Aarskog-Scott syndrome: a novel mutation in the FGD1 gene associated with severe craniofacial dysplasia

Aarskog syndrome (AAS) is an X-linked human disease that affects the skeletal formation and embryonic morphogenesis and is caused by mutations in the FGD1 gene. Patients typically show distinctive skeletal and genital developmental abnormalities, but a broad spectrum of clinical phenotypes has been observed. We report here on the clinical and molecular analysis of a family that reveals a novel FGD1 mutation in a 9-year-old boy displaying extreme craniofacial dysplasia associated with attention deficit hyperactivity disorder. Sequencing of FGD1 revealed a novel mutation in exon 7 at position c.1468 C > T in the index patient, leading to a stop codon in the highly conserved RhoGEF gene domain. His mother and maternal grandmother were also found to be heterozygous for this FGD1 mutation. Conclusion: Our results identify a novel mutation of FDG1 in a family with Aarskog syndrome and underscore the phenotypical variability of this condition.     

Dystroglycanopathy with two novel POMT1 mutations in a Chinese boy with developmental delay and muscular dystrophy

Alpha-dystroglycanopathies are a group of diseases due to reduced glycosylation of alpha-dystroglycan, which commonly result from mutations in POMT1, POMT2, and POMGnT1. Patients with alpha-dystroglycanopathies present with muscular, cerebral, and ocular involvements with differing severities. We reported a boy who presented with muscular dystrophy, developmental delay, and non-specific white matter lesions. Mutation analysis of POMT1 was performed and revealed two novel mutations, a substitution mutation (c.176T>G) and a duplication mutation (c.2059dupC) which results in premature termination of translation. In-silico prediction in five different platforms concurred that the substitution is damaging, and functional studies by immunofluorescence revealed lack of staining in the carbohydrate moiety of alpha-dystroglycan, confirming the molecular findings in a functional manner. In conclusion, we reported the first case of genetically confirmed alpha-dystroglycanopathy due to mutations in POMT1 in Chinese.     

Mutational analyses of UPIIIA, SHH, EFNB2 and HNF1beta in persistent cloaca and associated kidney malformations

Objectives‘Persistent cloaca’ is a severe malformation affecting females in which the urinary, genital and alimentary tracts share a single conduit. Previously, a Uroplakin IIIA (UPIIIA) mutation was reported in one individual with persistent cloaca, and UPIIIA, Sonic Hedgehog (SHH), Ephrin B2 (EFNB2) and Hepatocyte Nuclear Factor 1β (HNF1β) are expressed during the normal development of organs that are affected in this condition. HNF1β mutations have been associated with uterine malformations in humans, and mutations of genes homologous to human SHH or EFNB2 cause persistent cloaca in mice.Patients and methodsWe sought mutations of coding regions of UPIIIA, SHH, EFNB2 and HNF1β genes by direct sequencing in a group of 20 patients with persistent cloaca. Most had associated malformations of the upper renal tract and over half had impaired renal excretory function. The majority of patients had congenital anomalies outside the renal/genital tracts and two had the VACTERL association.ResultsApart from a previously described index case, we failed to find UPIIIA mutations, and no patient had a SHH, EFNB2 or HNF1β mutation.ConclusionPersistent cloaca is only rarely associated with UPIIIA mutation. Despite the fact that SHH and EFNB2 are appealing candidate genes, based on their expression patterns and mutant mice phenotypes, they were not mutated in these humans with persistent cloaca. Although HNF1β mutations can perturb paramesonephric duct fusion in humans, HNF1β was not mutated in persistent cloaca.     

Periventricular nodular heterotopia in patients with filamin-1 gene mutations: neuroimaging findings

Background. The filamin-1 (FLN-1) gene is responsible for periventricular nodular heterotopia (PNH), which is an X-linked dominant neuronal migration disorder. Objective. To review the clinical and imaging findings in a series of patients with documented filamin-1 mutations.¶Materials and methods. A retrospective review of the medical records and MR studies of a series of patients with PNH and confirmed FLN-1 mutations was done. There were 16 female patients (age range: .67–71 years; mean = 28.6) with filamin-1 gene mutations. ¶Results. In six of the patients the same mutation was inherited in four generations in one pedigree. In a second pedigree, a distinct mutation was found in two patients in two generations. In a third pedigree, a third mutation was found in four patients in two generations. The remaining four patients had sporadic de novo mutations that were not present in the parents. Ten patients had seizures, and all patients had normal intelligence. In all 16 patients MR demonstrated bilateral near-continuous PNH. There were no consistent radiographic or clinical differences between patients carrying different mutations.¶Conclusion. Patients with confirmed FLN-1 gene mutations are usually female and have a distinctive MR pattern of PNH. Other female patients with this same MR pattern probably harbor FLN-1 mutations and risk transmission to their progeny. This information is important for genetic counseling.     

