1. Forging a Path to Diagnosis of AADC Deficiency
Raising Clinical Awareness
Moderator
Panelist
Keith Hyland, PhD
Executive Vice President
Director
Neurochemistry Diagnostic Unit
Medical Neurogenetics Laboratories
Atlanta, Georgia
Irina Anselm, MD
Assistant Professor of Neurology
Harvard Medical School
Child Neurologist
Boston Children's Hospital
Boston, Massachusetts
AADC = aromatic L-amino acid decarboxylase

2. Aromatic L-Amino Acid Decarboxylase
Aromatic L-amino acid decarboxylase (AADC)
AADC deficiency is an autosomal recessive disorder of neurotransmitter synthesis[a]
Ultra rare disease that affects brain metabolism[b]
First reported in 1992
~117 patients diagnosed worldwide[c]
Prevalence (predicted birthrates)[d]:
1 in 90,000 in United States
1 in 118,000 in Europe
1 in 182,000 in Japan
Brun L, Ngu LH, Keng WT, et al. Clinical and biochemical features of aromatic L-amino acid decarboxylase deficiency. Neurology. 2010;75:64-71.
Hyland K, Surtees RA, Rodeck C, et al. Aromatic L-amino acid decarboxylase deficiency: clinical features, diagnosis, and treatment of a new inborn error of neurotransmitter amine synthesis. Neurology. 1992;42:
Wassenberg T, Molero-Luis M, Jeltsch K, et al. Consensus guideline for the diagnosis and treatment of aromatic l-amino acid decarboxylase (AADC) deficiency. Orphanet J Rare Dis. 2017;12:12.
a. Brun L, et al. Neurology. 2010;75:64-71; b. Hyland K, et al. Neurology. 1992;42: ;
c. Wassenberg T, et al. Orphanet J Rare Dis. 2017;12:12; d. Pre-published data courtesy of Keith Hyland, PhD.

3. What Is AADC? AADC is a protein that functions as an enzyme
Required for synthesis of several neurotransmitters
AADC aids in the production of:
Dopamine
Serotonin
Norepinephrine
Epinephrine
Melatonin
Effect of AADC Deficiency in Neurotransmitter Synthesis
Tyrosine
hydroxylase
L-Dopa
Tryptophan
5-HTP
Dopamine
Serotonin
AADC
Norepinephrine
Epinephrine
Melatonin
Shih DF, Hsiao CD, Min MY, et al. Aromatic L-Amino Acid Decarboxylase (AADC) Is Crucial for Brain Development and Motor Functions. PLoS One. 2013;8:e71741.
Pappan KL, Kennedy AD, Magoulas PL, et al. Clinical Metabolomics to Segregate Aromatic Amino Acid Decarboxylase Deficiency From Drug-Induced Metabolite Elevations. Pediatr Neurol. 2017;75:66-72.
Shih DF, et al. PLoS One. 2013;8:e71741; Pappan KL, et al. Pediatr Neurol. 2017;75:66-72.

4. Enzyme Structure
L-Dopa
AADC
© Medscape, LLC
S250F
F309L
A91V
A275T
G102S
G123R
S147R
AADC deficiency in humans occurs as a result of genetic changes
These changes alter the structure of the enzyme
Can no longer function in the production of neurotransmitters
Over 80 pathogenic variants identified
Chang YT, Sharma R, Marsh JL, et al. Levodopa-responsive aromatic L-amino acid decarboxylase deficiency. Ann Neurol. 2004;55:
Chang YT, et al. Ann Neurol. 2004;55:

5. Role of Neurotransmitters
Exocytosis
Tyrosine
Dopamine
L-DOPA
Synaptic cleft
AADC
Postsynaptic neuron
Presynaptic terminal
Postsynaptic receptor and ionic channel
Vesicle containing neurotransmitter
Transporter
Tyrosine hydroxylase
Monoamine oxidase (MAO)
COMT
MAO COMT
© Medscape, LLC
Vesicular Transporter
Liver
Rilstone JJ, Alkhater RA, Minassian BA. Brain dopamine-serotonin vesicular transport disease and its treatment. N Engl J Med. 2013;368:
Rilstone JJ, et al. N Engl J Med. 2013;368:

