A new mutation of the fukutin gene causing late-onset limb girdle muscular dystrophy

Defects in glycosylations of α-dystroglycan are associated with mutations in several genes, including the fukutin gene (FKTN). Hypoglycosylation of α-dystroglycan results in several forms of muscular dystrophy with variable phenotype. Outside Japan, the prevalence of muscular dystrophies related to aberrations of FKTN is rare, with only eight reported cases of limb girdle phenotype (LGMD2M). We describe the mildest affected patient outside Japan with genetically confirmed LGMD2M and onset of symptoms at age 14. She was brought to medical attention at age 12, not because of muscle weakness, but due to episodes of tachycardia caused by Wolff–Parkinson–White syndrome. On examination, she had rigid spine syndrome, a typical limb girdle dystrophy pattern of muscle weakness, cardiomyopathy, and serum CK levels >2000 IU/L (normal <150 IU/L). A homozygous, novel c.917A>G; p.Y306C mutation in the FKTN gene was found. The case confirms FKTN mutations as a cause of LGMD2M without mental retardation and expands the phenotypic spectrum for LGMD2M to include cardiomyopathy and rigid spine syndrome in the mildest affected non-Japanese patient reported so far.     

A new mutation in the prion protein gene: a patient with dementia and white matter changes

The authors describe the clinical characteristics, MRI abnormalities, and molecular findings in a patient with a novel variant of a two-octarepeat insertion mutation in the prion protein gene. This patient presented with moderately progressive dementia of presenile onset and gait ataxia. MRI showed extensive cortical atrophy and white matter abnormalities. The mutation consists of a two-octarepeat insertion mutation and irregularities in the nucleotide sequence of the octarepeat region.     

A new mutation in the mitochondrial tRNA(Ala) gene in a patient with ophthalmoplegia and dysphagia

We describe a new mutation in the tRNA(Ala) gene, a T-->C transition at nucleotide position 5628, in a 62-year-old woman with late onset chronic progressive external ophthalmoplegia, dysphagia and mild proximal myopathy. The mutation is heteroplasmic and disrupts a highly conserved A-U base pair within the anticodon stem of the tRNA(Ala). Cytochrome c oxidase-negative fibers harbor a significantly higher level of mutated mtDNA than cytochrome c oxidase-positive fibers. This is the first mutation in the tRNA(Ala) gene which satisfies accepted criteria for pathogenicity.     

Novel mutations in the fukutin gene in a boy with asymptomatic hyperCKemia

Mutations in the fukutin gene were first identified in Japanese patients with classic Fukuyama congenital muscular dystrophy, a severe form of congenital muscular dystrophy associated with cobblestone lissencephaly and ocular defects. Patients of different ethnicities and with milder phenotypes, including limb girdle muscular dystrophy and cardiomyopathy without brain impairment, have also been reported. The hallmark of this disorder, regardless of the clinical outcome, is moderate-to-severe hypoglycosylation of alpha-dystroglycan in muscle sections. We describe the case of a boy harboring two novel mutations in fukutin gene and presenting a five-year history of asymptomatic hyperCKemia, without overt muscle, brain or ocular involvement. Genetic investigations, guided by the presence of moderate myopathic changes on muscle biopsy with loss of immunodetectable alpha-dystroglycan, led to a definitive diagnosis. Cardiac and echocardiographic examinations at follow-up disclosed low normal left ventricular function but no active cardiovascular symptoms. We suggest that fukutin mutations should be sought in asymptomatic hyperCKemia and subclinical heart dysfunction.     

A new de novo mutation of the connexin-32 gene in a patient with X-linked Charcot-Marie-Tooth type 1 disease

We report a 26-year-old Italian man with X-linked Charcot-Marie-Tooth (CMT) disease type 1 (CMT-X1) and a negative family history for neuromuscular diseases. Clinical and electrophysiological examinations of the patient's mother and siblings were normal. Molecular analysis by polymerase chain reaction – single-strand conformation polymorphism (PCR-SSCP) on genomic DNA from the patient and all members of his family revealed a C-to-T transition in codon 8 of exon 2 of the connexin-32 (Cx32) gene on the X chromosome only in the patient. This transition in the 5'-coding region, resulting in a Thr-Ile substitution, is likely to be the cause of CMT phenotype in our patient, and it represents a new de novo mutation of the Cx32 gene. Received: 10 February 2000 / Accepted in revised form: 7 April 2000     

A novel mutation in the DYSF gene in a patient with a presumed inflammatory myopathy