Connexin 26 <Emphasis Type="Italic">(GJB2)</Emphasis> Mutations Associated with Non-Syndromic Hearing Loss (NSHL)

Objective

To determine the prevalence and spectrum of Connexin 26 (GJB2) mutations in pre-lingual non-syndromic hearing loss (NSHL) patients in authors’ centre and to review the data of Indian patients from the literature.

Methods

Sanger sequencing of entire coding region contained in single exon (Exon 2) of GJB2 gene in 15 patients of NSHL.

Results

GJB2 mutations were found in 40% (6/15) of NSHL patients, out of which mono-allelic were 33.3% (2/6). Bi-allelic GJB2 mutations were identified in 4 of 6 patients. Most common GJB2 mutation identified was c.71G?>?A(p.W24X), comprising 30% of the total GJB2 mutant alleles. Six studies involving 1119 patients with NSHL were reviewed and 4 of them have reported c.71G?>?A(p.W24X) as the commonest mutation while 2 studies found c.35delG as the commonest. GJB2 mutations accounted for 10.9%–36% cases of NSHL. Sixteen other mutations in GJB2 gene were reported in Indian patients out of which 6 mutations other than c.71G?>?A(p.W24X) viz., c.35delG, c.1A?>?G(p.M1V), c.127G?>?A(p.V43 M), c.204C?>?G(p.Y86X), c.231G?>?A(p.W77X) and c.439G?>?A(p.E147K) were identified in the present study.

Conclusions

Connexin 26 (GJB2) mutations are responsible for 19.4% of NSHL in Indian population. The c.71G?>?A(W24X) and c.35delG were the most prevalent GJB2 mutations accounting for 72.2% (234 of 324 total mutated alleles from 7 studies) and 15.4% (50 of 324 total mutated alleles from 7 studies) respectively. Thus, screening of these two common mutations in GJB2 gene by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) would greatly help in providing easy genetic diagnosis and help in genetic counseling of the families with NSHL.

     

PRRT2 mutation causes paroxysmal kinesigenic dyskinesia and hemiplegic migraine in monozygotic twins

PRRT2 gene mutations have recently been identified as a causative gene of Paroxysmal kinesigenic dyskinesia (PKD), a rare movement disorder characterised by the occurrence of chorea, dystonia or athetosis triggered by sudden action. Some patients have additional intermittent neurologic disorders like infantile convulsions. The association with migraine has been rarely reported in this condition. Here we report the coexistence of PKD and hemiplegic migraine in twins harbouring a heterozygous mutation in PRRT2.Two monozygotic twins manifesting PKD together with repeated episodes of migraine with some severe attacks of hemiplegic migraine have been followed and treated for more than 10 years.Molecular genetic analysis disclosed the c.649_650insC, p.R217Pfs*8 heterozygous mutation in both twins. This mutation was segregating from the mother who likewise harboured the same mutation c.649dupC although she had never manifested PKD but complained of rare common migraine attacks in her past history.The association of PKD and hemiplegic migraine has been previously reported in one large family, associated to febrile convulsions and afebrile seizures in some individuals, but our report relates this association of symptoms to a mutation in PRRT2. The co-occurrence of both hemiplegic migraine and PKD in monozygotic twins expands the phenotypic spectrum of intermittent manifestations related to PRRT2 and perhaps suggests an additional causing gene for hemiplegic migraine.     

GATA3 mutation in a family with hypoparathyroidism,deafness and renal dysplasia syndrome

Background

The hypoparathyroidism, deafness and renal dysplasia (HDR) syndrome is an autosomal dominant disorder primarily caused by GATA3 gene mutation. We report here a case that both of a Chinese boy and his father had HDR syndrome which caused by a novel mutation of GATA3.

Methods

Polymerase chain reaction and DNA sequencing was performed to detect the exons of the GATA3 gene for mutation analysis.

Results

Sequence analysis of GATA3 revealed a heterozygous nonsense mutation in this family: a mutation of GATA3 at exon 2 (c.515C >A) that resulted in a premature stop at codon 172 (p.S172X) with a loss of two zinc finger domains.

Conclusion

We identified a novel nonsense mutation which will expand the spectrum of HDR-associated GATA3 mutations.     

