Analyses of a multi-parent population derived from two diverse alfalfa germplasms: testcross evaluations and phenotype-DNA associations.

In a previous study, we showed that the genetic variation present in the Medicago sativa subsp. sativa Peruvian and M. sativa subsp. falcata WISFAL germplasms could be used to improve forage yields when favorable alleles were recombined and used in hybrid combination with cultivated alfalfa. In this paper, we present testcross forage yield and fall growth data for two seasons of a C0 population generated after intermating the Peruvian x WISFAL population for several generations. In addition, we conducted marker-trait association analysis as an attempt to identify Peruvian and WISFAL genomics regions affecting the targeted traits. Five and seven genomic regions were found significantly associated with forage yield and fall growth, respectively. In the case of fall growth, alleles from both accessions were positively associated with plant height. However, more alleles from WISFAL were positively associated with forage yield than from Peruvian. WISFAL is known for its winter hardiness and genomic regions with large effects on winter survival may have masked the effect of forage yield from Peruvian. The fact that most of the genomic regions discovered in this study have been previously associated with traits involved in winter hardiness validates our findings and suggests that associations between DNA fragments and agronomic traits can be detected without the necessity of developing bi-parental mapping populations.

Mutations in the neurofilament light chain gene (NEFL) cause early onset severe Charcot-Marie-Tooth disease.

Neurofilament light chain polypeptide (NEFL) is one of the most abundant cytoskeletal components of the neuron. Mutations in the NEFL gene were recently reported as a cause for autosomal dominant Charcot-Marie-Tooth type 2E (CMT2E) linked to chromosome 8p21. In order to investigate the frequency and phenotypic consequences of NEFL mutations, we screened 323 patients with CMT or related peripheral neuropathies. We detected six disease associated missense mutations and one 3-bp in-frame deletion clustered in functionally defined domains of the NEFL protein. Patients have an early onset and often a severe clinical phenotype. Electrophysiological examination shows moderately to severely slowed nerve conduction velocities. We report the first nerve biopsy of a CMT patient with a de novo missense mutation in NEFL, and found an axonal pathology with axonal regeneration clusters and onion bulb formations. Our findings provide further evidence that the clinical variation observed in CMT depends on the gene mutated and the specific type of mutation, and we also suggest that NEFL mutations need to be considered in the molecular evaluation of patients with sporadic or dominantly inherited CMT.

Neurologic and psychiatric manifestations in a family with a mutation in exon 2 of the guanosine triphosphate-cyclohydrolase gene.

OBJECTIVE: To investigate the range of clinical features to correlate genotypic and phenotypic manifestations in hereditary progressive and/or levodopa-responsive dystonia due to a defect in the guanosine triphosphate-cyclohydrolase (GCH1) gene. DESIGN AND SETTING: A large family from Texas was studied in an ambulatory setting by clinicians in genetics, neurology, and psychiatry using structured interviews and examinations. PATIENTS: The family was selected after neurometabolic investigations of a young boy (proband) with foot dystonia and fatigue and his father, who had a long history of anxiety and depression. Results of metabolic studies showed decreased levels of metabolites of biopterin and biogenic amines in cerebrospinal fluid. Subsequently, a novel mutation (37-base pair deletion) in exon 2 of the GCH1 gene was demonstrated in 11 family members. There was no observed female sex bias, but there was a wide variability of motor dysfunctions in family members. Approximately 50% had clinical deafness and a similar number had significant psychiatric dysfunction, including depression and anxiety. CONCLUSION: Study of additional families with hereditary progressive and/or levodopa-responsive dystonia using modern molecular methods will be necessary to confirm the neuropsychiatric spectrum of this disorder, in which important clinical features may be unrecognized and thus inappropriately managed.

Encephalopathy associated with respiratory syncytial virus bronchiolitis.

Respiratory syncytial virus is an extremely common cause of childhood respiratory infections resulting in significant morbidity and mortality. Although apnea is a well-known complication in young infants with respiratory syncytial virus bronchiolitis, the encephalopathy associated with this infection is not well recognized. Our study reveals an incidence of encephalopathy of 1.8% in a total of 487 patients with respiratory syncytial virus bronchiolitis studied over a period of almost 4 years. Seizures were the presenting complication. Based on our study of a cohort of children with respiratory syncytial virus bronchiolitis, we believe that neurologic complications, although relatively uncommon, represent a significant component of this common childhood illness. Furthermore, respiratory syncytial virus has been shown to release several mediators that could directly or indirectly be neurotoxic and induce an encephalopathy associated with the respiratory illness.

Sphenoid sinusitis masquerading as migraine headaches in children.

