LSD Part 3BLSD Part 3BSome examples of treatable Some examples of treatable

pediatric and adultpediatric and adult onsetonsetlysosomal disorderslysosomal disorders

Serge Melançon MD, FRCPC, FCCMGDirector, Biochemical Genetics Services

February 2010February 2010

Ernest GAUCHER (1854-1919)

Gaucher cell 1882

Type 1 Gaucher Disease:acid β – glucosidase deficiency

enlargement and dysfunction of the liver and spleen, displacement of normal bone marrow by storage cells,

and damage to bone leading to infarctions and to fractures rare adult-onset patients have presented early

symptoms of Parkinson disease.

The clinical manifestations result from glucosylceramide engorged macrophages causing:

Type 1 Gaucher Disease:acid β – glucosidase deficiency

Some patients with severe visceral (liver and spleen) enlargement have minimal skeletal involvement,

Some with severe bone disease have minimal visceral disease.

In others, visceral involvement and skeletal involvement are approximately equal in severity.

The type of mutation seems to have less influence on the sites of disease involvement, than on overall visceral disease severity.

Type 1 Gaucher Disease

• Patients may be diagnosed as late as the eighth or ninth decade of life.

• Asymptomatic "patients" are ascertained only in the course of family studies or population surveys.

• Mildly affected individuals are almost invariably found to have the 1226G/1226G (N370S/N370S) genotype.

• Median age of appearance of the first clinical symptoms of patients with this genotype is about 30 years.

• Neurological: Parkingsonism• Skeletal: avascular necrosis, lytic lesions, chronic

osteomyelitis (after splenectomy) osteoporotic vertebral crush fractures, osteonecrosis of pelvis

• Pulmonary: Fibrosis, emphysema• Neoplastic: hematopoietic malignancies• Immune: polyarthropathy, coeliac and liver diseases• Vitamin B12 deficiency• Co-morbidities: viral or alcoholic hepatitis

Emergent concepts in GD

Diagnosis of Gaucher Disease• Assay of acid β-glucosylceramidase enzyme

activity in WBC or skin fibroblasts (unreliable for carrier detection)

• Bone marrow examination The changes are nonspecific, and bone marrow examination is not a reliable diagnostic test.

• Molecular Genetic Testing sensitivity11 targeted mutation analysis 98%Gene sequence analysis 99%

FD case report • Two males of Italian descent who were identified at ages 38 and

42 years during evaluations for hypercholesterolemia and rheumatoid arthritis, respectively.

• The finding of proteinuria in each led to renal biopsies that revealed

With podocytes diffusely distended by numerous intracytoplasmic vacuoles

accumulation of lamellated crystalline structures in the cytoplasm of endothelial cells

Fabry disease• Low levels of α-galactosidase A activity

confirmed their diagnoses.• Neither had acroparesthesias, angiokeratoma,

anhidrosis, or corneal whorling.

Cornea verticillataAngiokeratomas

α - Galactosidase A Deficiency: Fabry Disease

• X-linked recessive • Systemic deposition of glycosphingolipids

with terminal α-galactosyl moieties (GL3) in body fluids and in the lysosomes of endothelial, perithelial, and smooth-muscle cells of blood vessels.

• Deposition also occurs in ganglion cells, and in many cell types in the heart, kidneys, eyes, and most other tissues.

• Progression is organ-specific in severity and pace, and does not clearly follow a typical pattern or sequence in individual patients or cohorts of patients

• Multi-organ assessment and monitoring are required to determine disease severity

• Early involvement leads to early symptoms involving the peripheral and autonomic nervous system

• Late complications involve the heart, kidneys, and cerebrovascular system

α - Galactosidase A Deficiency: Fabry Disease

• Among adults, the age at diagnosis and age at initiation of ERT were reported to occur 10 and 8 years later in females than males, respectively.

• Women develop renal, cardiac, and cerebrovascular manifestations of Fabry disease and a greater effort must be made to diagnose and monitor these patients.

• Nearly half of the 138 Fabry Registry patients who reported strokes, experienced them prior to being diagnosed with Fabry disease.

• This highlights the need for earlier diagnosis, so patients can be monitored for risk factors associated with stroke.

