Infantile dystonia-parkinsonism type 2 (PKDYS2) is a rare inherited autosomal recessive movement disorder with onset in infancy. The disease is associated with a mutation in the solute carrier family 18 member A2 gene (SLC18A2). There are reports of trials with dopaminergic drugs and the condition of patients given levodopa almost always worsens and dopamine agonists give varying degrees of benefit to some. Here, we report a PKDYS2 patient with a new variant in the SLC18A2 gene who underwent multiple trials of pharmacotherapy. The abnormalities in development and neurological examination of the case were first noted at the age of 2 months, and after a series of treatment attempts (e.g., with antiepileptics) and diagnostic procedures, the diagnosis of PKDYS2 was determined when whole exome sequencing (WES) at age 6, revealed a homozygous pathologic variant NM_003054.4:c.1107dup, p.(Val370Serfs∗91) in the SLC18A2 gene. The patient then received treatment with multiple dopaminergic drugs (e.g., levodopa, pramipexole, and methylphenidate). The patient with PKDYS2 harbored a new variant in SLC18A2. The phenotype of the patient resembles that of some previously reported patients with PKDYS2. The patient received minor benefits from certain dopaminergic drugs, such as pramipexole, but side effects led to the discontinuation of tested medications.

Aromatic L-amino acid decarboxylase deficiency (AADCD) is a rare, autosomal recessive neurometabolic disorder that leads to a severe combined deficiency of serotonin, dopamine, norepinephrine and epinephrine. Onset is early in life, and key clinical symptoms are hypotonia, movement disorders (oculogyric crisis, dystonia, and hypokinesia), developmental delay, and autonomic symptoms.In this consensus guideline, representatives of the International Working Group on Neurotransmitter Related Disorders (iNTD) and patient representatives evaluated all available evidence for diagnosis and treatment of AADCD and made recommendations using SIGN and GRADE methodology. In the face of limited definitive evidence, we constructed practical recommendations on clinical diagnosis, laboratory diagnosis, imaging and electroencephalograpy, medical treatments and non-medical treatments. Furthermore, we identified topics for further research. We believe this guideline will improve the care for AADCD patients around the world whilst promoting general awareness of this rare disease. Der Aromatische L-Aminosäuren Decarboxylase Mangel (AADCD) ist eine seltene autosomal rezessive neurometabolische Störung, die zu einem schweren kombinierten Mangel an Serotonin, Dopamin, Norepinephrin und Epinephrin führt. Die Symptome setzen in einer frühen Phase des Lebens ein. Die klinischen Hauptsymptome sind muskuläre Hypotonie, Bewegungsstörungen (Okkulogyre Krisen, Dystonie und Hypokinesie), Entwicklungsverzögerung und autonome Symptome. In diesen Konsensus basierten Leitlinien haben Mitglieder der “International Working Group on Neurotransmitter Related Disorders (iNTD)” sowie Patientenvertreter die verfügbare Evidenz für die Diagnose und Behandlung von AADCD ausgewertet und evidenzbasierte Empfehlungen nach den Methoden von SIGN und GRADE formuliert. Stets im Bewusstsein der limitierten Evidenz haben wir praktische Empfehlungen für die klinische Diagnose, Labordiagnose, Bildgebung und EEG, medizinische und nicht medizinische Behandlung formuliert. Des Weiteren haben wir Themen identifiziert, die der weiteren Forschung bedürfen. Wir glauben, dass diese Leitlinie die Behandlung von Patienten mit AADCD verbessert und gleichzeitig das Bewusstsein für diese seltene Erkrankung geschärft wird. The online version of this article (doi:10.1186/s13023-016-0522-z) contains supplementary material, which is available to authorized users. La deficiencia de la descarboxilasa de aminoácidos aromáticos (AADCD) es una enfermedad neurometabólica minoritaria de herencia autosómica recesiva que causa un defecto grave de dopamina, serotonina, epinefrina y norepinefrina. El inicio de la enfermedad es precoz, y sus síntomas principales incluyen hipotonía, trastornos del movimiento (crisis oculógiras, distonía e hipocinesia), retraso del desarrollo y signos disautonómicos. En esta guía de consenso han participado representantes del grupo de trabajo internacional sobre trastornos de la neurotransmisión (iNTD) y representantes de las asociaciones de pacientes, que han evaluado todas las evidencias existentes en relación al diagnóstico y tratamiento de la AADCD. Las recomnedaciones se han realizado siguiendo la metodología SIGN y GRADE. A pesar de los bajos niveles de evidencia existentes, se han podido establecer recomendaciones prácticas y que pueden ser muy útiles sobre el diagnóstico clínico y de laboratorio, las pruebas de neuroimagen y electroencefalográficas y sobre tratamientos tanto médicos como de soporte. Se han identificado además temas que pueden ser interesantes a desarrollar en el campo de la investigación de la AADCD. En conclusión, pensamos que esta guía aumentará la calidad en los cuidados de los pacientes con AADCD en todo el mundo, y que aumentará el conocimiento de esta rara enfermedad. The online version of this article (doi:10.1186/s13023-016-0522-z) contains supplementary material, which is available to authorized users.

