Successful Treatment of Intractable Epilepsy with Ketogenic Diet Therapy in Twins with ALG3-CDG

Abstract

Background

Congenital disorders of glycosylation (CDG) is a heterogeneous group of congenital metabolic diseases with multisystem clinical involvement. ALG3-CDG is a very rare subtype with only 24 cases reported so far.

Case

Here, we report two siblings with dysmorphic features, growth retardation, microcephaly, intractable epilepsy, and hemangioma in the frontal, occipital and lumbosacral regions.

Results

We studied two siblings by whole exome sequencing. A pathogenic variant in ALG3 (NM_005787.6: c.165C>T; p.Gly55=) that had been previously associated with congenital glycolysis defect type 1d was identified. Their intractable seizures was controlled by ketogenic diet.

Conclusion

Although prominent findings of growth retardation and microcephaly seen in our patients have been extensively reported before, presence of hemangioma is a novel finding that may be used as an indication for ALG3-CDG diagnosis. Our patients are the first reported cases whose intractable seizures were controlled with ketogenic diet. This report adds ketogenic diet as an option for treatment of intractable epilepsy in ALG3-CDG.

1. Introduction

Congenital disorders of N-linked glycosylation (CDG) is a group of genetic diseases that are associated with hypoglycosylation of proteins and lipids. Isoelectrofocusing of transferrin is used as a screening test for N-glycosylation disorders and the resulting pattern helps to divide the N-linked glycosylation into two groups. Problems in the assembly of glycans and their binding to proteins lead to CDG-I, while problems in processing of glycans lead to CDG-II [1]. There are more than hundred subtypes of N-linked glycosylation disorders [2].

ALG3-CDG (formerly known as CDG-Id) is an autosomal recessive condition caused by mutations in the ALG3 gene on chromosome 3q27. Such mutations result in mannosyl transferase deficiency that leads to the accumulation of truncated oligosaccharides [3].

ALG3-CDG has a phenotypically severe course. Patients have brain, eye, skeletal anomalies, and dysmorphic findings. Although epilepsy has been reported frequently in these patients, it has not been well characterized [4]. Generalized tonic, myoclonic, migratory focal seizures can be seen. Semiology and electroencephalography (EEG) findings may be consistent with West syndrome. Many antiepileptic drugs have been tried, but limited or no response has been achieved [1, 2, 5]. It is known that ketogenic diet may be effective in seizure control in CDG patients, but it is recommended to be used carefully due to the risk of hypoglycemia [6]. To date, 24 ALG3-CDG patients from 14 different families have been reported in the literature (Table 1) [1, 2]. Here, we report two siblings diagnosed with ALG3-CDG, whose seizures were controlled by ketogenic diet.

Table 1.

Main Clinical Findings of ALG3-CDG Patients

	Sex	Developmental Delay	Seizures	Age of seizure onset	Seizure Types	EEG features at onset	Treatment	Treatment response
Patient 1 (This article)	M	+	+	2 mo	Myoclonic, tonic-clonic, spasm	Burst suppression	LEV, PB, B6, VGB, CLB, KD	Seizure free with KD
Patient 2 (This article)	F	+	+	2,5 mo	Spasm, myoclonic, clonic	Burst suppression	LEV, PB, VGB, B6, CLB, KD	Reduction more than 50% with KD
Denecke et al. (2004)	M	+	+	4 mo	Febrile, spasm	burst-suppression (At 2 mo of age)	PB, VGB, VPA	Seizure free with VPA for 3 years, then intractable seizures started again
Schollen et al. (2005)	F	+	+	n.a	n.a	n.a	n.a	Controlled by multi-drug
Sun et al. (2005)	F	Died at 12 days old	-	-	-	-	-	-
Kranz et al. (2007)	F	+	+	Shortly after birth	n.a	n.a	n.a	Intractable
	M	+	+	Shortly after birth	n.a	n.a	n.a	Intractable
Rimella‐Le‐ Huu et al. (2008)	M	+	+	4 mo	Tonic-clonic	bi-occipital and bi-temporal discharges	PB, BZD, VPA	Improvement with VPA
Riess et al. (2013)	F	+	+	3 mo	Focal, generalized tonic and myoclonic	focal seizure arising from the right hemisphere	n.a	Improvement with VPA + LTG (2–3 seizures monthly)
	M	+	+	12 mo	Multiple	n.a	n.a	Intractable
Lepais et al. (2015)	M	Terminated Fetus
	F	n.a	+	n.a	n.a	Disorganized, asymmetrical bacground	n.a	n.a
Fiumara et al. (2016)	F	+	+	1 mo	focal motor and tonic–clonic seizures	Continuous, generalized, slow spike/waves and polyspike waves (NCSE)	PB, VGB	n.a
Barba et al. (2016)	M	+	+	1 mo	Focal tonic, clonic, spasms	Slow background, multifocal spike	PHT, LEV	reduction about 50% with PHT
Alsubhi et al. (2017) (n=7)	3F, 4M	6/7	0/7	-	-	-	-	-
Himmelreich et al. (2019)	M	+	+	2 mo	Spasm	Hypsarrhythmia	B6, prednisolone, VGB, LEV, VPA	Intractable
	F	+	+	6 mo	generalized febrile convulsion	Unremarkable	PB	Partial response
	F	+	+	4 mo	Spasm	Hypsarrhythmia	vitamin B6, sulthiame dexamethasone, VGB	Intractable
	M	+	+	10 mo	Absences, generalized	Normal	LEV	n.a

