Case#:Patient 7, male, 5 years old

DiseaseAssertion:Neonatal/Infantile Epileptic Encephalopathy (NIEE)

FamilyInfo:The family is French/Chinese

ParentalGenotype:The variant was inherited from Patient 7's asymptomatic mother.

CasePresentingHPOs:HP:0010864, HP:0012758, HP:0000729, HP:0007359, HP:0002069, HP:0032794, HP:0001250, HP:0000252.

CaseHPOFreeText:Patient 7 presents with severe intellectual disability, developmental slowdown, and various seizure types. Patient 7 has Autistic Spectrum Disorder (ASD) and microcephaly.

Patient History

@ 12 months - Patient 7 presented with seizures.

Patient 7 developed additional seizure types including: focal seizures with/without generalization, generalized tonic/clonic/tonic-clonic seizures, myoclonic seizures, and hypomotor seizures.

Patient 7 was on two antiepileptic drugs at most recent followup visit which reduced seizure frequency by >50%.

CaseNotHPOs:Not provided

CaseNotHPOFreeText:Not provided

CasePreviousTesting:The authors selected a cohort of 31 patients with seizure cryptogenic Neonatal/Infantile Epileptic Encephalopathy (NIEE) and seizure onset before 24 months.

Exclusion criteria included: (1) Patients with a definite history of brain insult, malformation of cortical development, neurocutaneous and syndromal disorders, and confirmed or highly suspected neurometabolic disorders based on clinical and biochemical markers. (2) Patients with Dravet syndrome and epilepsy at infancy with migrating focal seizure were also excluded because the majority of variants are detected in the SCN1A (>85%) and KCNT1 (approximately 50%) genes.

Formal neuropsychological testing or best clinical assessment was used to classify patient development or intelligence.

PreviouslyPublished:Not previously published

GenotypingMethod:Whole Exome Sequencing (WES) variant results were filtered in a panel of 430 epilepsy-associated genes. After selection of variants from the 430-gene panel, the synonymous variants, variants with variant frequency <10%, and variants with allele frequency >1% were removed.

Gene:SLC9A6

Variant:Hemizygous splice site NM_001042537.1 c. 794-2A>G was assessed by the authors to be likely pathogenic.

HGVS:Not provided

ClinVarID:Not found

CAID:CA414750320

gnomAD:Not found

MultipleGeneVariants:Not provided

Case: Patient 1, female, 2 years old

DiseaseAssertion: Rett Syndrome

FamilyInfo: DeNovo. Patient 1 was the second child of a nonconsanguineous Chinese couple. Patient 1 was born at full term with a birth weight of 3.83 kg.

ParentalGenotype(s):Not provided

CasePresentingHPOs:HP:0011344, HP:0001250, HP:0001252, HP:0000252, HP:0000748, HP:0003763, HP:0005469, HP:0000486, HP:0012171.

CaseHPOFreeRext:Patient 1 presents with severe global developmental delay, epilepsy, and hypotonia. The Patient History contains all of Patient 1's phenotypes along with the progression of her condition.

Patient History

@ 3 months - Patient 1 had microcephaly (head circumference was less than 3rd percentile with a body weight and body height at 75th percentile). Patient 1 had hypotonia.

Patient 1 was given a metabolic screening, a muscle enzyme, and a brain tomography with normal results.

@ 6 months - Patient 1 had microcephaly, flat occiput, right divergent squint, and hypotonia. No syndromal diagnosis could be ascertained at that time.

@ 2 years - Patient 1 had epilepsy.

Patient 1 had severe global development delay.

Patient 1 was given an EEG which showed nonspecific background slowing, but no epileptiform abnormalities. Patient 1 was also given a brain MRI which showed mild thinning of corpus callosum without major structural defect. Patient 1 had no developmental regression but she developed stereotypical hand movements, bruxism, and occasional outburst of laughter.

Based on these phenotypes, Angelman/Rett Syndrome was suspected.