Dysferlinopathy, a progressive muscular dystrophy, results from mutations in the Dysferlin gene (DYSF, MIM*603009). Traditional diagnosis relies on the reduction or absence of dysferlin. However, altered dysferlin has been observed in other myopathies, leading to a precise diagnosis through molecular genetics. In this study, we report a patient who was previously misdiagnosed as inflammatory myopathy based on routine clinicopathological examinations alone. However, muscle biopsy specimens were analyzed further by immunohistochemistry of muscular dystrophy‐related proteins, and gene‐targeted next generation sequencing (NGS) was used to correctly identify muscular dystrophy. DNA was sequenced with NGS and the detected mutation was verified by Sanger sequencing. Our targeted NGS found a novel missense mutation (c.5392G > A) in the DYSF gene, allowing correct diagnosis of LGMD2B in our patient. We discovered of a novel missense mutation in the DYSF gene and have broadened the DYSF mutation spectrum, which may be correlated in patients with presumed dysferlinopathy, especially when lymphocytic infiltration is observed.     

A new mutation in the myophosphorylase gene (Asn684Tyr) in a Spanish patient with McArdle's disease.

We have identified a novel missense mutation, an A-T transition at codon 684 in exon 17, changing an encoded asparagine to a tyrosine (Asn684Tyr) in a Spanish patient with typical McArdle's disease. The patient was a compound heterozygote, with a previously-described mutation (Gly204Ser) on the other allele. This report expands the molecular genetic heterogeneity in McArdle's disease, emphasizes the presence of private mutations in specific ethnic groups, and indicates that geographic origin must be considered before undertaking DNA analysis for diagnosis.     

A novel ABCD1 gene mutation in a Chinese-Taiwanese patient with adrenomyeloneuropathy

The ABCD1 gene mutation (previously ALD) has been reported in China, but not previously in Taiwan. This case report describes one Taiwanese patient whose clinical manifestations were compatible with adrenomyeloneuropathy. Direct sequencing for the ABCD1 gene of this patient and his mother detected a novel missense mutation, K513Q, in exon 6, the first such detected in a Taiwanese patient. Previous studies have suggested exon 6 as a possible hot segment of ABCD1 gene mutations in Chinese populations; however, most of the mutations in exon 6 presented as childhood cerebral adrenoleukodystrophy. K513Q is also the first novel mutation located within exon 6 and presenting with adult-onset adrenomyeloneuropathy in Chinese-Taiwanese.     

A new mutation in DNM2 gene in a large Italian family

Neurological Sciences - The Charcot-Marie-Tooth (CMT) disease is the most common inherited peripheral neuropathy with great clinical and genetic heterogeneity. Mutations in DNM2 have been...     

A Portuguese case of Fukuyama congenital muscular dystrophy caused by a multi-exonic duplication in the fukutin gene

Fukuyama congenital muscular dystrophy (FCMD) is one of the most common autosomal recessive diseases among the Japanese population, due to a founder mutation of the fukutin gene (FKTN). Mutations in FKTN are now being described in an increasing number of non-Japanese patients. We report a Portuguese child with FCMD. The diagnosis was supported by clinical, histological, magnetic resonance imaging (MRI) and genetic studies. Genetic analysis of FKTN by Multiplex Ligation Probe Amplification (MLPA) revealed a homozygous duplication from exon 4 to exon 7. This in-frame duplication was confirmed by cDNA analysis. To our knowledge this is the first report of a FCMD case caused by an intragenic gross exonic duplication in the FKTN gene. This report widens the clinical and mutational spectrum in FCMD and corroborates the importance of screening for large deletions and duplications in CMD patients.     

A new stop codon mutation (Y52X) in the myophosphorylase gene in a Greek patient with McArdle's disease.

We identified a novel stop codon mutation in the myophosphorylase gene in a Greek patient with typical symptoms of McArdle's disease. This is the first genetic study of myophosphorylase deficiency in a Greek family, showing that the proband was a compound heterozygous for the common "caucasian" mutation (R49X) and a new nonsense mutation (Y52X), both within exon 1. The new point mutation, a C-to-G transversion at codon 52, converts an encoded tyrosine to a stop codon. Our study confirms that the R49X is also present in the Greek population. The Y52X may represent a private mutation or a common mutation among Greeks. Our data further expand the already remarkable genetic heterogeneity of McArdle's disease. The prevalence of the Y52X mutation in Greek patients with McArdle's disease remains to be determined.     

A new mitochondrial point mutation in the transfer RNA(Leu) gene in a patient with a clinical phenotype resembling Kearns-Sayre syndrome.

