Novel compound heterozygous ABCA2 variants cause IDPOGSA, a variable phenotypic syndrome with intellectual disability.

The gene for ATP binding cassette subfamily A member 2 (ABCA2) is located at chromosome 9q34.3. Biallelic ABCA2 variants lead to intellectual developmental disorder with poor growth and with or without seizures or ataxia (IDPOGSA). In this study, we identified novel compound heterozygous ABCA2 variants (NM_001606.5:c.[5300-17C>A];[6379C>T]) by whole exome sequencing in a 28-year-old Korean female patient with intellectual disability. These variants included intronic and nonsense variants of paternal and maternal origin, respectively, and are absent from gnomAD. SpliceAI predicted that the intron variant creates a cryptic acceptor site. Reverse transcription-PCR using RNA extracted from a lymphoblastoid cell line of the patient confirmed two aberrant transcripts. Her clinical features are compatible with those of IDPOGSA.

Disease progression in Sanfilippo type B: Case series of Brazilian patients.

Mucopolysaccharidosis type IIIB (MPS IIIB) is caused by deficiency of alpha-N-acetylglucosaminidase, leading to storage of heparan sulphate. The disease is characterized by intellectual disability and hyperactivity, among other neurological and somatic features. Here we studied retrospective data from a total of 19 MPS IIIB patients from Brazil, aiming to evaluate disease progression. Mean age at diagnosis was 7.2 years. Speech delay was one of the first symptoms to be identified, around 2-3 years of age. Behavioral alterations include hyperactivity and aggressiveness, starting around age four. By the end of the first decade, patients lost acquired abilities such as speech and ability to walk. Furthermore, as disease progresses, respiratory, cardiovascular and joint abnormalities were found in more than 50% of the patients, along with organomegaly. Most common cause of death was respiratory problems. The disease progression was characterized in multiple systems, and hopefully these data will help the design of appropriate clinical trials and clinical management guidelines.

X-Linked Levodopa-Responsive Parkinsonism-Epilepsy Syndrome: A Novel PGK1 Mutation and Literature Review.

BACKGROUND: Genetic underpinnings in Parkinson's disease (PD) and parkinsonian syndromes are challenging, and recent discoveries regarding their genetic pathways have led to potential gene-specific treatment trials. CASES: We report 3 X-linked levodopa (l-dopa)-responsive parkinsonism-epilepsy syndrome cases due to a hemizygous variant in the phosphoglycerate kinase 1 (PGK1) gene. The likely pathogenic variant NM_000291.4 (PGK1):c.950G > A;p.(Gly317Asp) was identified in a hemizygous state. LITERATURE REVIEW: Only 8 previous cases have linked this phenotype to PGK1, a gene more commonly associated with hemolytic anemia and myopathy. The unusual association of epilepsy, psychiatric symptoms, action tremor, limb dystonia, cognitive symptoms, and l-dopa-responsive parkinsonism must draw attention to PGK1 mutations, especially because this gene is absent from most commercial hereditary parkinsonism panels. CONCLUSIONS: This report aims to shed light on an overlooked gene that causes hereditary parkinsonian syndromes. Further research regarding genetic pathways in PD may provide a better understanding of its pathophysiology and open possibilities for new disease-modifying trials, such as SNCA, LRRK2, PRKN, PINK1, and DJ-1 genes.