The Concurrent and Longitudinal Relationship between Perinatal Sleep Difficulties and Depression in a Large Sample of High-Risk Women in South Africa

INTRODUCTION

Perinatal depression and sleep difficulties are common among studies conducted in high income countries (HIC). This study examines the relationship between sleep difficulties and depression during the perinatal period and over an eight-year follow-up period in South Africa, a middle income country.

METHOD

A population cohort of 1238 pregnant women (mean age = 26.33) in 24 township neighborhoods in South Africa were recruited and reassessed six times over the next 8 years post birth with follow-up rates of 96-83%. The relationship between maternal depressed mood and sleep difficulties was examined over time, as well as the relationship of sleep with other socioeconomic, environmental, and psychiatric risk factors.

RESULTS

Thirty-five percent of the women reported sleep difficulties during the perinatal period; whereas only 8% reported sleep difficulties at 8-year follow-up. Perinatal sleep difficulties were associated with lower income, lower educational attainment, less access to electricity, more food insecurity, higher rates of interpersonal violence and HIV, alcohol consumption, and depressed mood at 8 years. However, the severity of depressed mood was the strongest predictor of sleep problems longitudinally and cross-sectionally, after accounting for all other risk factors.

CONCLUSIONS

We found that the severity of depressed mood is highly associated with sleep difficulties from pregnancy to 8 years post-birth and in a linear relationship, so that higher depressed mood is associated with more sleep problems.

TRIAL REGISTRATION

ClinicalTrials.gov registration: # NCT00996528.

Fumarase Deficiency: A Safe and Potentially Disease Modifying Effect of High Fat/Low Carbohydrate Diet

Fumarate hydratase deficiency (FHD) caused by biallelic alterations of the FH (fumarate hydratase) gene is a rare disorder of the tricarboxylic acid cycle, classically characterized by encephalopathy, profound psychomotor retardation, seizures, a spectrum of brain abnormalities and early death in childhood. Less common milder phenotypes with moderate cognitive impairment and long-term survival have been reported. In addition, heterozygous mutations of the FH gene are responsible for hereditary leiomyomatosis and renal cell cancer (HLRCC). There is currently no recommended disease modifying treatment for FHD and only isolated reports of unsuccessful dietary modifications. Herein, we describe the safe and possibly disease modifying effect of a high fat, low carbohydrate diet in a 14-year-old female with severe FHD.

Unique presentation of cutis laxa with Leigh-like syndrome due to ECHS1 deficiency

Clinical finding of cutis laxa, characterized by wrinkled, redundant, sagging, nonelastic skin, is of growing significance due to its occurrence in several different inborn errors of metabolism (IEM). Metabolic cutis laxa results from Menkes syndrome, caused by a defect in the ATPase copper transporting alpha (ATP7A) gene; congenital disorders of glycosylation due to mutations in subunit 7 of the component of oligomeric Golgi (COG7)-congenital disorders of glycosylation (CDG) complex; combined disorder of N- and O-linked glycosylation, due to mutations in ATPase H+ transporting V0 subunit a2 (ATP6VOA2) gene; pyrroline-5-carboxylate reductase 1 deficiency; pyrroline-5-carboxylate synthase deficiency; macrocephaly, alopecia, cutis laxa, and scoliosis (MACS) syndrome, due to Ras and Rab interactor 2 (RIN2) mutations; transaldolase deficiency caused by mutations in the transaldolase 1 (TALDO1) gene; Gerodermia osteodysplastica due to mutations in the golgin, RAB6-interacting (GORAB or SCYL1BP1) gene; and mitogen-activated pathway (MAP) kinase defects, caused by mutations in several genes [protein tyrosine phosphatase, non-receptor-type 11 (PTPN11), RAF, NF, HRas proto-oncogene, GTPase (HRAS), B-Raf proto-oncogene, serine/threonine kinase (BRAF), MEK1/2, KRAS proto-oncogene, GTPase (KRAS), SOS Ras/Rho guanine nucleotide exchange factor 2 (SOS2), leucine rich repeat scaffold protein (SHOC2), NRAS proto-oncogene, GTPase (NRAS), and Raf-1 proto-oncogene, serine/threonine kinase (RAF1)], which regulate the Ras-MAPK cascade. Here, we further expand the list of inborn errors of metabolism associated with cutis laxa by describing the clinical presentation of a 17-month-old girl with Leigh-like syndrome due to enoyl coenzyme A hydratase, short chain, 1, mitochondria (ECHS1) deficiency, a mitochondrial matrix enzyme that catalyzes the second step of the beta-oxidation spiral of fatty acids and plays an important role in amino acid catabolism, particularly valine.

