger joints, which detected in patients between 18month-olds and five year-olds. However, in four patients presented here, initial finding was knee pain or waddling gait, which started between six-16years of age. All patients also had variable degrees of stiffness on large joints. The longest follow up period was 16years while the shortest was three years and six months. We observed that the patients who had an early onset disease and severe joint stiffness had also rapidly progressive joint involvement mostly localized in hands, shoulders, and hip. However; the patients with late onset and/or mild joint stiffness experienced slowly progressive symptoms. Most patients dropped in their growth curve in time and the ones who were severely affected reached the final height below the third centile. Seven disease-causing mutations, three of them novel, were detected in GNPTG gene. According to our clinical observations c.493_494insC and c.283_284insC mutations lead to a severe phenotype and c.196C>T, c.347_349del, c.652_655delTACT and c.445delG/c.367A>G mutations seemed to generate a milder phenotype.

Endocrinological Evaluations of a Neurofibromatosis Type 1 Cohort: Is it Necessary to Evaluate Autoimmune Thyroiditis in Neurofibromatosis Type 1?

Background:

Neurofibromatosis type 1 is an autosomal dominant neurocutaneous disorder in which the coexistence of autoimmune thyroiditis and thyroid gland tumours has been reported previously.

Aims:

To determine the thyroid function and autoimmune thyroid diseases in neurofibromatosis type 1 patients in order to identify the possible association between neurofibromatosis type 1 and thyroid diseases.

Study Design:

Case-control study.

Methods:

The study includes 78 consecutive patients diagnosed with neurofibromatosis type 1 between June 2010 and June 2014 and 50 healthy controls. Baseline demographic data were generated from patient examination record forms, including age, sex, height, and weight, as well as levels of free triiodothyronine, free thyroxine, thyroid-stimulating hormone, anti-thyroid peroxidase and anti-thyroglobulin levels.

Results:

Mean age, sex, and body mass index were similar in both groups (p>0.05). The mean levels of free triiodothyronine, free thyroxine, and thyroid-stimulating hormone were not statistically different between the neurofibromatosis type 1 and control groups. Similarly, no statistically significant difference was observed between the neurofibromatosis type 1 and control groups for anti-thyroid peroxidase and anti-thyroglobulin positivity (2.5% vs 0%, p>0.05).

Conclusion:

Screening for autoimmune thyroid disease and thyroid function seems to be unnecessary in patients with neurofibromatosis type 1.

Stuve-Wiedemann syndrome: is it underrecognized?

Stuve-Wiedemann Syndrome (SWS) (OMIM #601559) is an autosomal recessive disorder characterized by skeletal changes, bowing of the lower limb, severe osteoporosis and joint contractures, episodic hyperthermia, frequent respiratory infections, feeding problems and high mortality in early life. It is caused by mutation in the leukemia inhibitory factor receptor gene (LIFR; 151443) on chromosome 5p13. We provide the clinical follow-up and molecular aspects of six new patients who carried the same novel mutation in the LIFR gene (p.Arg692X) and three patients carried a common haplotype at the LIFR locus supporting a founder effect in the Turkish population. The probable pathogenesis of the features is also discussed. Osseous findings in the presence of other above-mentioned morbid conditions should raise the suspicion of SWS in neonates especially in Arabic and Eastern Mediterranean countries with high rate of consanguineous marriages like in Turkey. Severe osteoporosis, bone deformities, milias, leukocoria, inflammatory lesions on distal extremities, tongue biting behavior and oral ulcers could be more prominent features of the survivors beyond the neonatal period while respiratory and feeding problems are remitting. It is of crucial importance to diagnose such babies earlier in order to prevent extensive laboratory workup and to provide proper genetic counseling.

A giant ovarian cyst in a neonate with classical 21-hydroxylase deficiency with very high testosterone levels demonstrating a high-dose hook effect

Congenital adrenal hyperplasia (CAH) is a group of disorders affecting the adrenal steroid synthesis. The most common form, 21-hydroxylase deficiency (21-OHD), leads to decreased production of cortisol and aldosterone with increased androgen secretion. In classic CAH, glucocorticoid treatment can be life-saving and serves to bring the symptoms under control. However, the treatment challenge is to effectively control the excess androgen effect by using the lowest possible glucocorticoid dose. Previous studies suggested a relationship between ovarian cyst formation and adrenal androgen excess, but neonatal large ovarian cysts have been very rarely reported in newborns with CAH. Here, we present the unique case of a neonate with classical 21-OHD who underwent surgery for a giant (10x8x7 cm) unilateral solitary ovarian follicular cyst on the 2nd postnatal day. Hormonal evaluation of the patient revealed high-dose hook effect for serum testosterone levels for the first time by a two-site immunoradiometric assay. Possible mechanisms by which androgen excess may cause ovarian cyst formation are discussed.

Thiamine-responsive megaloblastic anemia: early diagnosis may be effective in preventing deafness

Thiamine-responsive megaloblastic anemia syndrome is an autosomal recessive disorder characterized by diabetes mellitus, megaloblastic anemia and sensorineural hearing loss. Mutations in the SLC19A2 gene, encoding a high-affinity thiamine transporter protein, THTR-1, are responsible for the clinical features associated with thiamine-responsive megaloblastic anemia syndrome in which treatment with pharmacological doses of thiamine correct the megaloblastic anemia and diabetes mellitus. The anemia can recur when thiamine is withdrawn. Thiamine may be effective in preventing deafness if started before two months. Our patient was found homozygous for a mutation, 242insA, in the nucleic acid sequence of exon B, with insertion of an adenine introducing a stop codon at codon 52 in the high-affinity thiamine transporter gene, SLC19A2, on chromosome 1q23.3.

Facial dysmorphism in Leigh syndrome with SURF-1 mutation and COX deficiency

Leigh syndrome is an inherited, progressive neurodegenerative disorder of infancy and childhood. Mutations in the nuclear SURF-1 gene are specifically associated with cytochrome C oxidase-deficient Leigh syndrome. This report describes two patients with similar facial features. One of them was a 2(1/2)-year-old male, and the other was a 3-year-old male with a mutation in SURF-1 gene and facial dysmorphism including frontal bossing, brachycephaly, hypertrichosis, lateral displacement of inner canthi, esotropia, maxillary hypoplasia, hypertrophic gums, irregularly placed teeth, upturned nostril, low-set big ears, and retrognathi. The first patient's magnetic resonance imaging at 15 months of age indicated mild symmetric T2 prolongation involving the subthalamic nuclei. His second magnetic resonance imaging at 2 years old revealed a symmetric T2 prolongation involving the subthalamic nuclei, substantia nigra, and medulla lesions. In the second child, at the age of 2 the first magnetic resonance imaging documented heavy brainstem and subthalamic nuclei involvement. A second magnetic resonance imaging, performed when he was 3 years old, revealed diffuse involvement of the substantia nigra and hyperintense lesions of the central tegmental tract in addition to previous lesions. Facial dysmorphism and magnetic resonance imaging findings, observed in these cases, can be specific findings in Leigh syndrome patients with cytochrome C oxidase deficiency. SURF-1 gene mutations must be particularly reviewed in such patients.