Hypermanganesemia with Dystonia Type 2: A Potentially Treatable Neurodegenerative Disorder: A Case Series in a Tertiary University Hospital

Importance: Hypermanganesemia with dystonia type 2 is a rare autosomal recessive neurodegenerative disorder characterized by the loss of previously acquired milestones, dystonia, parkinsonian features, a high serum manganese level, and characteristic neuroimaging findings such as bilateral and symmetrically increased T1 and decreased T2/fluid-attenuated inversion recovery signal intensity in the basal ganglia. This condition is secondary to a mutation in the SLC39A14 gene. Objective: To present a series of three cases of hypermanganesemia with dystonia type 2, which was genetically confirmed secondary to a mutation in the SLC39A14 gene, and to describe the treatment and clinical course in these cases. Design: A retrospective case series. Setting: University, Tertiary hospital. Participants: Three unrelated pediatric patients with hypermanganesemia with dystonia type 2, genetically confirmed to be secondary to a mutation in the SLC39A14 gene. Exposures: Chelation therapy using calcium disodium edetate. Main outcome(s) and measure(s): The response to chelation therapy based on clinical improvements in motor and cognition developments. Results: All three patients were started on chelation therapy using calcium disodium edetate, and two of them showed an improvement in their clinical course. The chelation therapy could alter the course of the disease and prevent deterioration in the clinical setting. Conclusions and Relevance: Early diagnosis and intervention with chelating agents, such as calcium disodium edetate, will help change the outcome in patients with hypermanganesemia with dystonia type 2. This finding highlights the importance of early diagnosis and treatment in improving the outcomes of patients with treatable neurodegenerative disorders

Patient F2 (P1) MRI, age 3 years 3 months (A-D).

<p>Coronal T2-weighted (A), axial T2-weighted (B), axial diffusion (C), axial FLAIR (D) showing cerebellar atrophy (arrows) with widening of cerebellar folia (A), T2 normal signal intensity (arrows) of <i>globus </i><i>pallidus</i> (B), highlighted subtle iron deposition at globus pallidi (arrows) as reduction in signal intensity (C), and high signal intensity (arrows) at cerebral white matter (D). Patient F2 (P2) MRI, age 1 year 3 months (E-H)). Coronal T2-weighted (E), axialT2-weighted (F), axial diffusion (G), axial FLAIR (H) showing mild cerebellar atrophy (arrows) with mild widening of cerebellar folia (E), normal signal intensity (arrows) of <i>globus </i><i>pallidus</i> (F and G), and high signal intensity (arrows) at cerebral white matter (H).</p

Genotype-phenotype correlation.

<p>Graphic representation of the evolution exponential tendency curves of the functional disability (red curve and red squares) and of the age at onset of ataxia (blue curve and blue squares) which both seem to depend on the nature of the mutation. Each number in X axis corresponds to one patient. Below this axis are indicated the codes of patients (from Families 1 to 6) and the corresponding mutation. Y axis corresponds to the age per years. Two groups are identified (dashed ellipses) depending on the age at onset of ataxia. The first one encompasses the patients with ataxia manifesting at or before 15 months of age, and the second one, patients with an onset between 3 and 6 years. The age when becoming wheelchair-bound (red squares) and the disease duration (green triangles) are most prominent clusters in the second group. Abbreviations: wb = wheelchair-bound. Expon = exponential.</p

Patient F5 (P1) MRI, age 4 years 2 months (A-D), and 7 years 6 months (E-H).

<p>Sagittal T1-weighted (A and E), coronal T2-weighted (B and F), axial T2-weighted (C and G) and axial diffusion (D and H) sequences showing mild cerebellar cortical atrophy with mildly prominent folia (arrows in C). There is also simple corpus callosum (arrows in E). (F) Coronal T2-weighted reveals progressive cerebellar cortical atrophy and gliosis, with widening of folia and increased signal in the residual cerebellar cortex (arrow). Axial T2-weighted (G), and axial diffusion (H) sequences highlight iron deposition as reduction in signal intensity in the globus pallidi (arrows).</p

Genetics findings.

<p>Pedigrees (Ped) of the six Saudi Arabian families (F1-6) are represented in the same order as in the tables and in Figure 7. Patients were also numbered according to the Tables. Haplotypes were reconstructed manually (Family F4 was not subjected to genotyping) and chromatograms of each identified mutation are shown, except Family F4 which had direct sequencing in a private company. The segregation of the mutation, when possible, was shown for each pedigree with the corresponding symbols (“+”= wild type and “-“= mutated).</p

Patient F6 (P3) MRI, age 17 years 5 months.

<p>Axial T2-weighted (A), axial gradient (B and C), sagittal T1-weighted (D) and coronal fluid-attenuated inversion recovery (FLAIR, E) sequences highlight iron deposition as reduction in signal intensity in the globus pallidi (arrows in A and B) and <i>substantia </i><i>nigra</i> (arrow in C). There is also cerebellar cortical atrophy with increased CSF spaces around the cerebellum (arrows in D and E).</p

Patient F1 (P1) MRI, age 3 years 1 month (A-D), and 4 years 2 months (E-H).

<p>There is increased CSF space around the cerebellum (arrows in A and E) associated with cerebellar cortical atrophy and gliosis, with widening of folia and increased signal in the residual cerebellar cortex (arrows in B and F). Axial T2-weighted (C and G) and axial diffusion (D and H) highlight iron deposition as reduction in signal intensity in the <i>globus </i><i>pallidi</i> in only the later T2-weighted sequence (G), but in both diffusion sequences (D and H).</p

Accelerating Novel Candidate Gene Discovery in Neurogenetic Disorders via Whole-Exome Sequencing of Prescreened Multiplex Consanguineous Families

Our knowledge of disease genes in neurological disorders is incomplete. With the aim of closing this gap, we performed whole-exome sequencing on 143 multiplex consanguineous families in whom known disease genes had been excluded by autozygosity mapping and candidate gene analysis. This prescreening step led to the identification of 69 recessive genes not previously associated with disease, of which 33 are here described (SPDL1, TUBA3E, INO80, NID1, TSEN15, DMBX1, CLHC1, C12orf4, WDR93, ST7, MATN4, SEC24D, PCDHB4, PTPN23, TAF6, TBCK, FAM177A1, KIAA1109, MTSS1L, XIRP1, KCTD3, CHAF1B, ARV1, ISCA2, PTRH2, GEMIN4, MYOCD, PDPR, DPH1, NUP107, TMEM92, EPB41L4A, and FAM120AOS). We also encountered instances in which the phenotype departed significantly from the established clinical presentation of a known disease gene. Overall, a likely causal mutation was identified in >73% of our cases. This study contributes to the global effort toward a full compendium of disease genes affecting brain function