Leigh-Like Syndrome Due to Homoplasmic m.8993T>G Variant with Hypocitrullinemia and Unusual Biochemical Features Suggestive of Multiple Carboxylase Deficiency (MCD)

Leigh syndrome (LS), or subacute necrotizing encephalomyelopathy, is a genetically heterogeneous, relentlessly progressive, devastating neurodegenerative disorder that usually presents in infancy or early childhood. A diagnosis of Leigh-like syndrome may be considered in individuals who do not fulfil the stringent diagnostic criteria but have features resembling Leigh syndrome.We describe a unique presentation of Leigh-like syndrome in a 3-year-old boy with elevated 3-hydroxyisovalerylcarnitine (C5-OH) on newborn screening (NBS). Subsequent persistent plasma elevations of C5-OH and propionylcarnitine (C3) as well as fluctuating urinary markers were suggestive of multiple carboxylase deficiency (MCD). Normal enzymology and mutational analysis of genes encoding holocarboxylase synthetase (HLCS) and biotinidase (BTD) excluded MCD. Biotin uptake studies were normal excluding biotin transporter deficiency. His clinical features at 13 months of age comprised psychomotor delay, central hypotonia, myopathy, failure to thrive, hypocitrullinemia, recurrent episodes of decompensation with metabolic keto-lactic acidosis and an episode of hyperammonemia. Biotin treatment from 13 months of age was associated with increased patient activity, alertness, and attainment of new developmental milestones, despite lack of biochemical improvements. Whole exome sequencing (WES) analysis failed to identify any other variants which could likely contribute to the observed phenotype, apart from the homoplasmic (100%) m.8993T>G variant initially detected by mitochondrial DNA (mtDNA) sequencing.Hypocitrullinemia has been reported in patients with the m.8993T>G variant and other mitochondrial disorders. However, persistent plasma elevations of C3 and C5-OH have previously only been reported in one other patient with this homoplasmic mutation. We suggest considering the m.8993T>G variant early in the diagnostic evaluation of MCD-like biochemical disturbances, particularly when associated with hypocitrullinemia on NBS and subsequent confirmatory tests. An oral biotin trial is also warranted.

Utility of next-generation sequencing technologies for the efficient genetic resolution of haematological disorders

Next-generation sequencing (NGS) has now evolved to be a relatively affordable and efficient means of detecting genetic mutations. Whole genome sequencing (WGS) or whole exome sequencing (WES) offers the opportunity for rapid diagnosis in many paediatric haematological conditions, where phenotypes are variable and either a large number of genes are involved, or the genes are large making sanger sequencing expensive and labour-intensive. NGS offers the potential for gene discovery in patients who do not have mutations in currently known genes. This report shows how WES was used in the diagnosis of six paediatric haematology cases. In four cases (Diamond-Blackfan anaemia, congenital neutropenia (n = 2), and Fanconi anaemia), the diagnosis was suspected based on classical phenotype, and NGS confirmed those suspicions. Mutations in RPS19, ELANE and FANCD2 were found. The final two cases (MYH9 associated macrothrombocytopenia associated with multiple congenital anomalies; atypical juvenile myelomonocytic leukaemia associated with a KRAS mutation) highlight the utility of NGS where the diagnosis is less certain, or where there is an unusual phenotype. We discuss the advantages and limitations of NGS in the setting of these cases, and in haematological conditions more broadly, and discuss where NGS is most efficiently used.

Update on transcobalamin deficiency: clinical presentation, treatment and outcome

Transcobalamin (TC) transports cobalamin from blood into cells. TC deficiency is a rare autosomal recessive disorder usually presenting in early infancy with failure to thrive, weakness, diarrhoea, pallor, anemia, and pancytopenia or agammaglobulinemia. It can sometimes resemble neonatal leukemia or severe combined immunodeficiency disease. Diagnosis of TC deficiency is suspected based on megaloblastic anemia, elevation of total plasma homocysteine, and blood or urine methylmalonic acid. It is confirmed by studying the synthesis of TC in cultured fibroblasts, or by molecular analysis of the TCN2 gene. TC deficiency is treatable with supplemental cobalamin, but the optimal type, route and frequency of cobalamin administration and long term patient outcomes are unknown. Here we present a series of 30 patients with TC deficiency, including an update on multiple previously published patients, in order to evaluate the different treatment strategies and provide information about long term outcome. Based on the data presented, current practice appears to favour treatment of individuals with TC deficiency by intramuscular injections of hydroxy- or cyanocobalamin. In most cases presented, at least weekly injections (1 mg IM) were necessary to ensure optimal treatment. Most centres adjusted the treatment regimen based on monitoring CBC, total plasma homocysteine, plasma and urine methylmalonic acid, as well as, clinical status. Finally, continuing IM treatment into adulthood appears to be beneficial.

Mitochondrial dysfunction in the skeletal muscle of a mouse model of Rett syndrome (RTT): implications for the disease phenotype

Rett syndrome (RTT) is a severe neurodevelopmental disorder, predominantly caused by mutations in the X-linked Methyl-CpG-binding protein 2 (MECP2) gene. Patients present with numerous functional deficits including intellectual disability and abnormalities of movement. Clinical and biochemical features may overlap with those seen in patients with primary mitochondrial respiratory chain disorders. In the late stages of the disorder, patients suffer from motor deterioration and usually require assisted mobility. Using a mouse model of RTT (Mecp2(tm1Tam)), we studied the mitochondrial function in the hind-limb skeletal muscle of these mice. We identified a reduction in cytochrome c oxidase subunit I (MTCO1) at both the transcript and protein level, in accordance with our previous findings in RTT patient brain studies. Mitochondrial respiratory chain (MRC) enzyme activity of complexes II+III (COII+III) and complex IV (COIV), and glutathione (GSH) levels were significantly reduced in symptomatic mice, but not in the pre-symptomatic mice. Our findings suggest that mitochondrial abnormalities in the skeletal muscle may contribute to the progressive deterioration in mobility in RTT through the accumulation of free radicals, as evidenced by the decrease in reduced glutathione (GSH). We hypothesise that a diminution in GSH leads to an accumulation of free radicals and an increase in oxidative stress. This may impact on respiratory chain function and contribute in part to the progressive neurological and motor deterioration seen in the Mecp2-mutant mouse. Treatment strategies aimed at restoring cellular GSH levels may prove to be a novel target area to consider in future approaches to RTT therapies.