Germ-line mutation of KCNQ2, p.R213W, in a Japanese family with benign familial neonatal convulsion

Background: Benign familial neonatal convulsion (BFNC) is an autosomal‐dominantly inherited epilepsy of neonates. The KCNQ2 and KCNQ3 genes have been cloned as the responsible genes for BFNC. Detection of mutations in these genes is helpful for confirmation of BFNC or differential diagnosis of convulsive disorders in the neonatal period. Methods: A Japanese family with BFNC was investigated. Two siblings were clinically diagnosed as having BFNC. KCNQ2 and KCNQ3 were screened for mutations using a combination of polymerase chain reaction and denaturing high‐performance liquid chromatography. Nucleotide substitutions were confirmed by direct sequencing. Results: In the affected siblings a C‐to‐T heterozygous substitution was detected at nucleotide 683 (c.683C>T) in KCNQ2, leading to substitution of arginine with tryptophan at amino acid position 213 (p.R213W) in the S4 voltage‐sensing domain of the KCNQ2 protein. The detected mutation may disrupt this highly conserved region among potassium channel proteins. The c.683C>T substitution in KCNQ2 was not present in the parents. KCNQ3 was also analyzed and a single nucleotide polymorphism, c.1241A>G (National Center for Biotechnology Information (NCBI), SNP ID: rs2303995), was detected in the index family. Conclusions: Two siblings with BFNC had a novel heterozygous missense mutation, p.R213W, in KCNQ2. This mutation may affect potassium gating, leading to neuronal excitability or convulsions in the patients. Furthermore, neither of the parents had the p.R213W mutation, indicating that it was a germ‐line mutation. The possibility of recurrence of such a germ‐line mutation in the next siblings should be explained during genetic counseling.     

Identification of a novel variant of the RET proto-oncogene in a novel family with Hirschsprung’s disease

Purpose

Hirschsprung’s disease (HSCR) is a congenital disorder of the enteric nervous system characterized by the absence of ganglion cells in the Auerbach’s and Meissner’s plexuses. Although about 7% of cases are hereditary, the causal mutations have not been completely characterized. We encountered a novel family with inherited HSCR and screened them for causal mutations.

Methods

A Japanese family of five female patients and six unaffected individuals was subjected to a whole-exome analysis with a next-generation sequencer.

Results

After exome sequencing and the annotation of mutations, we identified co-segregated mutations with sequential filtering steps via a standard protocol. Eight mutations were identified: two on chromosome 10 and six on chromosome 11. We used pathogenicity prediction tools such as Genomic Evolutionary Rate Profiling, SIFT, and PolyPhen2 to predict the impact of mutations on the protein activity. S922Y, a novel mutation of RET, was identified as a likely causal mutation. In addition, a mutation of rs2435357T, known as enhancer of RET located in intron 1 of RET, was detected in this family.

Conclusion

The coexistence of RET mutations in both the exon (S922Y) and intron1 (rs2435357T) indicated a risk of HSCR in this family.

     

儿童心肌致密化不全6例临床表现及基因变异分析

该文总结分析儿童心肌致密化不全（NVM）的临床和基因变异特点。6例NVM患儿起病年龄3个月至12岁,男4例,女2例,心律失常5例,心功能不全3例,精神差1例,胸闷、叹气1例。4例患儿检测到NVM相关基因变异,其中MYH7基因变异2例,PRDM16基因变异1例,ACTN2基因+TNNT2基因变异1例。心功能改善4例;2例患儿心功能改善不明显,其发病年龄小,超声心动图示收缩功能降低更明显,心肌酶、氨基末端脑钠肽前体升高更明显。NVM是引起儿童慢性心力衰竭的重要原因之一,对于首发有胸闷、叹气、心律失常、心影增大、心肌酶增高明显的患儿,进行超声心动图、心脏磁共振检查,可确诊NVM,NVM可有多种基因变异。     

A novel mutation of 5α-steroid reductase 2 deficiency (CD 65 ALA-PRO) with severe virilization defect in a Turkish family and difficulty in gender assignment

Molecular genetic characterization of mutations in SRD5A2 gene is used as an essential procedure for the final diagnosis of 5α-reductase deficiency. Here, we report a novel homozygous point mutation of SRD5A2 gene at codon 65 in exon 1, due to a proline for alanine substitution in a Turkish family whose proband has severe undervirilization. This mutation has not been reported up to date in association with 5α-reductase deficiency in various ethnic groups. We discussed some questions about gender assignment in addition to the molecular and clinical characteristics of the disease.     