CaseNOTHPOs: HP:0002353.

CaseNOTHPOFreeText: Patient 1 was given an EEG which detected no epileptic abnormalites.

CasePreviousTesting: Genetic investigations (including methylation-specific multiplex ligation-dependent probe amplification (MS-MLLPA)) was conducted for Angelman Syndrome, UBE3A gene, MECP gene, and array CGH. These studies were negative. A FOXG1 related disease was suspected

PreviouslyPublished:Not previously published

GenotypingMethod: A FOXG1 gene test showed a de novo frameshift pathogenic mutation FOXG1 {NM_005249.3} c. 396_397ins26; FOXG1{NP_005240.3} :(p. Gly133TRPfs*68) which confirmed the diagnosis of a FOXG1 related congenital variant of Rett Syndrome.

Gene:FOXG1

Variant: (NM_005249.3) c. 396_397ins26 (p. Gly133Trpfs*68)

HGVS:Not provided

ClinVarID:Not found

CAID:Not found

gnomAD:Not found

Case:Patient 1, female, 11 years old

DiseaseAssertion:Rett Syndrome - Atypical Variant

FamilyInfo:De Novo. Patient 1's parents were healthy. When Patient 1 was clinically examined, the head circumferences of her mother and father were 53 cm (P25) and 59 cm (P90), respectively. The parents had normal weight.

ParentalGenotype:Both parents were sequenced for Patient 1's mutation, and the deletion was not detected.

CasePresentingHPOs:HP:0001249, HP:0001513, HP:0001626, HP:0000256, HP:0010465, HP:0012758, HP:0000750, HP:0012433, HP:0002591, HP:0001250, HP:0020174, HP:0000316, HP:0000336, HP:0000431, HP:0000377, HP:0000470, HP:0001156, HP:0001500.

CaseHPOFreeText:

Patient history

@ birth - Patient 1 was born at 38 weeks of gestation after an uncomplicated pregnancy. Her weight was 3,390 g (P69), height 51 cm (P60), and her head circumference was 36 cm (P90).

@ 6 months - Patient 1 experienced developmental delay.

@ 9 months - Patient 1 sat without support.

@ 2 years - Patient 1 began to walk.

@ later on - Patient 1 presented with speech delay and behavioral disturbances. The behavioral disturbances were reduced by the drug risperidone.

@ early childhood - Patient 1 has been obese and appeared to display hyperphagia.

@ 8 years - Patient 1 developed precocious puberty.

@ 10 years - Patient 1 had her first epileptic seizure. Treatment with lamotrigine prevented further seizures. The seizures later became refractory to this treatment.

@ 10 years - Patient 1 presented with a height of 160 cm (P>97) and a head circumference of 59 cm (P>97). She had hypertelorism and prominent eyebrows. Her nasal bridge was broad and auricles were fleshy. In addition, Patient 1's neck was short and the fingers were short and wide.

Patient 1 has an intellectual disability, metabolic syndrome, and macrocephaly.

CaseNotHPOs:HP:0002540.

CaseNotHPOFreeText:Patient 1 sat without support at 9 months old. She walked at 2 years.

CasePreviousTesting:Patient 1 was given a conventional cytogenetic analysis. The chromosomal analyses (46,XX) and array CGH results (BlueGnome CytoChip ISCA 4×180K v1.0; Agilent Human Genome CGH Microarray 180K) were normal. Patient 1 was also given a methylation-specific MLPA to exclude a Temple syndrome, which is also characterized by weight gain and precocious puberty. In addition, Prader-Willi syndrome was ruled out by methylation testing. This syndrome is another imprinting disease causing obesity and intellectual disability.

PreviouslyPublished:Not previously published

GenotypingMethod:Whole-exome sequencing analysis of the entire exome was conducted for Patient 1. Whole-genome sequencing showed heterozygosity in Patient 1, which was confirmed by Sanger sequencing. Macrocephalic syndrome genes including PTEN, NSD1, NFIX, SETBP1, RAI1, and PHF6 were analyzed, and no additional variants of interest (pathogenic, likely pathogenic, or variants of uncertain significance) were observed.