OBJECTIVE: To report on the molecular identification of a novel heteroplasmic G-to-A transition at mitochondrial DNA position 3249 in transfer RNA(Leu) gene in a patient with a clinical phenotype resembling Kearns-Sayre syndrome. PATIENT AND METHODS: A 34-year-old patient had been suffering for more than 10 years from progressive visual failure, neurosensorial hearing loss, exercise intolerance, muscle weakness, paresthesia in the lower limbs, and difficulties swallowing. Clinical examination revealed generalized muscle wasting, ptosis, external ophthalmoplegia, and ataxia. Ophthalmologic examination showed dystrophic features in the cornea and retina. In skeletal muscle, morphologic and biochemical studies of the respiratory chain complexes were performed. Polymerase chain reaction, single-strand conformation polymorphism, and direct sequencing were used to screen for mutations in the 22 mitochondrial transfer RNA genes. RESULTS: In skeletal muscle, a significantly decreased catalytic activity of complex I was detected by spectrophotometric analysis and numerous cytochrome c oxidase-negative ragged-red fibers were seen on morphologic examination. A G-to-A substitution 3249 (G3249A) mutation was found in the transfer RNA(Leu) gene of the patient and mutant mitochondrial DNA represented 85% of the total in skeletal muscle but only 45% in leukocytes. The mutation was shown to be present in a small fraction in leukocytes from the unaffected mother and to be absent in leukocytes from the healthy sister. CONCLUSIONS: A causal relationship between a heteroplasmic G3249A transfer RNA(Leu) mutation in a patient suffering from progressive external ophthalmoplegia, retinal dystrophy, ataxia, neurosensorial hearing loss, and muscle wasting is postulated. To our knowledge, the G3249A mutation has never previously been described and was not detected in control subjects.     

A novel compound heterozygous mutation in the DAP12 gene in a patient with Nasu-Hakola disease

A 34-year-old woman showed clinical features characteristic of Nasu-Hakola disease (NHD), also designated polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy (PLOSL). The genetic analysis of the DAP12 gene (TYROBP) identified two heterozygous mutations composed of a previously reported single base deletion of 141G (141delG) in exon 3 and a novel single base substitution of G262T in exon 4, both of which are located on separate alleles. The protein sequence motif search indicated that both mutations encode truncated nonfunctional DAP12 polypeptides. This is the first case of NHD caused by compound heterozygosity for loss-of-function mutations in DAP12.     

A novel mutation in the CLN1 gene in a patient with juvenile neuronal ceroid lipofuscinosis

We describe the clinical, neuropathological and molecular findings from a patient affected with neuronal ceroid lipofuscinosis with a juvenile onset (JNCL). She was a 9-year-old right-handed girl with a normal birth and early developmental milestones. At the age of 4 the early symptoms began. Skin biopsy showed granular osmiophilic deposits (GRODs). Because JNCL with GRODs is caused by mutations in the CNL1 gene, we performed a molecular investigation by direct sequencing of nine exons of the CNL1 gene. This analysis revealed a novel mutation in homozygous form in the exon 7 that caused an aminoacid substitution at codon 222 (Leu → Pro). Direct sequencing of the exon 7 in both parents showed the same substitution in heterozygous form. Received: 30 November 2001, Received in revised form: 8 April 2002, Accepted: 23 April 2002 RID="*" ID="*"These authors contributed equally to this work RID="*" ID="*"These authors contributed equally to this work Correspondence to Prof. Aldo Quattrone, MD     

A mutation in the X-linked Emery-Dreifuss muscular dystrophy gene in a patient affected with conduction cardiomyopathy

A screening for mutation in the X-linked Emery-Dreifuss muscular dystrophy (X-EMD) gene was performed among patients affected with severe heart rhythm defects and/or dilated cardiomyopathy. Patients were selected from the database of the Department of Cardiology of the University Hospital Brno. One patient presented a mutation in the X-EMD gene and no emerin in his skeletal muscle. The patient had a severe cardiac disease but a very mild muscle disorder that had not been diagnosed until the mutations was found. This case shows that mutations in X-EMD gene, as it was shown for autosomal-dominant EMD, can cause a predominant cardiac phenotype.     

A reeler mutant mouse with a new,spontaneous mutation in the reelin gene

In one of our mouse colonies a reeler-like phenotype appeared spontaneously. The brain histology was identical to the known reeler phenotype. Northern and Western blot analysis and a complementation test showed that the defect is located to the reelin gene. Southern blot and PCR analysis together with information obtained from sequence databases revealed that this defective reelin gene had an approximately 24-kb intragenic deletion comprising exons 13-20.     

A SOD1 gene mutation in a patient with slowly progressing familial ALS.

We report a new missense mutation (Gly12Arg) [corrected] in exon 1 of the Cu/Zn superoxide dismutase (SOD1) gene in a 67-year-old patient with familial ALS (FALS). The clinical course showed an unusually slow progression. The enzymatic activity of the mutated SOD1 was 80% of normal. At the molecular level, the Gly12Arg [corrected] mutation occurs in a region outside the active site and may lead to local distortion strain in the protein structure.