Congenital disorder of glycosylation type Ia: heterogeneity in the clinical presentation from multivisceral failure to hyperinsulinaemic hypoglycaemia as leading symptoms in three infants with phosphomannomutase deficiency

We describe three patients with congenital disorder of glycosylation (CDG) type Ia, all of whom had persistent hyperinsulinaemic hypoglycaemia responding to diazoxide therapy as a common feature. The first patient, an infant girl, presented with recurrent vomiting, failure to thrive, liver impairment, hypothyroidism and a pericardial effusion. The second patient, also female, had a milder disease with single organ involvement, presenting as isolated hyperinsulinaemic hypoglycaemia, not associated with any cognitive impairment. The third patient, a boy presented with multi-organ manifestations including congenital hypothyroidism, persistent hyperinsulinaemic hypoglycaemia, coagulopathy, olivopontocerebellar hypoplasia and recurrent pancreatitis. All three patients had a type 1 serum transferrin isoform pattern, and were subsequently found to have low phosphomannomutase activity, confirming the diagnosis of CDG type Ia. Our findings emphasize that CDG should be considered as a differential diagnosis in patients with persistent hyperinsulinaemic hypoglycaemia and that it may even occasionally be the leading symptom in CDG Ia.

Updating the profile of C-terminal MECP2 deletions in Rett syndrome

OBJECTIVES

This study aimed to compare the phenotype of Rett syndrome cases with C-terminal deletions to that of cases with different MECP2 mutations and to examine the phenotypic variation within C-terminal deletions.

METHODS

Cases were selected from InterRett, an international database and from the population-based Australian Rett Syndrome Database. Cases (n=832) were included if they had a pathogenic MECP2 mutation in which the nature of the amino acid change was known. Three severity scale systems were used, and individual aspects of the phenotype were also compared.

RESULTS

Lower severity was associated with C-terminal deletions (n=79) compared to all other MECP2 mutations (e.g. Pineda scale C-terminals mean 15.0 (95% CI 14.0-16.0) vs 16.2 (15.9-16.5). Cases with C-terminal deletions were more likely to have a normal head circumference (odds ratio 3.22, 95% CI 1.53 - 6.79) and weight (odds ratio 2.97, 95% CI 1.25-5.76). Onset of stereotypies tended to be later (median age 2.5 years vs 2 years, p<0.001 from survival analysis), and age of learning to walk tended to be earlier (median age 1.6 years vs 2 years, p=0.002 from survival analysis). Those with C-terminal deletions occurring later in the region had lower average severity scores than those occurring earlier in the region.

CONCLUSION

In terms of overall severity C-terminal deletion cases would appear to be in the middle of the range. In terms of individual aspects of phenotype growth and ability to ambulate appear to be particular strengths. By pooling data internationally this study has achieved the case numbers to provide a phenotypic profile of C-terminal deletions in Rett syndrome.

The common BDNF polymorphism may be a modifier of disease severity in Rett syndrome

BACKGROUND

Rett syndrome (RTT) is caused by mutations in the transcriptional repressor methyl CpG-binding protein 2 (MECP2). Brain-derived neurotrophic factor (BDNF) is a neurotrophic factor playing a major role in neuronal survival, neurogenesis, and plasticity, and it has been shown that BDNF expression is regulated by MeCP2 through a complex interaction. A common polymorphism of BDNF (Val66Met [p.V66M]) has been found to correlate with severity and course of several neuropsychiatric disorders.

METHODS

We examined the association between disease severity score, assessed by the modified Percy score, and BDNF polymorphism, using regression methods, in 125 mutation-positive patients with RTT from the Australian Rett Syndrome Database and an Israeli cohort.

RESULTS

Those who were heterozygous (Val/Met) had slightly more severe disease than those who were homozygous for the wild-type (Val/Val) BDNF polymorphism (increased severity score 2.1, p = 0.09). In those with p.R168X, a commonly occurring MECP2 mutation in RTT, there was a 6-point increase in severity score for those who were heterozygous for the BDNF polymorphism, both unadjusted (p = 0.02) and adjusted for age (p = 0.03). Individuals with the p.R168X mutation and heterozygous for the BDNF polymorphism were also at an increased risk of seizure onset (hazard ratio 5.3, 95% confidence interval 1.6-17.7) compared with those homozygous for the wild-type BDNF allele.

CONCLUSIONS

In addition to mutation type and degree of X-chromosome skewing, the common brain-derived neurotrophic factor (BDNF) polymorphism appears to be another genetic modifier of Rett syndrome (RTT) severity. This suggests that BDNF function may play a significant role in the pathogenesis of RTT.

