Gaucher disease patient with myoclonus epilepsy and a novel mutation

Progressive myoclonus epilepsy in Gaucher Disease due to a new Gly-Gly mutation causing loss of an Exonic Splicing Enhancer

BACKGROUND

Patients with Gaucher Disease (GD) exhibit three phenotypes, including type 1 (non-neuronopathic), type 2 (acute neuronopathic), and type 3 (subacute neuronopathic).

AIM

Identifying which GBA changes represent benign polymorphisms and which may result in disease-causing mutations is essential for diagnosis and genotype/phenotype correlations but is often challenging.

RESULTS

Here, we describe a patient with type 3 GD, presenting with drug-resistant epilepsy, who bears a set of GBA polymorphic variants including the novel c.363A > G (Gly82Gly) synonymous mutation. In silico predictions, mRNA and functional studies revealed that the new Gly82Gly mutation causes skipping of GBA exon 4, leading to a severe reduction of the wild type GBA mRNA. This is the first report of a synonymous change causing GD through loss of an exonic splicing enhancer sequence. The synonymous mutation is in trans with the Asn188Ser missense mutation, thus making the Asn188Ser responsible for the patient's phenotype and strengthening the association of Asn188Ser with the particular neurological phenotype of type 3 GD.

CONCLUSION

We strengthen the association of Asn188Ser with the type 3 GD phenotype and progressive myoclonus epilepsy. Our data confirm that in silico predictions and mRNA analysis are mandatory in discriminating pathological mutations from the background of harmless polymorphisms, especially synonymous changes.

Three mutations of adult type 1 Gaucher disease found in a Chinese patient: A case report

RATIONALE

Gaucher disease (GD), characterized by glucosylceramide accumulation in the macrophage-monocyte system, is caused by glucosidase b acid (GBA) gene mutations which lead to the deficiency of lysosomal enzyme glucocerebrosidase. The mutation spectrum of GBA in Chinese patients is quite different from those seen in Jewish and non-Jewish Caucasian patients. Thus, it is relatively hard to diagnose GD in Chinese.

PATIENT CONCERNS

A 24-year-old Chinese female with intermittent abdominal distension and progressive decrease in strength but without neurologic symptoms was initially referred for femoral head necrosis on the right feet. Laboratory examinations results indicated panhematopenia. Bone marrow aspiration smear and biopsy specimen found typical "wrinkled" Gaucher cells. Molecular-genetic testing of GBA gene revealed 3 mutations including R159W (c. 475 C > T), V1230G (c. 689T > G), and G241A (c. 721G > A).

DIAGNOSES

On the basis of these findings and clinical manifestations, the final diagnosis of type 1 GD was made.

INTERVENTIONS

Enzyme replacement therapy (ERT) with velaglucerase α was carried out after the diagnosis of type 1 GD.

OUTCOMES

The platelet and hemoglobin levels were restored by ERT.

LESSONS

To our knowledge, this is the first report of GD patient carrying 3 mutations in Chinese. These mutations in GBA in the present case imply a potential pool of patients with GD with this mutation in Chinese.

The progressive myoclonic epilepsies

Progressive myoclonic epilepsies are a group of disorders characterised by a relentlessly progressive disease course until death; treatment-resistant epilepsy is just a part of the phenotype. This umbrella term encompasses many diverse conditions, ranging from Lafora body disease to Gaucher's disease. These diseases as a group are important because of a generally poor response to antiepileptic medication, an overall poor prognosis and inheritance risks to siblings or offspring (where there is a proven genetic cause). A correct diagnosis also helps patients and their families to accept and understand the nature of their disease, even if incurable. Here, we discuss the phenotypes of these disorders and summarise the relevant specific investigations to identify the underlying cause.

Occasional seizures, epilepsy, and inborn errors of metabolism

Seizures are a common paediatric problem, with inborn errors of metabolism being a rare underlying aetiology. The clinical presentation of inborn errors of metabolism is often associated with other neurological symptoms, such as hypotonia, movement disorders, and cognitive disturbances. However, the occurrence of epilepsy associated with inborn errors of metabolism represents a major challenge that needs to be identified quickly; for some cases, specific treatments are available, metabolic decompensation might be avoided, and accurate counselling can be given about recurrence risk. Some clinical presentations are more likely than others to point to an inborn error of metabolism as the cause of seizures. Knowledge of important findings at examination, and appropriate biochemical investigation of children with seizures of uncertain cause, can aid the diagnosis of an inborn error of metabolism and ascertain whether or not the seizures are amenable to specific metabolic treatment.

A monozygotic twin pair with highly discordant Gaucher phenotypes

We describe monozygotic twin sisters, born to consanguineous Moroccan parents, who are highly discordant for the manifestations of Gaucher disease. Both carry Gaucher genotype N188S/N188S. One has severe visceral involvement, epilepsy, and a cerebellar syndrome. Her twin does not manifest any symptoms or signs of Gaucher disease but suffers from type 1 diabetes mellitus. The concurrence of a mild Gaucher mutation with a severe phenotype, as well as the occurrence of highly discordant phenotypes in a pair of monozygotic twins, is discussed.