α - Galactosidase A Deficiency: Fabry Disease

• Children were reported to be diagnosed at a median age of 9 years for both genders.

• They experienced substantial symptoms, and few were treated with ERT or received pain management.

• Children with Fabry disease should be monitored for signs/symptoms and their neuropathic pain should be treated appropriately.

α - Galactosidase A Deficiency: Fabry Disease

Diagnosis of Fabry Disease

1. Periodic crises of severe pain in the extremities (acroparesthesias)

2. Vascular cutaneous lesions (angiokeratomas)

3. Hypohidrosis

4. Characteristic corneal and lenticular opacities

5. Stroke

6. Left ventricular hypertrophy

7. Renal insufficiency of unknown etiology

Fabry disease should be considered in males and females with the following signs:

Diagnosis of Fabry Disease

• Alpha-galactosidase A (α-Gal A) enzyme activity (Unreliable for carrier detection)

• Molecular Genetic Testing sensitivity• Sequence analysis/mutation scanning ~ 100%

in males, unknown in females• Determination of urinary GL3 appears to be a

reliable screening test in affected individuals

(Auray-Blais C et al. Molecular Genetics and Metabolism 93 (2008) 331–340)

PD case report• 32 years-old female with

back pain

• Progressive proximal muscle weakness

• Exercise-induced urinary incontinence

• Disproportionate atrophy of the paraspinal muscles seen on CT scanning

PD case report• No signs of cardiomyopathy on heart US

• Somnolence, morning headache, orthopnea, and exertional dyspnea

• Obstructive sleep apnea

• Pulmonary function revealed diminished vital capacity

Pompe is a familial, pan-ethnic Disease Estimated prevalence <10,000 patients

worldwide

Higher frequency in individuals of following descent:-African American-Dutch-Chinese

Clinical Manifestations Pompe disease is a metabolic myopathy (cardiac, skeletal and

smooth muscle) with a continuum of clinical manifestations From early onset + rapid progression to death To later onset + slower progression

(longer survival with marked morbidity)

• Clinical spectrum determined by: GAA mutations: fully deleterious partially deleterious GAA activity: total deficiency partial deficiency Glycogen accumulation and muscle damage: rapid slower

A spectrum of GAA Gene Mutations Exists In Pompe Disease

R854X5%

GAA mutations Genzyme Clinicals n=340 alleles

As of November 2005, 230 cases genotyped at Genzyme; 59 novel mutations

c.-32-13T>G(22%)

c.525delT(6%)

Del Ex18(6%)

R854X(5%)

(Genzyme data; n=340 alleles)

Patients with Pompe Disease Share a Common Pathophysiology

Total deficiency

Partial deficiency

GAA Mutations GAA Deficiency Muscle Pathology

Less rapid glycogen accumulationAge at symptoms: adulthood

Rapid glycogen accumulationAge at symptoms: <1 year

OR

Pompe Disease: Progression

Rate of Clinical Deterioration

Rapid Slower

Disease Duration

[Early symptom onset] [Later symptom onset]

Longer(with significant morbidity)

Short(death in 1st year of life)

PLUS

Picture from IPA websiteFrom Nyhan and OzandAtlas of Metab Dis

Baseline, age 8 mos.

Myopathy

Cardiomyopathy

Quadriceps

Heart

Pompe Disease: Onset in Infancy

Courtesy Dr. B. Byrne

Pictures from the IPA Website

Loss of ambulation Respiratory Failure

Pompe Disease: Late Onset

1st symptoms

Progressive muscle weakness

Use of ambulatory devices (48%)

Use of ventilator support (37%)

Progressive Muscle Weakness Leads to Loss of Independent Ambulation and Respiratory Failure

(IPA Dutch Cohort; n=54)

Hagemans et al. Brain 2005

Diagnosis of Pompe Disease

Acid alpha-glucosidase (GAA) enzyme activity. In cultured fibroblasts (6 weeks) or in peripheral blood (blood spots)

Complete deficiency (activity <1% of normal controls) of GAA enzyme activity in classic infantile-onset PD.