Costeff optic atrophy syndrome: new clinical case and novel molecular findings

3-Methylglutaconic aciduria (MGA) encompasses a heterogeneous group of disorders, often coinciding with elevated levels of urinary 3-methylglutaric acid. Type I MGA is a disorder of leucine metabolism, while the biological basis for the MGA is unclear for the other types (MGA types II-V). MGA type III (Costeff optic atrophy syndrome, autosomal recessive optic atrophy-3 or optic atrophy plus syndrome, OMIM 258501) is distinguished by early bilateral optic atrophy, later-onset spasticity, extrapyramidal dysfunction, ataxia, and occasional cognitive deficits. It is caused by homozygous mutations in the optic atrophy 3 gene (OPA3). We present a case of a patient with MGA who has infantile-onset optic atrophy, ataxia, extrapyramidal movements and spasticity, but with normal intellect. Sequencing of the patient's DNA revealed a homozygous nonsense mutation c.415C>T (p.Q139X) in exon 2 of transcript 2 of the OPA3 gene, as well as a common silent polymorphism c.231T>C in the same exon. This is the first nonsense mutation found in OPA3. The molecular findings in OPA3 are also reviewed, including mutations in OPA3 that result in autosomal dominant optic atrophy and cataract (ADOAC). The recessive mode of inheritance of MGA type III as a result of the p.Q139X mutation is supported by the carrier status of the unaffected father.

Glutaric aciduria type I: outcome following detection by newborn screening

Glutaric aciduria type I (GA I), a cerebral organic acidaemia with the potential for severe neurological consequences, can now be detected by tandem mass spectrometry newborn screening. Early detection with implementation of careful management strategies appears to lessen the likelihood of neurological damage. We assessed the outcome in all 10 GA I patients detected in New South Wales during the last decade. Three patients were detected clinically and 7 by newborn screening. Diagnosis was confirmed by detection of significantly elevated urinary 3-hydroxybutyrate and glutarate in urine, isolated elevation of glutarylcarnitine in plasma, typical clinical and MRI findings in several, and mutation analysis or enzyme analysis on cultured skin fibroblasts in 4 cases. The birth frequency was 1:90,000. Following diagnosis, treatment was initiated in all children with oral carnitine (100 mg/kg per day) and a low-protein diet supplemented with a lysine-free, low-tryptophan amino acid formula. Disability was assessed in fields of motor, cognitive and speech development and scored according to Kyllerman. Clinically diagnosed patients were all symptomatic, with severity scores (out of 9) of 3, 5 and 9. Six of seven patients detected by newborn screening are asymptomatic, 4 being aged 2-6 years. One patient had a severe decompensation at 7 months, despite full management advice and treatment, and later died. Our data support previous findings that early diagnosis reduces neurological complications, but show that even with early diagnosis and careful management severe complications may ensue in some.

Potential of AAV vectors in the treatment of metabolic disease

Inborn errors of metabolism are collectively common, frequently severe and in many instances difficult or impossible to treat. Accordingly, there is a compelling need to explore novel therapeutic modalities, including gene therapy, and examine multiple phenotypes where the risks of experimental therapy are outweighed by potential benefits to trial participants. Among available gene delivery systems recombinant AAV shows special promise for the treatment of metabolic disease given the unprecedented efficiencies achieved in transducing key target tissues, such as liver and muscle, in small animal models. To date over 30 metabolic disease phenotypes have been investigated in small animal studies with complete phenotype correction being achieved in a substantial proportion. Achieving adequately widespread transduction within the central nervous system, however, remains a major challenge, and will be critical to realization of the therapeutic potential of gene therapy for many of the most clinically troubling metabolic disease phenotypes. Despite the relatively low immunogenicity of AAV vectors, immune responses are also emerging as a factor requiring special attention as efforts accelerate toward human clinical translation. Four metabolic disease phenotypes have reached phase I or I/II trials with one, targeting lipoprotein lipase deficiency, showing exciting early evidence of efficacy.

A structured simple form for ordering genetic tests is needed to ensure coupling of clinical detail (phenotype) with DNA variants (genotype) to ensure utility in publication and databases

Researchers and clinicians ideally need instant access to all the variation in their gene/locus of interest to efficiently conduct their research and genetic healthcare to the highest standards. Currently much key data resides in the laboratory books or patient records around the world, as there are many impediments to submitting this data. It would be ideal therefore if a semiautomated pathway was available, with a minimum of effort, to make the deidentified data publicly available for others to use. The Human Variome Project (HVP) meeting listed 96 recommendations to work toward this situation. This article is planned to initiate a strategy to enhance the collection of phenotype and genotype data from the clinician/diagnostic laboratory nexus. Thus, the aim is to develop universally applicable forms that people can use when investigating patients for each inherited disease, to assist in satisfying many of the recommendations of the HVP Meeting [Cotton et al., 2007]. We call for comment and collaboration in this article.