Congenital chloride diarrhea in Korean children: novel mutations and genetic characteristics

Congenital chloride diarrhea (CLD, OMIM#214700) is an autosomal recessive disorder caused by mutations in the solute carrier family 26 member 3 (SLC26A3) gene, which encodes an intestinal chloride/bicarbonate exchanger. While more than 50 mutations have been identified throughout the world, there have been no data on the genetic characteristics of the patients of East Asian ethnic origin. In this study, we performed genetic analysis by direct sequencing of the 20 exons and parts of exon–intron boundaries of the SLC26A3 gene in eight patients of Korean origin with non-consanguineous parents. We identified three novel mutations, including two splice-site mutations (c.2063-1G>T in intron 18, c.1047+3 A>C in intron 12) and one missense mutation (p.Ser134Asn in exon 5). One previously identified mutation was also found (p.Pro131Leu in exon 5). The most common mutation was c.2063-1G>T, which was found in at least one allele of all patients. Conclusion: This is the first report to demonstrate the genetic background of CLD in a single ethnic group of East Asian descent. The c.2063-1G>T mutation could be suggested as a founder mutation in Korean population so that the targeting sequencing for the mutation would be a cost-efficient screening method to confirm a diagnosis of CLD in patients of Korean descent.     

Protein C deficiency as the major cause of thrombophilias in childhood

Genetic predisposition of thromboembolism depends on the racial background. Factor V Leiden (G1691A) and factor II mutation (G20210A) are the leading causes of inherited thrombophilias in Caucasians, but are not found in Asian ancestries. Protein S (PS), protein C (PC) and antithrombin (AT) activity are reportedly low in 65% of adult Japanese patients with deep vein thrombosis. Approximately half of the patients with each deficiency carry the heterozygous mutation of PS (PROS1; 20%), PC (PROC; 10%), and AT genes (SERPINC1: 5%). Recently, several studies have revealed an outline of inherited thrombophilias in Japanese children. Congenital thrombophilias in 48 patients less than age 20 years consisted of 45% PC deficiency, 15% PS deficiency and 10% AT deficiency, along with other causes. All PS‐ and AT‐deficient patients had a heterozygous mutation of the respective gene. On the other hand, PC‐deficient patients were considered to carry the homozygous or compound heterozygous mutation in 50%, the heterozygous mutation in 25%, and unknown causes in the remaining 25% of patients. Half of unrelated patients with homozygous or compound heterozygous PROC mutations carried PC‐nagoya (1362delG), while their parents with its heterozygous mutation were asymptomatic. Most of the PC‐deficient patients developed intracranial lesion and/or purpura fulminans within 2 weeks after birth. Non‐inherited PC deficiency also conveyed thromboembolic events in early infancy. The molecular epidemiology of thrombosis in Asian children would provide a clue to establish the early intervention and optimal anticoagulant therapy in pediatric PC deficiency.     

Permanent neonatal diabetes in siblings with novel C109Y INS mutation transmitted by an unaffected parent with somatic mosaicism

Mutations involving the insulin (INS) gene are a common cause of permanent neonatal diabetes (PND). Although INS mutations typically occur de novo and germline INS mutations transmitted to offspring by unaffected parents has been described, somatic mosaicism in a parent with an INS mutation has not been previously reported. We describe two siblings (one brother and one sister) with PND (26‐ and 19‐yr old diagnosed at 3 and 7 months old, respectively), whose parents were unaffected. We performed genetic analysis of leukocyte DNA for this family. Both patients were found to carry the novel heterozygous c.326G>A substitution in exon 3 of INS, resulting in a p.C109Y change of the insulin protein. Analyses of leukocyte DNA from the parents revealed low level mutation in the sequencing trace of the father, raising the possibility of somatic mosaicism. Real‐time polymerase chain reaction (PCR) analysis showed he had approximately 73% of the mutant allele relative to his affected son. This first report of somatic mosaicism in an unaffected parent with an INS mutation suggests that parental mosaicism may be responsible for the transmission of PND in patients with de novo INS mutations. As such, appropriate counseling for recurrent risks should be considered and we recommend that molecular genetic testing for future siblings at birth should be offered to the parents of children with INS mutation.     

