Neuroradiological, neurophysiological and molecular findings in infantile Krabbe disease: two case reports

Krabbe disease is an autosomal recessive neurodegenerative disorder due to a defect of the lysosomal enzyme β-galactocerebrosidase (β-GALC). Depending on the age of onset, the disease is classified into infantile and later-onset forms. We report neuroradiological, neurophysiological and molecular findings in two Greek patients with the infantile form of Krabbe disease. The index patients presented at the age of 3.5 and 6 months, respectively, due to developmental delay. Magnetic resonance imaging (MRI) of the first patient’s brain demonstrated signs of leukodystrophy, while nerve conduction velocities (NCVs) were significantly decreased. The second patient’s MRI at the age of 4 months was initially normal, but at 18 months demonstrated leukodystrophic alterations as well, whereas NCVs were also significantly delayed. In both patients, a severe decrease in β-GALC, activity supported the diagnosis of Krabbe disease, while the final diagnosis was confirmed by molecular genetic testing. Two homozygous mutations of the GALC gene, the c.411_413delTAA [p.K139del] mutation in the first patient, and the c.749T>C [p.I250T] mutation in the second patient, were identified. At their last follow-up visit at the age of 4 and 6 years, respectively, both patients were bedridden and quadri-plegic, suffering from frequent respiratory tract infections and fed through a gastrostomy. Both mutations found in homozygosity in these two unrelated patients of Greek ancestry, could pinpoint a common origin. Genotyping of patients with Krabbe disease is important, in order to contribute to the creation of a European mutation database and to further study possible genotype-phenotype correlations of the disease.

Long-term response in biochemical markers of bone turnover during enzyme replacement therapy in a case-series of patients with Gaucher disease type I from Northern Greece

BACKGROUND

Gaucher disease (GD) is a lysosomal storage disorder characterized by severe skeletal complications. Bone complications are an important cause of morbidity of GD and are thought to result from imbalance in bone remodeling. The objective of this case series was to analyze the long-term effect of enzyme replacement therapy on chemokines MIP-1a and MIP-1b, cytokines IL-3, IL-6, IL-10, and IL-12, osteoprotegerin (OPG) and osteocalcin (BGP), chitotriosidase, quantitative ultrasound sonography (QUS), bone magnetic resonance imaging (MRI) and dual-energy X-ray absorptiometry (DXA) in patients with GD in Northern Greece. In addition, the study aimed in investigating possible relationship between the above mentioned parameters.

PATIENTS AND METHODS

Seven patients with GD type I (three males and four females) were included in the study. Mean age was 26.29 ± 15.34 years (range 7-47 years). Six patients were receiving enzyme replacement therapy (ERT), with 40-60 IU/kg of imiglucerase weekly, for a mean period of 36 months prior to study initiation. One patient started ERT after his inclusion in the study. The levels of MIP-1a, MIP-1b, IL-3, IL-6, IL-10, IL-12, OPG, BGP, chitotriosidase, bone imaging parameters assessed with two different techniques (QUS and DXA) and MRI data were estimated at baseline (T₀) and after two years on ERT.

RESULTS

Chitotriosidase, MIP-1a, and IL-6 levels decreased in all patients after two years of ERT (p =0.05). In contrast, OPG and BGP levels increased (p =0.04 and p =0.02, respectively). Bone mineral density (BMD) demonstrated a progressive improvement with regards to the Z-score in all patients (p =0.05). The decrease in the plasma levels of MIP-1a strongly correlated with a decrease in the plasma levels of chitotriosidase. Additionally, decreased plasma levels of IL-6 were correlated with increased Z-score both at baseline (T₀) as well as two years later, in all patients. There was no correlation between MRI findings and any inflammatory biomarker.

CONCLUSIONS

Measurement of serum markers in patients with GD under ERT could be used as an auxiliary tool in the monitoring of bone involvement, in combination with MRI imaging and BMD. However, larger studies involving higher numbers of GD patients are needed to confirm these conclusions. Hippokratia 2016, 20(2): 153-159.