The human dopamine transporter (hDAT) belongs to the solute carrier 6 (SLC6) gene family. Point mutations in hDAT (SLC6A3) have been linked to a syndrome of dopamine transporter deficiency or infantile dystonia/parkinsonism. The mutations impair DAT folding, causing retention of variant DATs in the endoplasmic reticulum and subsequently impair transport activity. The folding trajectory of DAT itself is not understood, though many insights have been gained from studies of folding-deficient mutants of the closely related serotonin transporter (SERT); i.e. their functional rescue by pharmacochaperoning with (nor)ibogaine or heat-shock protein inhibitors. We recently provided a proof-of-principle that folding-deficits in DAT are amenable to rescue in vitro and in vivo. As a model we used the Drosophila melanogaster DAT mutant dDAT-G108Q, which phenocopies the fumin/sleepless DAT-knockout. Treatment with noribogaine and/or HSP70 inhibitor pifithrin-μ restored folding of, and dopamine transport by, dDAT-G108Q, its axonal delivery and normal sleep time in mutant flies. The possibility of functional rescue of misfolded DATs in living flies by pharmacochaperoning grants new therapeutic prospects in the remedy of folding diseases, not only in hDAT, but also in other SLC6 transporters, in particular mutants of the creatine transporter-1, which give rise to X-linked mental retardation.

Folding-defective mutants of the human dopamine transporter (DAT) cause a syndrome of infantile dystonia/parkinsonism. Here, we provide a proof-of-principle that the folding deficit is amenable to correction in vivo by two means, the cognate DAT ligand noribogaine and the HSP70 inhibitor, pifithrin-μ. We examined the Drosophila melanogaster (d) mutant dDAT-G108Q, which leads to a sleepless phenotype in flies harboring this mutation. Molecular dynamics simulations suggested an unstable structure of dDAT-G108Q consistent with a folding defect. This conjecture was verified; heterologously expressed dDAT-G108Q and the human (h) equivalent hDAT-G140Q were retained in the endoplasmic reticulum in a complex with endogenous folding sensors (calnexin and HSP70-1A). Incubation of the cells with noribogaine (a DAT ligand selective for the inward-facing state) and/or pifithrin-μ (an HSP70 inhibitor) restored folding of, and hence dopamine transport by, dDAT-G108Q and hDAT-G140Q. The mutated versions of DAT were confined to the cell bodies of the dopaminergic neurons in the fly brain and failed to reach the axonal compartments. Axonal delivery was restored, and sleep time was increased to normal length (from 300 to 1000 min/day) if the dDAT-G108Q-expressing flies were treated with noribogaine and/or pifithrin-μ. Rescuing misfolded versions of DAT by pharmacochaperoning is of therapeutic interest; it may provide opportunities to remedy disorders arising from folding-defective mutants of human DAT and of other related SLC6 transporters.