Transient multiple acyl-CoA dehydrogenation deficiency in a newborn female caused by maternal riboflavin deficiency

A newborn female presented on the first day of life with clinical and biochemical findings consistent with multiple acyl-CoA dehydrogenase deficiency (MADD). Riboflavin supplementation corrected the biochemical abnormalities 24 h after commencing the vitamin. In vitro acylcarnitine profiling in intact fibroblasts both in normal and riboflavin depleted media showed normal oxidation of fatty acids excluding defects in electron transfer flavoprotein (ETF), or ETF ubiquinone oxidoreductase (ETF:QO), or a genetic abnormality in flavin metabolism. In addition, sequencing of the genes encoding ETF and ETF:QO in the proband did not reveal any pathogenic mutations. Determination of the maternal riboflavin status after delivery showed that the mother was riboflavin deficient. Repeat testing done two years after the infant's birth and while on a normal diet showed that the mother was persistently riboflavin deficient and showed a typical MADD profile on plasma acylcarnitine testing. A possible genetic defect in riboflavin transport of metabolism in the mother is postulated to be the cause of the transient MADD seen in the infant. Sequencing of the SLC16A12, RFK and FLAD1 genes encoding key enzymes in riboflavin transport of metabolism in the mother did not identify any pathogenic mutations. The underlying molecular basis of the mother's defect in riboflavin metabolism remains to be established.

Low citrulline may not be diagnostic of ornithine transcarbamylase deficiency: a case report

A newborn boy with family history of severe ornithine transcarbamylase (OTC) deficiency was investigated prospectively and managed aggressively at birth based on an existing protocol for at risk neonates. Undetectable citrulline levels at birth suggested that the infant was affected; however, normal plasma glutamine and urine orotic acid levels confused the diagnosis to some extent. Mutation testing confirmed that the patient did not have OTC deficiency. Thus the low plasma citrulline level did not validate our initial biochemical suspicion of OTC deficiency, and this highlights the importance of considering all available clinical, biochemical and molecular evidence in determining disease status.

Early progressive encephalopathy in boys and MECP2 mutations

MECP2 mutations mainly occur in females with Rett syndrome. Mutations have been described in 11 boys with progressive encephalopathy: seven of nine with affected sisters and two de novo. The authors report four de novo occurrences: three pathogenic and one potentially pathogenic. Common features include failure to thrive, respiratory insufficiency, microcephaly, and abnormal motor control. MECP2 mutations should be assessed in boys with progressive encephalopathy and one or more of respiratory insufficiency, abnormal movements or tone, and intractable seizures.

Lesch-Nyhan disease in a 20-year- old man incorrectly described as developing 'cerebral palsy' after general anaesthesia in infancy

Lesch-Nyhan disease (LND) is a rare X-linked recessive genetic disorder caused by a deficiency of hypoxanthine-guanine phosphoribosyltransferase (HPRT) enzyme. The classic clinical condition is characterized by cognitive impairment, hypotonia at rest, choreoathetosis, hyperuricaemia and the hallmark symptom of severe and involuntary self-mutilation. We describe a man with LND who was initially thought to have suffered from a dyskinetic cerebral palsy after an uncomplicated inguinal herniorrhaphy under general anaesthesia at 5 1/2 months of age. In the absence of overt self-injurious behaviour, the diagnosis was not considered for nearly two decades. The diagnosis of LND was established at 20 years of age through clinical review, biochemical examinations and molecular analysis. HPRT haemolysate activity was 7.6% of the normal control, suggesting that he had a milder variant of the disease. Mutation analysis of the HPRT gene revealed a novel missense mutation, c.449T > G in exon 6 (p.V150G). Cascade testing of family members revealed that the mother was heterozygous for the mutation but two siblings (a brother and a sister) did not carry the sequence mutation. Whether the onset of neurological abnormalities in this particular case can be attributed to the general anaesthesia is discussed.

Rett syndrome: clinical review and genetic update

Rett syndrome (RS) is a severe neurodevelopmental disorder that contributes significantly to severe intellectual disability in females worldwide. It is caused by mutations in MECP2 in the majority of cases, but a proportion of atypical cases may result from mutations in CDKL5, particularly the early onset seizure variant. The relationship between MECP2 and CDKL5, and whether they cause RS through the same or different mechanisms is unknown, but is worthy of investigation. Mutations in MECP2 appear to give a growth disadvantage to both neuronal and lymphoblast cells, often resulting in skewing of X inactivation that may contribute to the large degree of phenotypic variation. MeCP2 was originally thought to be a global transcriptional repressor, but recent evidence suggests that it may have a role in regulating neuronal activity dependent expression of specific genes such as Hairy2a in Xenopus and Bdnf in mouse and rat.

Lost in translation: translational interference from a recurrent mutation in exon 1 of MECP2

BACKGROUND

Rett syndrome (RTT) is an X linked neuro-developmental disorder affecting mostly girls. Mutations in the coding region of MECP2 are found in 80% of classic RTT patients. Until recently, the region encoding MECP2 was believed to comprise exons 2, 3, and 4 with the ATG start site located at the end of exon 2 (MeCP2_e2).

METHODS

Recent reports of another mRNA transcript transcribed from exon 1 (MeCP2_e1) prompted us to screen exon 1 among RNA samples from 20 females with classic or atypical RTT.

RESULTS

A previously reported 11 base pair deletion in exon 1 was detected in one subject with a milder phenotype. Although RNA expression for both protein isoforms was detected from the mutant allele, evaluation of MeCP2 protein in uncultured patient lymphocytes by immunocytochemistry revealed that MeCP2 protein production was restricted to only 74-76% of lymphocytes. X chromosome inactivation studies of genomic DNA revealed similar XCI ratios at the HUMARA locus (73:27 with HpaII and 74:26 with McrBC). We have demonstrated that translation but not transcription of the MeCP2_e2 isoform is ablated by the 11 nucleotide deletion, 103 nucleotides upstream of the e2 translation start site.