Partial deficiency (activity that is 2%-40% of normal controls) of GAA enzyme activity non-classic infantile-onset and late-onset forms

Muscle biopsy. 20%-30% of individuals with late-onset Pompe disease with documented partial enzyme deficiency may not show any muscle-specific changes

Specific tests

Diagnosis of Pompe Disease

• Sequence analysis/mutation scanning sensitivity

p.Arg854X ~ 50%-60% p.Asp645Glu ~ 40%-80% IVS1 -13T>G ~ 50%-85%

 Other GAA sequence variants 83%-93%  

Molecular Genetic Testing

Overall Survival at 18 Months of Age

Clinical Trial Patients

Untreated Historical Cohort

18/18 trial patients[100%]

1/61 untreated controls[2%; 95% CI: 0% - 6%]

95% Confidence Intervals

Survival Free of Invasive Ventilation at 18 Months of Age (Primary End Point)

15/18 trial patients [83%; 95% CI: 66% - 100%]

1/61 untreated controls[2%; 95% CI: 0% - 6%]

Clinical Trial Patients

Untreated Historical Cohort

95% Confidence Intervals

Changes in LV Mass (by cardiac echo)

Upper Limit of NormalUpper Limit of Normal

All patients with data showed reduction in LV mass: 58% after 1 year of Myozyme, in averageM

eqn

LVM

Z-s

core

Baseline Week 26 Week 52

-1

0

1

2

3

4

5

6

7

8

9+7.1 Z-score

+3.2 Z-score

Challenges: Treat Early

0

10

20

30

40

50

60

% 70

47%

28%

Percent of Muscle Glycogen Increases with Age

< 6 months 6 months – 3 years

Functional Status Worsens with Longer Disease Duration

Late onset PD Trials

Forced Vital Capacity (FVC)

Study 2704, ‘LOTS’: Design

• 90 patients enrolled at 8 sites in US and EU– 10 to 70 years (Mean = 44.5 years)– 0 to 45.4 years symptoms duration (Mean = 15.7 years)

• Randomized, double-blind, placebo-controlled 12 month study with 2:1 drug to placebo assignment

– US – 58 patients (2 pediatric, 56 adults)– EU – 32 patients (2 pediatric, 30 adults)

• All patients were ambulatory and not invasively ventilated• Pulmonary and muscle strength and function were

assessed every 12 weeks – Primary Endpoints

• Distance walked in 6 minutes• Forced Vital Capacity (FVC)

• Results– Clinical benefits were seen for respiratory and motor function

Jessica, MPS I

MPS I

• Progressive, inherited• Lysosomal storage disorder

– deficiency of -L- iduronidase enzyme– progressive accumulation of

glycosaminoglycans (GAGs)

Multisystemic Manifestations

• Brain• Ears, nose, throat• Lungs• Heart• Liver• Spleen• Bones and joints

MPS I Major Manifestations

Facial dysmorphism

Communicating hydrocephalus

Developmental delay

Hearing loss

Corneal clouding

Skeletal abnormalities

Obstructive airway disease

Cardiac complications

Hepatomegaly

Joint stiffness

MPS I Spectrum of DiseaseMPS I Spectrum of Disease SeveritySeverity

HurlerHurler

LL-iduronidase deficiency-iduronidase deficiency

Less severeLess severeSevere Severe

Hurler-ScheieHurler-Scheie ScheieScheie

Disease Progression: Severe MPS IDisease Progression: Severe MPS I

10 months 12 months

22 months 34 months

39 months

Disease Progression: Moderate MPS I

6 years

Disease Progression: mild MPS I

3 years 4 years

6 years 8 years

11 years

Diagnosis of MPS I• Patients see several specialists before diagnosis • Presumptive diagnosis

– observation of symptoms and laboratory findings• coarse facial features• hepatosplenomegaly• skeletal, joint, or ocular findings characteristic of MPS I

• Family history/medical pedigree• Analysis of urinary GAGs

Enzyme Assay: Definitive Diagnosis

• Assay for a-L-iduronidase activity– measure in leukocytes, cultured skin fibroblasts,

serum, plasma

• Markedly deficient in affected patients– less than 1% normal

• Enzyme activity does not correlate with disease severity

THE END THE END OF OF

LYSOSOMALLYSOSOMALDISORDERSDISORDERS