Alternating hemiplegia of childhood in Denmark: Clinical manifestations and ATP1A3 mutation status

Alternating hemiplegia of childhood (AHC) is a rare neurodevelopmental disorder characterized by early-onset recurrent distinctive hemiplegic episodes commonly accompanied by other paroxysmal features and developmental impairment. De novo mutations in ATP1A3 were recently identified as a genetic cause of AHC. To describe the entire Danish cohort of paediatric AHC patients we approached neuropaediatricians nationwide. All currently acknowledged Danish patients ≤16 years with AHC were genetically tested and seen by the same child neurologist (PU). Ten patients; seven girls and three boys were identified. Mean present age was 10.0 years (range 1–16). Mean age at presentation was 7.4 months (range 1–18 months). Sequencing of ATP1A3 in all ten patients revealed a pathogenic mutation in seven. Two females with moderate psychomotor impairment were heterozygous for the known p.G947R mutation, whereas one severely retarded boy was heterozygous for the common p.E815K mutation. The prevalent p.D801N mutation was identified in two moderate to severely retarded children. Interestingly, in a set of monochorionic male twins a novel p.D801E mutation was identified, underscoring that the asparagine at position 801 is a mutation hotspot. Three girls aged 5–13 years did not reveal any ATP1A3 mutations. They were rather mildly clinically affected and displayed a normal or near-normal psychomotor development. This is the first study of AHC in the Danish paediatric population. The patients harboured a wide range of psychomotor difficulties. Patients with no mutation detected tended to be less severely affected. Prevalence was approximately 1 per 100,000 children.     

Familial hypomagnesemia with hypercalciuria and nephrocalcinosis in three siblings having the same genetic lesion but different clinical presentations

Background

This article summarizes the varying clinical manifestations of three siblings with familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) caused by the same genetic lesion.

Methods

The medical records of three siblings with FHHNC (one girl and two boys, aged 6 to 12 years) were reviewed and the clinical manifestations and treatment of their disease were described.

Results

Despite varying phenotypes, each sibling had the same genetic lesion??a novel homozygous mutation in CLDN16 (c.211A>G, M71V).

Conclusion

Although FHHNC is a rare disorder, this report is significant for the following reasons: (i) it describes a novel CLDN16 mutation causing FHHNC, adding to the literature of FHHNC-causing CLDN16 mutations; (ii) it suggests that genes other than CLDN16 or epigenetic factors are involved in the clinical spectrum of FHHNC; and (iii) it reinforces the variability of disease manifestation and genotype-phenotype correlations.     

A novel mutation of anti-Mullerian hormone gene in Persistent Mullerian Duct Syndrome presented with bilateral cryptorchidism: A case report

BackgroundWe report a novel mutation in a case of Persistent Mullerian Duct Syndrome (PMDS). PMDS is characterized by the persistence of female reproductive organs derivatives in a 46,XY subject due to the failure of the Mullerian duct to regress in utero. To date, 53 different mutations of the anti-Mullerian hormone (AMH) gene, including the present one, have been identified.Clinical caseA 2-week-old male presented with bilateral cryptorchidism and normal male external genitalia. His karyotype was 46,XY. hCG stimulation test was normal. At age 1 year and 4 months, he underwent laparoscopic surgery which revealed a uterus and fallopian tubes. The anti-Mullerian hormone (AMH) level was undetectable (<0.01 ng/mL). Diagnosis of Persistent Mullerian Duct Syndrome, probably due to an AMH mutation, was made.Genetic studiesA unique homozygous T to G base substitution was found at position 2219, near the middle of the exon 5, changing codon CTG to CGG in anti-Mullerian hormone (AMH) gene. This mutation causes leucine to be converted to arginine at position 426 belonging to a (L)RA(L)LLLKALQ highly conserved sequence in the AMH gene. Both parents are heterozygous for the mutation.ConclusionPersistent Mullerian Duct Syndrome (PMDS) is a rare cause of bilateral cryptorchidism, when in doubt the existence of Mullerian derivatives should be explored by laparoscopy. Assay of serum AMH helps to distinguish between mutations of AMH and AMH receptor. If serum AMH is very low or undetectable, sequencing of the AMH gene usually confirms the presence of a mutation.     

Spondylar dysplasia in type X collagenopathy

Background. The type X collagen gene (COL10A1) is currently known as the disease-causing gene of metaphyseal dysplasia type Schmid (MDS), whereas a mutation of COL10A1 has been reported to cosegregate with a disease phenotype of mild spondylometaphyseal dysplasia (SMD) in a Japanese family.¶Objective. To elucidate whether or not spondylar dysplasia is common in patients with mutations of COL10A1.¶Materials and methods. We re-evaluated the radiological manifestations in six patients with mutations of COL10A1, who had been previously reported as having MDS.¶Results. Two of six patients showed mild platyspondyly in infancy and early childhood. In both patients, the spondylar dysplasia tended to normalize with age, but mild alterations of the vertebral bodies persisted, even into late childhood. The other radiological manifestations of both patients were identical to those of MDS.¶Conclusion. Our observation suggests that mild spondylar dysplasia may not be uncommon in MDS.