CLB; Clobazam, KD; ketogenic diet, LEV; levetiracetam, LTG; Lamotrigine, n.a; not achieved, NCSE; nonconvulsive status epilepticus, PB; Phenobarbital, PHT; PhenytoinVPA; valproic acid, VGB; vigabatrin

2. Case Descriptions

2.1. Patient 1

Male infant (one of fraternal twins) was born to consanguineous parents (third cousins) at 38-weeks of gestation (birth weight 3460g). At the age of forty days, he was hospitalized for ten days due to pneumonia. Myoclonic and tonic clonic seizures started on the day he was discharged and he was admitted to our hospital. Physical examination revealed that he had poor eye contact, axial hypotonia, lack of head control, microcephaly (head circumference 36 cm, −2.4 SDS), hypertelorism, retromicrognathia, low-set ears and broad and flattened nasal bridge. In addition, we observed hemangiomas in the frontal, occipital, and lumbosacral regions. Deep tendon reflexes were normal. There was no organomegaly (Table 1).

Levetiracetam treatment was initiated and seizure activity improved, however tonic spasms started on the third day of treatment. Burst suppression pattern was observed in EEG (Figure 1A). Preliminary diagnoses of Ohtahara syndrome and early myoclonic epilepsy were considered. Vitamin B6 (30 mg/kg/g) was added to the treatment.

Figure 1:

EEG images of patient 1 and 2

A: Patient 1 - Burst supression (Before ketogenic diet)

B: Patient 1 - Disorganised background with rare sharp waves at right temporo-parieto-occipital region (After ketogenic diet)

C: Patient 2 - Burst supression (Before ketogenic diet)

D: Patient 2 – Improvement background activity with right anterior temporal sharp waves (After ketogenic diet)

Brain magnetic resonance imaging (MRI) shoved mildly increased subarachnoid space and cavum septum pellucidum (Figure 2A). Complete blood count and biochemical values ​​were within the normal range. Cerebrospinal fluid (CSF) / plasma glucose ratio was 0.7 and CSF lactate level was 1.14 mmol / L (N: 1.1–2.8). Blood ammonia and lactate values ​​were normal. CSF culture and serological examinations were normal. Simultaneous analysis of CSF and plasma amino acid levels, urine organic acids, and acyl-carnitine profile were normal. Ophthalmologic examination revealed the presence of bilateral albinoid fundus. He did not pass the auditory brainstem response test for both ears and bilateral conductive hearing loss was detected. Patent foramen ovale was detected on cardiologic examination.

Figure 2:

Brain MRI images of patient 1 and 2

A: Patient 1 (2 months old), axial T2 MRI image showing mildly increased subarachnoid space and cavum septum pellucidum

B: Patient 2 (2 months old), axial T2 MRI image showing mildly increased subarachnoid space and cavum septum pellucidum