6. Developmental Delay Symptom onset occurs during first months of life
Not diagnosed until much later in life
Key symptom is developmental delay
Do not reach any motor milestones
Motor delay
Speech delay
Cognitive delay
Later, some milestones may be reached
Majority will remain very delayed for the rest of their lives
Dopamine and serotonin are necessary for normal nervous system function
Wassenberg T, et al. Orphanet J Rare Dis. 2017;12:12
Genetics Home Reference (GHR) Website. Aromatic l-amino acid decarboxylase deficiency. May Available at:  Accessed January 9, 2019.
Hwu WL, et al. [Published online August 31, 2017]. J Inherit Metab Dis Rep. doi: /8904_2017_54.
Wassenberg T, et al. Orphanet J Rare Dis. 2017;12:12; GHR Website. AADC Deficiency 2008.

7. Signs in AADC Deficiency
Axial hypotonia
Truncal
Limb hypertonia
Dystonia
Hypokinesia
Bradykinesia
Tremor
Athetosis
Myoclonic jerks
Blepharospasm
Oculogyric crises
Clue to diagnosis
Can persist for several hours and recur every 2 to 5 days
Feeding/swallowing problems
Wassenberg T, et al. Orphanet J Rare Dis. 2017
Genetics Home Reference (GHR) Website. Aromatic l-amino acid decarboxylase deficiency. May Available at:  Accessed January 9, 2019.
Hwu WL, Muramatsu S, Tseng SH, et al. Gene therapy for aromatic L-amino acid decarboxylase deficiency. Sci Transl Med. 2012;4:134ra61.
Wassenberg T, et al. Orphanet J Rare Dis
GHR Website. AADC Deficiency 2008.
Hwu WL, et al. Sci Transl Med. 2012;4:134ra61.

8. Patient Video 1 Age: 22 years
Diagnosed with AADC deficiency at 5 months by CSF analysis.
Symptoms:
Developed symptoms immediately after birth
Tremor in arm and legs
Rigidity
Oculogyric crisis
Other conditions:
Gastrointestinal dysmotility
Restrictive lung disease caused by severe scoliosis
She developed symptoms immediately after birth (hypothermia, hypotonia, problems with breastfeeding). She developed oculogyric crises at several months, as well as dystonia and hypokinesia. She had normal brain MRI and non-specific EEG.
Diagnosed with AADC deficiency at 5 months by CSF analysis.
Over the years she continued to have oculogyric crises, severe movement disorder and multiple medical problems, including gastro intestinal dysmotility. She required tracheostonmy (seen on the video) secondary to restrictive lung disease caused by severe scoliosis.
Video courtesy of Irina Anselm, MD.

9. Lee HF, et al. Eur J Paediatr Neurol. 2009;13:135-140
Oculogyric Crisis
Rare movement disorder characterized by paroxysmal, conjugate, tonic, usually upwards, deviation of the eyes
May last for minutes, but frequently last for hours
These spasms may mimic other conditions:
Brain stem encephalitis
Seizures
Drug induced
Lee HF, et al. Eur J Paediatr Neurol. 2009;13:
Normal EEG and/or failure to respond to antiepileptic medications are important clues to distinguish oculogyric crises from seizures
EEG = electroencephalography
Slow EJ, Lang AE. Oculogyric crises: A review of phenomenology, etiology, pathogenesis, and treatment. Mov Disord. 2017;32:
Lee HF, Tsai CR, Chi CS, et al. Aromatic l-amino acid decarboxylase deficiency in Taiwan. Eur J Paediatr Neurol. 2009;13:
Slow EJ, et al. Mov Disord. 2017;32: ; Lee HF, et al. Eur J Paediatr Neurol. 2009;13:

10. Monoamine Metabolic Pathways
Melatonin
AADC
Epinephrine
Allen GF, Land JM, Heales SJ. A new perspective on the treatment of aromatic L-amino acid decarboxylase deficiency. Mol Genet Metab. 2009;97:6-14.
AADC
Allen GF, et al. Mol Genet Metab. 2009;97:6-14.
Hare EE, et al. BMC Evolutionary Biology. 2004;4:1-20.