The sphenoid sinus is often referred to as the "neglected sinus." Isolated sphenoid sinusitis is a rare disease with potentially devastating complications. It occurs at an incidence of about 2.7% of all sinus infections. Although headache is the most common presenting symptom, there is no typical headache pattern. Three cases of children with isolated sphenoid sinusitis presenting with acute, subacute, and chronic headache symptoms are presented. The sensory innervation of the sphenoid sinus is derived from the ophthalmic and maxillary branches of the trigeminal nerve, which may explain the pathophysiology of the headache, similar to the trigeminovascular pain theory of migraine. There are few reports on sphenoid sinusitis and headache; however, modern neuroimaging has made this probably under-recognized disorder easier to diagnose and treat. Although the diagnosis can be difficult to differentiate from migraine headache, early and appropriate treatment usually results in an excellent outcome without morbidity.

Recurrent isolated ptosis in presumed ophthalmoplegic migraine of childhood.

PURPOSE: To report a rare case of isolated, recurrent unilateral eyelid ptosis as the sole manifestation of ophthalmoplegic migraine in a healthy young girl. DESIGN: Single observational case report with review of the literature. TESTING: Serologic evaluation, electromyographic, nerve conduction and Tensilon testing, magnetic resonance and computerized tomographic imaging, and magnetic resonance angiography were performed. MAIN OUTCOME MEASURES: Four-year descriptive history of recurrent eyelid ptosis. RESULTS: Between 1994 and 1998, seven discrete episodes of right upper eyelid ptosis without ophthalmoplegia or pupil abnormality occurred. On each occasion, spontaneous resolution occurred over a period of 6 to 10 weeks. Extensive clinical and laboratory evaluation, including testing for myasthenia gravis and magnetic resonance cerebral angiography, was unremarkable. CONCLUSIONS: Recurrent isolated ptosis is a rare manifestation of presumed ophthalmoplegic migraine in childhood. As far as we are aware, this has not been previously reported.

Pulmonary hypoplasia in the myogenin null mouse embryo.

Although fetal breathing movements are required for normal lung development, there is uncertainty concerning the specific effect of absent fetal breathing movements on pulmonary cell maturation. We set out to evaluate pulmonary development in a genetically defined mouse model, the myogenin null mouse, in which there is a lack of normal skeletal muscle fibers and thus skeletal muscle movements are absent in utero. Significant decreases were observed in lung:body weight ratio and lung total DNA at embryonic days (E)14, E17, and E20. Reverse transcriptase/polymerase chain reaction, in situ immunofluorescence, and electron microscopy revealed early lung cell differentiation in both null and wild-type lungs as early as E14. However at E14, myogenin null lungs had decreased 5'-bromo-2-deoxyuridine incorporation compared with that of wild-type littermates, whereas at E17 and E20, increased Bax immunolabeling and terminal deoxyribonucleotidyl transferase-mediated dUTP-biotin nick-end labeling staining were detected in the myogenin null mice but not in the wild-type littermates. These observations highlight the importance of skeletal muscle contractile activity in utero for normal lung organogenesis. Null mice lacking the muscle-specific transcription factor myogenin exhibit a secondary effect on lung development such that decreased lung cell proliferation and increased programmed cell death are associated with lung hypoplasia.

Human bHLH transcription factor gene myogenin (MYOG): genomic sequence and negative mutation analysis in patients with severe congenital myopathies.

The myogenin gene encodes an evolutionarily conserved basic helix-loop-helix transcription (bHLH) factor that is required for differentiation of skeletal muscle, and its homozygous deletion in mice results in perinatal death from respiratory failure due to the lack of muscle fibers. Since the histology of skeletal muscle in myogenin null mice is reminiscent of that found in severe congenital myopathy patients, many of whom also die of respiratory complications, we sought to test the hypothesis that an aberrant human myogenin (myf4) coding region could be associated with some congenital myopathy conditions. With PCR amplification, we found similarly sized PCR products for the three exons of the myogenin gene in DNA from 37 patient and 40 control individuals. In contrast to previously reported sequencing of human myogenin (myf4), we describe with automated sequencing several base differences in flanking and coding regions plus an additional 659 and 498 bp in the first and second introns, respectively, in all 37 patient and 40 control samples. We also find a variable length (CA)-dinucleotide repeat in the second intron, which may have utility as a marker for future linkage studies. In summary, no causative mutations were detected in the myogenin coding locus of genomic DNA from 37 patients with severe congenital myopathy.

Rolandic type cerebral palsy in children as a pattern of hypoxic-ischemic injury in the full-term neonate.