CONCLUSIONS

These findings reveal that nucleotides within the deleted sequence in the 5'-UTR of the MeCP2_e2 transcript, while not required for transcription, are essential for translation.

OPA3 mutation screening in patients with unexplained 3-methylglutaconic aciduria

We have screened 13 patients with neurological abnormalities and 3-methylglutaconic aciduria (3MGA) for mutations in the OPA3 gene, which are known to be the cause of Costeff syndrome (optic atrophy, chorea and spasticity; type III 3MGA). We aimed to explore whether mutations in the OPA3 gene are present in patients with 3MGA but without classic Costeff syndrome. OPA3 mutations (IVS1-1G>C) were identified in 2 patients with the classic phenotype of type III 3MGA, but not in the other 11 patients with differing non-Costeff phenotypes associated with developmental delay and neurological signs and symptoms as described. We identified a previously described sequence variation in the OPA3 gene (c.231T>C) in 12/13 patients. The alteration was homozygous in 8/12 and heterozygous in 4/12. This alteration was also found in 60 of 98 normal control alleles. In a single patient, a novel sequence variation in the 5' UTR was identified, (c.-38A>G). Our studies suggest that the c.231T>C sequence variation is of no clinical significance, whereas the significance of the 5' UTR sequence variation remains open to speculation. Our study of the OPA3 gene in patients with 3MGA without Costeff syndrome suggests that mutations in OPA3 are not a common cause of 3MGA in the absence of signs of Costeff syndrome.

Trisomy 21 and Rett syndrome: a double burden

Rett syndrome is a severe neurodevelopmental disorder generally affecting girls. Affected individuals are apparently normal at birth but later pass through a period of regression with loss of hand and communication skills and the development of hand stereotypies and dyspraxia. Mutations in the methyl-CpG binding protein 2 (MECP2) gene, have now been found to cause Rett syndrome in up to 80% of classical cases. We report a girl with Down syndrome, one of three children with birth defects in a family of five. From the age of 18 months she developed symptomatology considered by her primary physician to be very characteristic of Rett syndrome. However, this remained a clinical diagnosis till the age of 12 years. Laboratory confirmation of the dual diagnosis, which includes a R168X mutation in the MECP2 gene in addition to trisomy 21, has now been possible. The presence of one neurological or developmental disorder does not necessarily preclude a diagnosis of Rett syndrome.

Myelodysplastic syndrome (RARS) with +i(12p) abnormality in a patient 10�months after diagnosis and successful treatment of a mediastinal germ cell tumor (MGCT)

We report on a 21-year-old man with a mediastinal germ cell tumor (MGCT) who developed a myelodysplastic syndrome (MDS) (refractory anemia with ringed sideroblasts, RARS) 10 months after the start of successful treatment with cisplatin, etoposide, ifosfamide, and paclitaxel. A very rare early occurrence of a therapy-related MDS was suspected. Cytogenetic analysis of the bone marrow revealed an aberrant karyotype, showing a deletion in 12p, an isochromosome 5p, as well as gain of an isochromosome 12p. Isochromosome 12p is a specific aberration frequently observed in MGCT. It also was described in patients who developed hematological transformation of a mediastinal germ cell tumor. In this report the association between mediastinal germ cell tumors and hematological malignancies including the possibility of a common genetic origin is discussed.

Describing the phenotype in Rett syndrome using a population database

BACKGROUND

Mutations in the MECP2 gene have been recently identified as the cause of Rett syndrome, prompting research into genotype-phenotype relations. However, despite these genetic advances there has been little descriptive epidemiology of the full range of phenotypes.

AIMS

To describe the variation in phenotype in Rett syndrome using four different scales, by means of a population database.

METHODS

Using multiple sources of ascertainment including the Australian Paediatric Surveillance Unit, the development of an Australian cohort of Rett syndrome cases born since 1976 has provided the first genetically characterised population based study of Rett syndrome. Follow up questionnaires were administered in 2000 to families and used to provide responses for items in four different severity scales.

RESULTS

A total of 199 verified cases of Rett syndrome were reported between January 1993 and July 2000; 152 families provided information for the follow up study. The mean score using the Kerr scale was 22.9 (SD 4.8) and ranged from 20.5 in those under 7 years to 24.2 in those over 17 years. The mean Percy score was 24.9 (SD 6.6) and also increased with age group from 23.0 to 26.9. The mean Pineda score was 16.3 (SD 4.5) and did not differ by age group. The mean WeeFIM was 29.0 (SD 11.9), indicating extreme dependence, and ranged from 18 to 75.

CONCLUSION

We have expanded on the descriptive epidemiology of Rett syndrome and shown different patterns according to the severity scale selected. Although all affected children are severely functionally dependent, it is still possible to identify some variation in ability, even in children with identified MECP2 mutations.