The serotonergic system: its role in pathogenesis and early developmental treatment of autism

Autism is a severe childhood disorder already presenting in the first 3 years of life and, therefore, strongly correlated with neurodevelopmental alterations in prenatal, as well as postnatal period. Neurotransmitters hold a pivotal role in development by providing the stimulation needed for synapses and neuronal networks to be formed during the critical period of neuroplasticity. Aberrations of the serotonergic system modify key processes in the developing brain and are strongly implicated in the pathophysiology of developmental disorders. Evidence for the role of serotonin in autism emerges from neuropathological, imaging and genetic studies. Due to its developmental arrest, autism requires early intervention that would, among others, target the disrupted serotonergic system and utilize brain plasticity to elicit clinically important brain changes in children.

Tyrosine hydroxylase deficiency with severe clinical course

Tyrosine hydroxylase (TH) deficiency is a rare autosomal recessive disorder mapped to chromosome 11p15.5. Its clinical expression varies with presentations as dopa-responsive dystonia (recessive Segawa's disease), dopa-responsive infantile parkinsonism, dopa-responsive spastic paraplegia, progressive infantile encephalopathy or dopa-non-responsive dystonia. We describe a 7-year-old boy with progressive infantile encephalopathy and non-responsiveness to dopamine. The patient demonstrated generalized hypotonia, pyramidal tract dysfunction and temperature instability after the second month of life. Dystonia, tremor and oculogyric crises complicated the clinical picture during the following months. Neurotransmitter analysis in CSF disclosed almost undetectable levels of HVA and MHPG, whereas serum prolactin was profoundly increased. Subsequent molecular analysis revealed homozygosity for a missense mutation (c.707T>C) in the TH gene. l-Dopa therapy in both high and low doses resulted in massive hyperkinesias, while substitution with selegiline exerted only a mild beneficial effect. Today, at the age of 7 years, the patient demonstrates severe developmental retardation with marked trunkal hypotonia, hypokinesia and occasionally dystonic and/or hyperkinetic crises. He is the third Greek patient with TH deficiency to be reported. Since all three patients carry the same pathogenetic mutation, a founder effect is suspected.

L-2-Hydroxyglutaric aciduria presenting with severe autistic features

L-2-Hydroxyglutaric aciduria (L-2-HGA) is an autosomal recessive neurometabolic disorder characterized by psychomotor delay, ataxia, macrocephaly and typical neuroradiological findings of subcortical leucoencephalopathy. Recently, the disease causing gene has been discovered (L2HGDH) encoding L-2-hydroxyglutarate dehydrogenase. We present a 3-year-old boy with L-2-HGA, who demonstrated macrocephaly, noted already in utero with ultrasound. Cranial MRI demonstrated diffuse subcortical encephalopathy with increased signal of the subcortical white matter. Subsequent metabolic screening revealed increased levels of L-2-HGA, and genomic DNA analysis demonstrated two missense mutations in L-2-HGDG. Patient's further motor development was mildly impaired, whilst his speech development was profoundly impaired (first words at the age of 2 years). Since the age of 2 years he started demonstrating autistic repetitive behaviors and movements, increasing aloofness to his environment and limitations in the variety of spontaneous activity (CARS score: 44/60-severe autism). Autism has not so far been described in L-2-HGA and may be considered as an additional feature of the phenotypic spectrum.

Ethylmalonic encephalopathy: clinical and biochemical observations

Ethylmalonic encephalopathy (EE) is a rare, recently defined inborn error of metabolism which affects the brain, gastrointestinal system and peripheral blood vessels and is characterized by a unique constellation of clinical and biochemical features. A 7-month-old male, who presented with psychomotor retardation, chronic diarrhea and relapsing petechiae is described with the objective of highlighting the biochemical and neuroradiological features of this disorder as well as the effect of high-dose riboflavin therapy. Urinary organic acid analysis revealed markedly increased excretion of ethylmalonic acid, isobutyrylglycine, 2-methylbutyrylglycine and isovalerylglycine. Acylcarnitine analysis in dried blood spots showed increased butyrylcarnitine. Short-chain acyl-CoA dehydrogenase (SCAD) activity in muscle was normal as were mitochondrial OXPHOS enzyme activities in cultured skin fibroblasts. In skeletal muscle the catalytic activity of complex II was decreased. Brain MRI revealed bilateral and symmetrical atrophy in the fronto-temporal areas, massive enlargement of the subarachnoid spaces and hyperdensities on T (2) sequences of the basal ganglia. Mutation analysis of the ETHE1 gene demonstrated homozygosity for the Arg163Gly mutation, confirming the diagnosis of EE at a molecular level. On repeat MRI, a significant deterioration was seen, correlating well with the clinical deterioration of the patient.