Phenobarbital was added to the treatment protocol to treat continued albeit less frequent spasm seizures. Seizures were controlled and five days after the addition of phenobarbital, the patient was discharged with phenobarbital (5mg/kg/g), levetiracetam (30 mg/kg/g) and B6 (30 mg/kg/g) treatment. During the follow-up, no seizures were observed, his development improved, and hypotonia decreased. Then, at the age of 4.5 months he was admitted to the intensive care unit due to fever and pneumonia. He had deviations in the eyes and frequent seizures in the form of blinking during the day. EEG showed more pronounced multifocal sharp wave activity in the left temporo-parieto-occipital region. Vigabatrin was added to the treatment and phenobarbital treatment was reduced and subsequently discontinued. During the follow-up, the patient experienced recurrent seizures during fevered periods and when he was 8 months old clobazam was added to his treatment to control tonic seizures that occurred every 1–3 days. Three weeks after clobazam was added, there was an evident increase in generalized tonic seizures and myoclonic seizures concomitant with fever. Clobazam treatment was discontinued and ketogenic diet treatment with a lipid: nonlipid ratio of 3:1 was initiated. After the first week of the diet, there were no seizures and his alertness increased. EEG showed disorganised background with rare sharp waves at right temporo-parieto-occipital region (Figure 1B). Total blood ketone body levels was maintained in the range of 3.3–3.7 mmol/L without any adverse effects. Blood glucose and insulin levels were normal. The vigabatrin and phenobarbital treatments were decreased and subsequently discontinued. The patient, who is now 18 months old, is on the 10th month of levetiracetam (30 mg/kg/g) and ketogenic diet treatment and does not exhibit any complications or seizures.

2.2. Patient 2

The first patient’s twin sister was born at 38-weeks gestation and 3260g. She was consulted for developmental delay when she was two months old. This patient had no prior history of seizures. She had microcephaly (head circumference 35 cm, −3.0 SDS), low-set ears, hypertelorism, wide and flattened nasal bridge. Similar to her brother, hemangiomas were observed in the frontal, occipital and lumbosacral regions. She had poor eye contact, axial hypotonia, and could not hold her head. Deep tendon reflexes were normal. There was no organomegaly (Table 1).

Since the patient’s phenotype was similar to her sibling’s, EEG examination at nine weeks old revealed disorganized background rhythm, but no epileptic activity. However, one week later, she had flexor spasms and repeated EEG showed a burst suppression pattern (Figure 1C). Brain MRI shoved mildly increased subarachnoid space and cavum septum pellucidum (Figure 2B) was normal. Complete blood count and biochemical tests were normal. Lactic acid, ammonia, plasma amino acid levels, urine organic acids, and acyl-carnitine profile were normal as well. Phenobarbital treatment was initiated and the seizures did not recur. Similar to her sibling, ophthalmologic evaluation revealed bilateral albinoid fundus. There was a mild mitral insufficiency on cardiologic examination and medullary nephrocalcinosis on the right kidney on renal ultrasonography. Phenobarbital treatment was followed for one month without seizures. Then she was hospitalized with fever and respiratory distress and her seizures recurred. Burst-suppression pattern was observed in the repeated EEG. She had generalized clonic seizures and vitamin B6 (30 mg/kg/g) and topiramate were added to the treatment. Antiepileptic drug doses were titrated due to seizures triggered by fever. Myoclonic seizures and flexor spasms were seen at 6 months of age and EEG showed a burst-suppression pattern. Vigabatrin was added to the treatment and phenobarbital was reduced and discontinued. Although infrequent, her seizures continued and she was started on clobazam, but it was discontinued after two days because of increased seizure frequency and fever. Ketogenic diet (lipid: nonlipid ratio 3:1) was started at the age of 9 months. There was a significant decrease in seizures within the first week of the diet. Antiepileptic treatments were reduced and discontinued one by one and levetiracetam treatment was started. No treatment-related complications were observed during the 10 months of continued levetiracetam (30 mg/kg/g) and ketogenic diet treatment. Total blood ketone body levels was maintained in the range of 3.6–6.0 mmol/L without any adverse effects. Blood glucose and insulin levels were normal. The latest EEG examination showed disorganized background rhythm and intermittent sharp wave activity in the right anterior temporal sharp waves (Figure 1D) and clinically, she experiences very brief clonic seizures 2–3 times a day.