Clinical approach to inborn errors of metabolism presenting in the newborn period

Inborn errors of metabolism are individually rare, but collectively are responsible for significant levels of paediatric morbidity and mortality. More than 400 biochemically diverse inborn errors of metabolism have been identified. Recent advances in the diagnosis and treatment of these disorders have substantially improved the prognosis for many of them. Paediatricians and neonatologists play a vital role in identifying which patients need to be investigated. The diagnosis of an inborn error of metabolism often needs to be established quickly in order to prevent death or permanent neurological sequelae, and this should be carried out in collaboration with a specialized unit. The present review provides a practical approach to the recognition and investigation of neonates in whom an inborn error may be present. We also provide guidelines for the stabilization and initial management of infants at high risk of a metabolic disorder.

Sleep dysfunction in Rett syndrome: lack of age related decrease in sleep duration

The sleep patterns of a cohort of 83 Rett syndrome females were characterized using a sleep diary for 7 consecutive days and nights and compared with normative sleep data. The mean total sleep time of the cohort was 10.75 h, daytime sleep 0.77 h, sleep efficiency 89.7%, and sleep latency 0.52 h. When subjects were categorized according to age and Rett syndrome classification, there was no significant difference in their sleep characteristics. There was a significant difference in the percentage predicted total sleep time (P<0.001) and Z scores for total sleep time (P<0.001), when subjects were categorized according to age and compared with normal children. The Rett syndrome subjects in this study did not show the age related decrease in total and daytime sleep time seen in normal children. The immature sleep pattern demonstrated in this cohort, may be a consequence of arrested brain development.

Medium-term open label trial of L-carnitine in Rett syndrome

Treatment strategies in Rett syndrome so far have been essentially symptomatic and supportive. In order to establish the medium-term effects of L-carnitine, an open label trial was performed in a cohort of 21 Rett syndrome females, with a control group of 62 Rett syndrome females of a similar age, for a 6-month period. Compared with the Rett syndrome controls, treatment with L-carnitine led to significant improvements in sleep efficiency (P=0.027), especially in the subjects with a baseline sleep efficiency less than 90%, energy level (P<0.005) and communication skills (P=0.004). There was no significant difference in the subject's level of physical activity, hand function or in the quality of life of the subject's parents. In addition, before and after comparisons of the treatment group showed improvements in expressive speech (P=0.011). Treatment with L-carnitine seems to be of significant benefit in a subgroup of girls with Rett syndrome. In these girls, small but discernible improvements may be of considerable importance to their parents and carers.

Coronary arteriographic findings in symptomatic and asymptomatic subjects with coronary artery calcification

The relation of coronary artery calcification with the presence of symptoms of coronary artery disease and its angiographic severity is not clear. We studied 37 apparently healthy, asymptomatic subjects that were found by digital cinefluoroscopy to have coronary calcium and compared to age- and sex-matched group of patients with coronary calcium and symptomatic coronary artery disease. Normal coronary arteries and non-obstructive lesions only were found in 12/37 (32.4%) and 11/37 (29.7%) asymptomatic subjects vs. 1/37 (2.7%) and 2/37 (5.4%) patients; P<0.001 and P<0.012, respectively. Obstructive lesions were more rare in asymptomatic subjects than in patients, 14/37 (37.8%) vs. 34/37 (91.9%) (P<0.0001), as well as total occlusions, 2/37 (5.4%) vs. 10/37 (27%) (P<0.024). Median worst lesion stenosis was 30% in asymptomatic subjects and 95% in patients (P<0.0001). In asymptomatic usual cardiovascular risk subjects, coronary calcium detection by digital cinefluoroscopy is accompanied by a relatively high probability of obstructive disease, although less severe angiographically than in age- and sex-matched catheterized patients with symptomatic coronary artery disease.

A case of multiple congenital anomalies in association with Rett syndrome confirmed by MECP2 mutation screening

Rett syndrome (RTT) is a severe neurodevelopmental disorder. Apparently normal at birth, girls with RTT undergo developmental regression and acquire a neurological and behavioural phenotype that has been used to define clinical diagnostic criteria for the disorder. Recently mutations in the methyl-CpG binding protein 2 gene (MECP2), located on Xq28 have been identified in females with RTT. We report a girl whose clinical course was complicated by congenital abnormalities of the respiratory tract and gastrointestinal system. In addition neurological abnormalities were evident in the newborn period. By the age of 3 years she had developed a phenotype very suggestive of RTT, but had not demonstrated deceleration of head growth and the development of expressive language was prevented by the presence of the tracheostomy. The clinical impression of RTT was confirmed by the recent finding of a mutation in the MECP2 gene. This case report highlights the importance of considering the clinical diagnosis of RTT even in the presence of other conditions and emphasises that girls with RTT may not be normal from birth.

Guidelines for reporting clinical features in cases with MECP2 mutations

An international group recommends that papers relating phenotypes to genotypes involving mutations in the X chromosome gene MECP2 should provide a minimum data set reporting the range of disturbances frequently encountered in Rett Syndrome. A simple scoring system is suggested which will facilitate comparison among the various clinical profiles. Features are described which should prompt screening for MECP2 mutations.

Rett syndrome: clinical characteristics and recent genetic advances

PURPOSE

Rett syndrome is a neurodevelopmental disorder that occurs almost exclusively in females. In recent years there has been increased knowledge concerning the multidisciplinary management of individuals with Rett syndrome. The aim of this paper is to provide an update of the clinical phenotype, natural history and current genetic understanding of the disorder.