Gene:MECP2

Variant:c. 1162_1172del (p. Pro388*), heterozygosity, frameshift.

HGVS:NM_004992.3

ClinVarID:Not found

CAID:CA1139667881

gnomAD:Not found

MultipleGeneVariants:Not provided

Case:Patient 2, female, 2.5 years old

DiseaseAssertion:CDKL5 Disorder

FamilyInfo:De Novo with an unremarkable family history.

ParentalGenotype:Not provided

CasePresentingHPOs:HP:0032792, HP:0007359, HP:0011154, HP:0002194, HP:0010862, HP:0000750, HP:0012434, HP:0000710, HP:0100023, HP:0000252, HP:0009062, HP:0010845, HP:0020174, HP:0010841.

CaseHPOFreeText:

Patient history

@ 2 months to 2.5 years - Patient 2 experienced tonic and focal seizures with autonomic symptoms.

@ 2 years - Patient 2 was diagnosed with CDKL5 disorder.

Patient 2 had severe delayed gross motor development, severe delayed fine motor development, severe delayed language development and delayed social development. Patient 2 had hyperoral and hand flapping stereotypies. She also had microcephaly (< 2 SD) and axial hypotonia.

Patient 2 was given a brain EEG which detected Delta slowing of the background followed by generalized attenuation during seizures and multifocal interictal epileptiform abnormalities.

@ 2.5 years - Patient 2 experienced seizures in clusters.

Treatments

Antiepleptic treatments included:Phenobarbital, Topirimate, Clobazam, Valproate, Keppra, Vitamin B6, Phenytoin, Lamotrigine, Nitrazepam, Oxcarbazepine, Mirtazipine, KCI, Levetiracetam, ant ketogenic diet.

Patient 2 was also treated with Carnitine. Patient 2's seizures seem to have changed in type over time but continued.

Other testing

Tests were conducted on Patient 2 to obtain data in the following areas: NBS, lactate, lipoprotein profile, plasma and urine amino acids, urine organic acids, acylcarnitine profile, total and free serum carnitine levels, plasma ammonia, total plasma homocysteine, serum CK, liver enzymes, urine alpha-AASA, creatine, biotinidase, VLCFA, Batten disease screen, CSF analysis (amino acids, lactate, glucose, protein, cell count, neurotransmitters), MRI-brain with spectroscopy, and karyotype.

CaseNotHPOs:Not provided

CaseNotHPOFreeText:Not provided

CasePreviousTesting:Patient 2 was given a gene sequence test for the genes SCNIA and MECP2. No gene mutation was found for these two genes.

PreviouslyPublished:Not previously published

GenotypingMethod:Patient 2 was given a CDKL5 gene sequence test. The test detected a mutation in the CDKL5 gene.

Gene:CDKL5

Variant:c. 2480_2486dupCAGATCT. frameshift

The authors state that CDKL5 gene sequencing detected a de novo duplication in exon 17, c. 2480_2486dupCAGATCT, resulting in a frameshift (Boston University School of Medicine, Center for Human Genetics, Boston, MA). This is a novel change that has not been reported before in ExAC. Only pathogenic point mutations in exon 17 have previously been reported. In a patient with a previously reported frameshift mutation in exon 18, a truncated CDKL5 transcript was detected. A truncated protein would lack the C-terminus and would not localize correctly in the cell, as demonstrated in vitro. Accordingly, any reading frame altering mutations proximal to exon 18 are null-variants. Therefore, this mutation is classified as pathogenic according to ACMG criteria.

HGVS:Not provided

ClinVarID:547188

NM_001323289.2 (CDKL5): c. 2480_2486dup (p. Gln830fs)

Allele ID: 538303

CAID:Not found

gnomAD:Not found

MultipleGeneVariants:Not provided