Magnetic resonance images (MRIs) of the brains of 11 patients aged from 1 week to 12 years with a distinctive type of cerebral palsy were selected based on distribution of cerebral lesions, which were restricted to bilateral perirolandic cortical and subcortical regions, including frequent symmetric involvement of basal ganglia and ventrolateral nucleus of thalami. Retrospectively, the perinatal history and clinical features were reviewed to correlate clinical data with this distinctive pattern of brain injury. Clinically affected neonates had an encephalopathy associated with a severe perinatal asphyxial event. Older children with cerebral palsy survived a similar perinatal course and demonstrated spastic quadriparesis with bulbar or pseudobulbar involvement, lack of verbal speech and variable delays in cognitive development. The distribution of hypoxic-ischemic lesions involving bilateral perirolandic regions, basal ganglia, and thalami, appears to correlate with increased metabolic areas of primary myelination in full-term neonates, but not with arterial border zones nor a single cerebral artery distribution. Myelination is a critical process in maturing brain associated with marked increase in tissue respiration and thus greater susceptibility to oxygen deprivation. It is believed that the extent of hypoxic-ischemic brain injury is determined principally by brain maturity and regional metabolic rates at time of insult and this correlates with active myelination in full-term neonates. This study confirms previous data from neuropathologic literature and recent reports of neuroimaging studies of asphyxiated neonates. In addition, retrospective analysis of the clinical data enables recognition of a type of cerebral palsy that might be the hallmark of hypoxic-ischemic injury in term neonates.

Mutations in the early growth response 2 (EGR2) gene are associated with hereditary myelinopathies.

The early growth response 2 gene (EGR2) is part of a multigene family encoding Cys2His2 type zinc-finger proteins and may play a role in the regulation of cellular proliferation. Egr2, (also known as Krox20) is the mouse orthologue of human EGR2 and was first identified as an immediate-early response gene, encoding a protein that binds DNA in a sequence-specific manner and acts as a transcription factor. Stable expression of Egr2 is specifically associated with the onset of myelination in the peripheral nervous system (PNS). Egr2(-/-) mice display disrupted hindbrain segmentation and development, and a block of Schwann-cell differentiation at an early stage. We hypothesized that Egr2 may be a transcription factor affecting late myelin genes and that human myelinopathies of the PNS may result from mutations in EGR2. In support of this hypothesis, we have identified one recessive and two dominant missense mutations in EGR2 (within regions encoding conserved functional domains) in patients with congenital hypomyelinating neuropathy (CHN) and a family with Charcot-Marie-Tooth type 1 (CMT1).

Cerebrospinal fluid homovanillic acid levels in rapid-onset dystonia-parkinsonism.

Rapid-onset dystonia-parkinsonism (RDP) is characterized by sudden onset over hours to days of dystonia, dysphagia, dysarthria, and parkinsonism. RDP has been reported by our group in two apparently unrelated families. We now report analysis of cerebrospinal fluid metabolites of dopamine, norepinephrine, and serotonin for mild and severely affected individuals, known asymptomatic gene carriers, and at-risk individuals from both families with RDP. Levels of the dopamine metabolite homovanillic acid (HVA) were decreased in severely affected patients and in some asymptomatic gene carriers. HVA levels increased with treatment in some affected individuals, but this increase did not predict clinical response to carbidopa/levodopa. We suggest that a low HVA level is a biological marker with modest association to the diagnosis of RDP.

X-linked spastic paraplegia due to a mutation (C506T; Ser169Phe) in exon 4 of the proteolipid protein gene (PLP).

A transition C506T was found in exon 4 of the proteolipid protein gene of a boy with spastic paraplegia. This mutation resulted in the substitution of phenylalanine for serine 169, which is in the third transmembrane domain of the proteolipid protein molecule. The mutation apparently arose de novo, as it was absent from his mother.

Aromatic L-amino acid decarboxylase deficiency: clinical features, diagnosis, and treatment of a second family.

Aromatic L-amino acid decarboxylase deficiency is an inborn error of metabolism that leads to combined serotonin and catecholamine deficiency, first described by Hyland et al in 1990. The clinical features, biochemical findings, and treatment of the second family with this condition are reported. Our male patient presented with developmental delay, extreme hypotonia, oculogyric crises, and irritability. The diagnosis of this inborn error of biogenic amine metabolism was accomplished by determining low concentrations of homovanillic, 5-hydroxyindoleacetic acid, and 3-methoxy-4-hydroxyphenyl-ethyleneglycol in cerebrospinal fluid with normal biopterin metabolism and increased L-dopa, in plasma, cerebrospinal fluid, and urine. Greatly reduced activity of aromatic L-amino acid decarboxylase in plasma confirmed this diagnosis. Combined treatment with pyridoxine, tranylcypromine, and bromocriptine produced some clinical improvement.