3. Genetic analysis

DNA from the two patients and their unaffected parents was subjected to whole exome sequencing using a 38 Mb targeted Illumina exome capture, and a mean target coverage of >80x (Broad Institute of MIT and Harvard’s Genomics Platform, Cambridge, MA, USA). Raw sequencing data were then processed and analysed on the RD-Connect Genome-Phenome Analysis Platform (https://platform.rd-connect.eu/). This revealed a reported pathogenic variant in ALG3 (NM_005787.6: c.165C>T; p.Gly55=) that had been previously associated with congenital glycolysis defect type 1d (OMIM 601110). Both twins were homozygous for this variant and each unaffected parent was a heterozygous carrier. This synonymous variant has been shown to result in a 37 bp deletion due to the activation of a cryptic donor splice site leading to a premature termination codon and supporting its pathogenicity. In addition, the patients’ clinical findings were consistent with this disorder [7].

4. Discussion

Excluding our two cases, there are 24 previously reported ALG3-CDG cases (Table 1). Ketogenic diet is an option in the treatment of intractable epilepsies. It can also be used in the treatment of intractable epilepsies in CDG patients [6]. Our patients were the first patients with ALG3-CDG whose intractable epilepsies were controlled by ketogenic diet.

Although all systems can be involved in CDGs, neurological abnormalities are most common. Mental retardation, hypotonia, seizures, microcephaly, facial dysmorphism, skeletal anomalies, and ophthalmologic findings are typical manifestations in ALG3-CDG [2]. Dysmorphic findings such as broad and flattened nasal bridge, high-arched palate, micrognathia, thin upper lip, low-set ears, camptodactyly, and contractures have been reported [1, 8]. Similar dysmorphic features were observed in both of our patients. In addition, hemangioma of the frontal, occipital and lumbosacral regions was observed in both patients. Among the previously reported cases of ALG3-CDG, only one patient had lumbosacral hemangioma [9]. Although hemangioma may be an important clinical feature, we should keep in mind that there may be a lot of candidate genes and single-nucleotide variants responsible for hemangiomas. Nephrocalcinosis detected in our female patient was previously reported only in three female cases [2, 4, 10]. Cerebral anomalies are observed in almost all ALG3-CDG patients [2]. Cerebral atrophy was seen at 6 months of age in the patient with the same variant as our patients [11]. The MRI scans of both of our patients shoved mildly increased subarachnoid space and cavum septum pellucidum.

Severe growth retardation and drug-resistant epileptic encephalopathy are prominent manifestations in these patients [10]. Epilepsy was reported in 14 of 24 patients in the literature. These patients usually have seizures that can be triggered by fever, starting in the first year of life. Generalized tonic clonic, focal, migratory, spasm, and even absence type seizures may occur. Antiepileptic medications such as phenytoin, phenobarbital, valproic acid, vigabatrin, steroids, levetiracetam, and sulthiam have been tried, but seizure control has not been achieved in most of the patients [1–3, 5, 8, 11–15]. Like most of the patients in the literature, our patients also had multiple types of seizures (spasms, tonic, clonic and myoclonic) with burst-suppression pattern on EEG. Seizures were not responded to levetiracetam, phenobarbital, B6, vigabatrin, clobazam.

The ketogenic diet can be used in CDGs as in other intractable epilepsies. However, CDG patients already have a tendency for hypoglycemia due to hyperinsulinism and it should be kept in mind that ketogenic diet may also potentiate this effect [6]. Hyperinsulinemia and/or hypoglycemia were reported only in two patients with ALG3-CDG before [4, 9]. There is no previous information on the use of ketogenic diet in ALG3-CDG. Both of our patients had short, partial response to phenobarbital treatment, but frequency of seizures increased regardless of the treatment. In the first week after the initiation of ketogenic diet, both patients had a reduction over 50% in seizure frequency. We achieved a good seizure control in both patients during a 10 months follow-up with ketogenic diet and levetiracetam. While the female patient has short seizures 2–3 times a day, the male patient did not have any seizures during the follow-up period. Ketogenic diet may be an assessable choice of treatment in ALG3-CDG patients with multiple types of intractable seizures and an EEG pattern of burst-suppression or hypsarrhythmia. The difference between the response rate of the siblings remain unclear.

5. Conclusion

Autosomal recessive mutations in ALG3 cause a rare form of CDG with prominent neurological involvement. We believe that the diagnosis of ALG3-CDG should be considered in patients with intractable epilepsy, growth retardation, microcephaly and visual impairment, especially if hemangioma is present, which may be an important clue. The ketogenic diet can be considered as a good treatment option for intractable epilepsy in ALG3-CDG (CDG-Id) patients.