RESULTS/CONCLUSION

Rett syndrome is thought to be the second most common cause of severe mental retardation in females after Down syndrome. it now appears that females with RS present with a much broader phenotype than originally described. Recently, mutations in the MECP2 gene encoding X-linked methyl-CpG-binding-protein 2 have been identified in some females with Rett syndrome.

Spinocerebellar ataxia type 7: a distinctive form of autosomal dominant cerebellar ataxia with retinopathy and marked genetic anticipation

When a child presents with progressive ataxia, there is a broad differential diagnosis and a very long list of potential investigations. Spinocerebellar ataxia type 7 presenting in infancy is a rare condition where a presumptive diagnosis can be made based on the clinical features alone. These include rapidly progressive ataxia, retinopathy and autosomal dominant inheritance with marked genetic anticipation of paternal origin. The father of the infant may manifest minimal symptoms at a time when the infant is severely affected. Diagnosis is confirmed by the demonstration of an expansion of a CAG repeat in the coding region of the gene on chromosome 3p. We present a case to illustrate the diagnostic difficulties. Antenatal diagnosis was performed in two subsequent pregnancies.

Family data in Rett syndrome: association with other genetic disorders

BACKGROUND

Rett syndrome is a neurological disorder, almost exclusively affecting girls.

METHODOLOGY

Between 1993 and 1995 pedigree data were obtained from families of girls registered with the Australian Rett syndrome database.

RESULTS

Although 21 individual disorders were reported to be present in family members of affected girls, there was no apparent clustering of the same disorder in different families. However it was certain that a geneticist had been involved in only 10.9% of cases.

CONCLUSIONS

Mutations in the MECP2 gene have now been reported in a proportion of sporadic cases. Thus, it will be important to examine this phenotype-genotype correlation in the Australian cohort. Where a mutation is found, prenatal diagnosis in a subsequent pregnancy will be a possibility. Using the Australian population database and in conjunction with the clinical genetic services in each state it is planned to contact families with an affected girl to offer testing and counselling.

Genetic defects causing mitochondrial respiratory chain disorders and disease

Genetic mitochondrial defects of the respiratory chain show marked phenotypic variability. Laboratory diagnosis is complicated and includes biochemical screening tests, tissue histopathology, functional enzyme studies, and molecular tests where available. Normal respiratory chain function necessitates the co-ordinated expression of over 100 different gene loci, and the interaction of two genetic systems, the nuclear and mitochondrial genomes. Thus genetic counselling for the mitochondrial disorders is extremely challenging. In this review, the classes of mitochondrial and nuclear defects that give rise to functional abnormalities of the mitochondrial respiratory chain are discussed, with specific instructive examples described in some detail.

Intramolecular activation of a Ca(2+)-dependent protein kinase is disrupted by insertions in the tether that connects the calmodulin-like domain to the kinase

Ca(2+)-dependent protein kinases (CDPK) have a calmodulin-like domain (CaM-LD) tethered to the C-terminal end of the kinase. Activation is proposed to involve intramolecular binding of the CaM-LD to a junction sequence that connects the CaM-LD to the kinase domain. Consistent with this model, a truncated CDPK (DeltaNC) in which the CaM-LD has been deleted can be activated in a bimolecular interaction with an isolated CaM-LD or calmodulin, similar to the activation of a calmodulin-dependent protein kinase (CaMK) by calmodulin. Here we provide genetic evidence that this bimolecular activation requires a nine-residue binding segment from F436 to I444 (numbers correspond to CPK-1 accession number L14771). Two mutations at either end of this core segment (F436/A and VI444/AA) severely disrupted bimolecular activation, whereas flanking mutations had only minor effects. Intramolecular activation of a full-length kinase was also disrupted by a VI444/AA mutation, but surprisingly not by a F436/A mutation (at the N-terminal end of the binding site). Interestingly, intramolecular but not bimolecular activation was disrupted by insertion mutations placed immediately downstream of I444. To show that mutant enzymes were not misfolded, latent kinase activity was stimulated through binding of an antijunction antibody. Results here support a model of intramolecular activation in which the tether (A445 to G455) that connects the CaM-LD to the kinase provides an important structural constraint and is not just a simple flexible connection.

Type 2 Gaucher disease: the collodion baby phenotype revisited

The association of Gaucher disease, the inherited deficiency of lysosomal glucocerebrosidase (EC 3.2.1.45), and congenital ichthyosis was first noted a decade ago. Subsequently, a null allele type 2 Gaucher mouse was generated that also exhibited ichthyotic skin, confirming that the skin disorder and enzyme deficiency were directly related. This paper details the clinical and molecular characterisation of 6 cases of type 2 Gaucher disease presenting with the collodion baby phenotype. The identified mutant glucocerebrosidase alleles include two novel mutations (S196P and R131L) and two rare point mutations (R120W and R257Q), as well as alleles resulting from recombination with the nearby glucocerebrosidase pseudogene. There is significant genotypic heterogeneity in this rare subset of patients with type 2 Gaucher disease. Gaucher disease should be considered in the differential diagnosis of congenital ichthyosis in the newborn period.