Possible genotype-phenotype correlations in children with mild clinical course of Canavan disease

Canavan disease is characterised as a rare, neurodegenerative disease that usually causes death in early childhood. It is an autosomal recessive disorder due to an aspartoacylase (ASPA) deficiency. The causative gene has been mapped to chromosome 17 pter-p13. Here we describe three affected children from two Greek families with an unusually mild course of Canavan disease. All children presented with muscular hypotonia and macrocephaly. Diagnosis was based on elevated N-acetylaspartate in urine, reduced aspartoacylase activity in fibroblasts, and marked white matter changes on cerebral imaging. All three affected individuals exhibited continuous psychomotor development without any regression. Genetic analyses revealed compound heterozygous mutations (Y288 C; F295 S) in two individuals. The Y288 C variant was previously described in a child with macrocephaly, mild developmental delay, increased signal intensity in the basal ganglia, partial cortical blindness and retinitis pigmentosa, and slightly elevated N-acetylaspartate in the urine. Demonstration of the same variant in two unusually mildly affected Canavan disease patients and absence of this variant in 154 control chromosomes suggest a possible pathogenic role in mild Canavan disease. In the third individual, two homozygous sequence variants were identified, which comprise the known G274R mutation and a novel K213E variant.

Cerebellar agenesis and diabetes insipidus

We report on a 7-year-old female, born after a normal pregnancy at term, previously referred because of delayed psychomotor development. MRI revealed isolated cerebellar agenesis (CA) with only minute tissue remnants of the anterior vermis/paravermian anterior quadrangular lobes and pontine hypoplasia. The patient demonstrated truncal ataxia, saccadic ocular pursuit and mild gaze evoked nystagmus. At the age of 2.5 years, the girl achieved independent walking, though with a markedly ataxic gait; at the same age diabetes insipidus was recognized and appropriately treated. This association has not been reported before. At the ages of 3.5 and 6.5 years, her developmental quotient (DQ) was 65 and 60, respectively, with a very poor vocabulary and cerebellar dysarthria. The term "agenesis" is problematic as several reports describe considerable cerebellar tissue remnants and may include pontocerebellar hypoplasia. A literature review disclosed only a few patients with CA (defined in a strict sense) diagnosed in vivo by MRI. It is questionable whether asymptomatic CA occurs.

Serial magnetic resonance imaging findings in mucopolysaccharidosis IIIB (Sanfilippo's syndrome B)

Sanfillippo B syndrome (mucopolysaccharidosis (MPS) III, type B) is characterized by mild expression of the characteristic 'Hurler' phenotype and a severe central nervous system involvement. We report three patients with Sanfilippo B syndrome, referred to our clinic because of peculiar facies, delay in language development and behavioral problems, at the ages of 4, 3 and 5 years, respectively. At presentation they manifested clinical features of MPS, severe developmental retardation, radiological features of dysostosis mutiplex, as well as neurophysiological findings suggestive of carpal tunnel syndrome and sensorineural hearing impairment. Due to marked urinary excretion of heparan sulfate, as well as deficiency of alpha-N-acetylglucosaminidase in leukocytes, the diagnosis of Sanfilippo B syndrome was made. Serial brain magnetic resonance imaging (MRI) at different ages demonstrated white matter abnormalities, cortical atrophy and ventricular enlargement in all three patients, while other findings included thickening of the diploe in two patients and callosal atrophy, basal ganglia involvement, cerebellar changes and dilatation of venous sinuses in one patient. Although the combination of the above MRI findings is highly suggestive of a MPS, they carry a little predictive value in the different clinical stages of MPS IIIB.