Autosomal dominant torsion dystonia with onset in infancy.

We report a man and his daughter who had onset of dystonia during the first year of life, primarily involving their legs and consisting of both sustained postures and rhythmical 2-3 Hz twisting movements. They also had eccentric and irregularly shaped pupils, but no other neurological abnormalities. This disorder differs from all familial dystonia syndromes described in the literature, including classic idiopathic torsion dystonia, which has a later age of onset. This disorder probably represents a new autosomal dominant dystonia syndrome.

Severity of medical and neurologic complications as a determinant of neurodevelopmental outcome at 6 and 12 months in very low birth weight infants.

Very low birth weight (n = 154) and term infants (n = 119) had neurologic and developmental assessment at 6 and 12 months of age. Preterm infants with severe neonatal complications were considered to be at high risk, and those with milder complications were considered to be at low risk, for neurodevelopmental abnormality. Compared to term infants, high- and low-risk infants had abnormalities at 6 months in total neurologic score, cranial nerves, motor tone, motor coordination, and reflexes (P < .001). At 12 months, all groups had improved. However, high-risk infants had persistent abnormalities in the same subcategories (P < .001), whereas low-risk infants differed from term infants only in motor tone (P < .001). Bayley developmental scores were different for all groups at 6 months (P < .001), but at 12 months only high-risk infants differed from term infants (P < .01). These results demonstrate improvement in neurologic and developmental scores over time in very low birth weight infants. The degree of neurodevelopmental abnormality and improvement over time is related to severity of neonatal complications in preterm infants.

Variable phenotype of rapid-onset dystonia-parkinsonism.

Rapid-onset dystonia-parkinsonism (RDP) is an autosomal dominant disorder characterized by the rapid onset of dystonic spasms and parkinsonism over a period of a few hours to weeks after their onset. We have seen two additional members of this previously reported family with RDP who present with a more gradual progression of their disorder over 6-18 months. One of these individuals experienced the rapid progression of symptoms 2 years after an initial stabilization of his condition. The RDP phenotype is variable, and presentation may be gradual in some cases. Cerebrospinal fluid neurotransmitter levels in these two and other family members suggest involvement of the dopaminergic pathways in RDP.

In vivo microdialysis and gas chromatography/mass spectrometry for studies on release of N-acetylaspartlyglutamate and N-acetylaspartate in rat brain hypothalamus.

Microdialysis and gas chromatography/mass spectrometry was used for the measurement of extracellular N-acetylaspartate (NAA) and N-acetylaspartylglutamate (NAAG) in rat hypothalamus. The sensitivity of the method for each of these compounds was approximately 5 pmol/30 microliters of dialysate. Baseline NAA concentrations in dialysate were estimated to be approximately 25 pmol/36 microliters, while that for NAAG was at or below the detection limit of 5 pmol/ 36 microliters. In vivo and in vitro calibrations of microdialysis probes showed that the recovery for NAA was approximately 10 percent. For NAAG, the in vitro recovery was 6.3%, and in vivo recovery, 11%. Depolarization stimulation using 100 mM KCl in the microdialysis perfusate was employed to measure extracellular NAA and NAAG concentrations. Extracellular NAA was elevated to approximately 70 pmol/36 microliters dialysate following depolarization. No significant elevation of NAAG was observed. By infusing known amounts of stable isotopically labeled NAAG-d3 via the microdialysis probe and measuring the isotopically labeled catabolic product, NAA-d3, in collected microdialysate, we were able to confirm the existence of one or more hydrolytic enzymes active towards NAAG in the hypothalamus. This finding suggest the possible involvement of active metabolic processes in the relationship between NAAG and NAA releases.

Amoxapine overdose in a young man: a transient mitochondrial abnormality?

Amoxapine is a second-generation tricyclic antidepressant structurally related to the neuroleptic loxapine. It was previously marketed as an alternative to traditional tricyclic antidepressants because of alleged shorter onset of action and fewer cardiotoxic effects. However, various adverse reactions, including cardiac dysrhythmias, renal failure, coma, seizures, and neuroleptic malignant syndrome, were reported during therapy or after acute overdose. A 14-year-old boy ingested 1900 mg of amoxapine and developed seizures, hypertension, hyperpyrexia, altered mental status, myoglobinuria, renal failure, and transient magnetic resonance imaging (MRI) changes suggestive of hypertensive encephalopathy and neuroleptic malignant syndrome. Since mitochondrial disorders can cause multisystem failure, including encephalopathy, renal tubular dysfunction, and myopathy, a transient, toxic disorder of mitochondrial function was considered as the basis for the patient's clinical and MRI changes.