11. Symptoms in AADC Deficiency
Autonomic dysfunction/instability
Ptosis
Excessive sweating
Nasal congestion
Arterial hypotension
Temperature instability
Mood instability
Irritability
Sleep disturbance
Insomnia and/or hypersomnia
Changes in melatonin levels
Wassenberg T, et al. Orphanet J Rare Dis
Wassenberg T, et al. Orphanet J Rare Dis. 2017;12:12.

12. Recognition and Diagnosis
Most patients develop symptoms very early
Mean age of diagnosis 3.5 years
Some diagnosed later than that
Some are not diagnosed at all
Uncertainty about child's condition can be very distressing
Wassenberg T, et al. Orphanet J Rare Dis
Wassenberg T, et al. Orphanet J Rare Dis. 2017;12:12.

13. Delay in Diagnosis Lack of awareness of AADC deficiency
Initial suspected diagnoses
Epilepsy
Cerebral palsy
Hyperekplexia
Congenital myasthenia
Mitochondrial disorder
Swoboda KJ, Saul JP, McKenna CE, et al. Aromatic L-amino acid decarboxylase deficiency: overview of clinical features and outcomes. Ann Neurol. 2003;54 Suppl 6:S49-55.
Swoboda KJ, et al. Ann Neurol. 2003;54(Suppl 6):S49-S55.

14. Diagnostic Testing Useful diagnostic tests
Lumbar puncture
Analysis of metabolites of neurotransmitters in CSF
Special arrangements to send to lab
Genetic testing with next-generation sequencing
Whole exome sequencing
Measurement of AADC enzyme activity in plasma
Diagnostic test not useful for diagnosis
Catecholamine metabolites in urine
MRI
EEG
CSF = cerebrospinal fluid
MRI = magnetic resonance imaging
Wassenberg T, et al. Orphanet J Rare Dis
Wassenberg T, et al. Orphanet J Rare Dis. 2017;12:12.

15. Blood Diagnostic Test AADC
In the absence of AADC, the substrate L- dopa accumulates and gets converted to 3-O- methyldopa (3-OMD)
3-OMD then accumulates to high levels in blood and acts as a biomarker for diagnosing AADC deficiency
Tyrosine
hydroxylase
L-Dopa
Tryptophan
5-HTP
Dopamine
Serotonin
AADC
Norepinephrine
Epinephrine
Melatonin
3-OMD
3-OMD = 3-O-methyldopa
Wassenberg T, et al. Orphanet J Rare Dis
Wassenberg T, et al. Orphanet J Rare Dis. 2017;12:12.

16. Blood Diagnostic Test (cont)
Test uses mass spectrometry
Allows for mass screening in target populations
Incorporation of this simple blood test into newborn screening programs will improve diagnostic delay
Figure courtesy of Dr Keith Hyland.

17. Treatment Options First line treatment:
Dopamine agonists
Pramipexole
Ropinerol
Rotigotine
MAO inhibitors
Tranylcypromine
Selegiline
Phenelzine
Pyridoxine (vitamin B6)
Additional symptomatic medications:
Anticholinergic
Benzodiazepines
Sleep aids
Current medications cannot improve the developmental trajectory of these children with AADC deficiency
MAO = monoamine oxidase
Wassenberg
Brun L, et al. Neurology. 2010;75:64-71
Wassenberg T, et al. Orphanet J Rare Dis. 2017;12:12; Brun L, et al. Neurology. 2010;75:64-71.

18. Gene Therapy for AADC Deficiency
Mutation of the dopa decarboxylase (DDC) gene causes AADC deficiency
Gene therapy
Directly injects the normal non-mutated DDC gene, that codes for AADC, into specific regions of the brain
Restores AADC function and dopamine expression in the putamen
Improves motor function and development
L-Dopa
Dopamine
AADC
Dopamine Synthesis
Putamen
© Medscape, LLC
DDC = dopa carboxylase
Chien Y, Lee N, Tseng S, et al. Gene Therapy with AGIL‐AADC in Children with AADC Deficiency Leads to De Novo Dopamine Production and Sustained Improvement in Motor Milestones Over 5 Years. Child Neurology Society 47th Annual Meeting; October 15-18, 2018; Chicago, IL. Presentation PL1-1.
Chien Y, et al. CNS Presentation PL1-1.

19. Gene Therapy Clinical Trial Study Design
Eighteen patients with severe AADC deficiency
10 girls, 8 boys
Ages ranged from 21 months to 8.5 years at the time of administration
None had reached any milestones, including head control, at the time of enrollment
All received AGIL-AADC:
Vector genomes were administered as bilateral intraputaminal stereotactic infusions during a single operative session
Chien Y, Lee N, Tseng S, et al. Gene Therapy with AGIL‐AADC in Children with AADC Deficiency Leads to De Novo Dopamine Production and Sustained Improvement in Motor Milestones Over 5 Years. Child Neurology Society 47th Annual Meeting; October 15-18, 2018; Chicago, IL. Presentation PL1-1.
Chien Y, et al. CNS Presentation PL1-1.

20. Gene Therapy Clinical Trial Results
At interim analysis, all patients are 2 years post-gene therapy
7 are 5 years post–gene therapy
One patient died at 11 months post–gene therapy
Death was unrelated to AGIL-AADC administration
Two years after AGIL-AADC administration:
8/18 (44%) patients gained full head control (P <.0001)
6/18 (33%) could sit unassisted (P <.0001)
3/18 (17%) could stand with support (P =.0050)
Chien Y, Lee N, Tseng S, et al. Gene Therapy with AGIL‐AADC in Children with AADC Deficiency Leads to De Novo Dopamine Production and Sustained Improvement in Motor Milestones Over 5 Years. Child Neurology Society 47th Annual Meeting; October 15-18, 2018; Chicago, IL. Presentation PL1-1.
Chien Y, et al. CNS Presentation PL1-1.

21. Gene Therapy Clinical Trial Results (cont)
Beyond 2 years, half of all patients have achieved a milestone
7/18 (39%) sit unassisted
5/18 (28%) stand with support
Of these 5 patients:
2 gained locomotor activity with a wheeled walker
1 is learning to walk without assistance
Overall safety data is good
Chien Y, Lee N, Tseng S, et al. Gene Therapy with AGIL‐AADC in Children with AADC Deficiency Leads to De Novo Dopamine Production and Sustained Improvement in Motor Milestones Over 5 Years. Child Neurology Society 47th Annual Meeting; October 15-18, 2018; Chicago, IL. Presentation PL1-1.
Chien Y, et al. CNS Presentation PL1-1.

22. Patient Video 2 AADC-Deficient Patient Baseline Age: 2 years 5 months
Severe motor delay and hypertonia
2 Years Post-Gene Therapy
Able to crawl, stand and make few steps with support
AAV2 gene therapy in children with aromatic L-amino acid decarboxylase deficiency: Part 1
Reprinted from Publication title, Efficacy and Reprinted from The Lancet Child & Adolescent Healthsafety of AAV2 gene therapy in children with aromatic L-amino acid decarboxylase deficiency: an open-label, phase 1/2 trial, with permission from Elsevier.

23. Conclusions
Gene therapy will transform the outcome of AADC-deficient children and their families
There is a need for improved education of healthcare providers to allow better recognition of this disorder
Better recognition will lead to earlier diagnosis, treatment and improved outcomes.
Gene therapy will also move AADC deficiency into the "treatable" disorder category
In the near future, testing for this disorder may be incorporated into newborn screening programs throughout the world
Allowing for diagnosis and commencement of treatment soon after birth

24. Thank you for participating in this activity.
Please proceed to answer the post-activity assessment questions and receive credit. Please also take a moment to complete the program evaluation.