Muscular Dystrophies

Slide 1 · Muscular Dystrophies

Mechanisms • tissue injury • clinicopathologic patterns

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Learning objectives

Explain the structural and molecular basis of progressive muscle injury.

Relate dystrophin deficiency to histomorphology and Duchenne/Becker phenotypes.

Distinguish limb-girdle, Emery–Dreifuss and facioscapulohumeral dystrophies.

Integrate clinical patterns, CK, genetics and selected muscle biopsy findings.

Mechanism

Morphology

Clinical phenotype

Diagnosis

Slide 3 · Progressive damage defines muscular dystrophy

Inherited disorders characterized by chronic, progressive skeletal muscle injury.

Most noncongenital forms become clinically evident from childhood to adulthood.

Loss of functional myofibers eventually exceeds regenerative capacity.

Inherited protein defect

Repeated myofiber damage

Insufficient repair

Progressive weakness

Slide 4 · Age at presentation defines important boundaries

Group

Typical presentation

Key distinction

Congenital myopathy

Infancy

Structural muscle abnormalities; course may be static

Congenital dystrophy

Infancy

Progressive dystrophic damage ± CNS abnormalities

Other dystrophies

Childhood–adulthood

Progressive skeletal muscle injury

Slide 5 · Different molecular defects converge on myopathy

The molecular lesion predicts the affected cell compartment.

The clinical pattern can guide the differential before molecular confirmation.

Cardiac or neurologic involvement is not uniform across categories.

Sarcolemma

Sarcomere

Nuclear envelope

Gene regulation

Extracellular matrix

Slide 6 · Repeated injury creates a cumulative tissue deficit

Necrotic fibers can initially be replaced by regenerating myofibers.

Persistent injury progressively impairs normal tissue organization.

Fibrous tissue and adipocytes increasingly occupy lost muscle volume.

Necrosis

Regeneration

Repeated damage

Fibrofatty replacement

Slide 7 · Extramuscular disease changes prognosis

Several inherited muscular disorders also involve cardiac muscle.

Dystrophin is expressed in the CNS as well as skeletal and cardiac muscle.

Respiratory insufficiency and cardiac disease may become life limiting.

Skeletal muscle

Heart

Respiratory function

CNS

Slide 8 · Dystrophinopathies are X-linked conditions

Duchenne and Becker muscular dystrophies result from pathogenic DMD variants.

The DMD gene is on the X chromosome.

Dystrophinopathies include phenotypes milder than classic limb-girdle weakness.

DMD variant

Dystrophin deficiency / dysfunction

Variable skeletal ± cardiac phenotype

Slide 9 · Duchenne and Becker differ chiefly in severity

Duchenne muscular dystrophy is the severe, earlier-onset phenotype.

Becker muscular dystrophy generally begins later and progresses more slowly.

The presence of partially functional dystrophin helps explain the contrast.

Duchenne

Usually absent dystrophin

Earlier onset

Severe progression

Becker

Partially functional dystrophin

Later onset

Slower progression

Slide 10 · DMD is an exceptionally large human gene

The DMD gene spans approximately 2.3 million base pairs.

It contains 79 exons.

Dystrophin is a key intracellular constituent of the dystrophin glycoprotein complex.

X chromosome

DMD gene: 2.3 Mb

79 exons

Dystrophin protein

Slide 11 · Dystrophin bridges cytoskeleton and matrix

Dystrophin lies beneath the sarcolemma.

It links intracellular cytoskeletal proteins to transmembrane complex components.

The complex connects to extracellular laminin-containing basement membrane.

Extracellular matrix / laminin

Sarcolemma

Dystroglycan / sarcoglycan complex

Dystrophin

Intracellular actin cytoskeleton

Schematic — membrane linkage

Slide 12 · The glycoprotein complex spans the sarcolemma

Dystroglycans and sarcoglycans form a transmembrane interface.

Their extracellular connections help couple a myofiber to the matrix.

Disturbances at different points can give rise to different dystrophy groups.

Actin cytoskeleton

Dystrophin

Dystroglycan / sarcoglycan complex

Laminin-rich matrix

Slide 13 · The dystrophin complex stabilizes a contracting fiber

Muscle contraction exposes the sarcolemma to repeated mechanical stress.

Dystrophin-associated connections are thought to stabilize the membrane.

Loss of this mechanical support increases susceptibility to injury.

Intact linkage

Cytoskeleton coupled to matrix

Membrane support during contraction

Disrupted linkage

Less stable sarcolemma

Greater susceptibility to damage

Slide 14 · Membrane injury permits calcium influx

Defective membrane stabilization may create microscopic sarcolemmal tears.

Calcium entering damaged fibers triggers downstream injurious events.

Myofiber necrosis produces the characteristic destructive process.

Membrane instability

Small membrane tears

Ca²⁺ influx

Myofiber necrosis

Slide 15 · Dystrophin also participates in signaling

The dystrophin complex is not exclusively a mechanical scaffold.

Dystrophin associates with syntrophins and dystrobrevin.

Its signaling interactions include neuronal-type nitric oxide synthase (nNOS).

Dystrophin

Syntrophins

Dystrobrevin

NNOS / NO

Slide 16 · Genotype helps explain the phenotypic spectrum

Duchenne commonly results from alterations producing essentially no dystrophin.

Becker variants may permit a shortened protein with residual function.

Genotype–phenotype relationships explain many—but not all—differences.

DMD variant

Protein abundance / function

Membrane support

Clinical severity

Slide 17 · Duchenne mutations usually abolish protein expression

Deletions and frameshifting variants commonly produce a severe null phenotype.

Loss of dystrophin destabilizes the sarcolemmal linkage.

Ongoing muscle damage begins well before advanced fibrofatty change.

Loss-of-function DMD mutation

Absent dystrophin

Membrane vulnerability

Early progressive myopathy

Slide 18 · Becker variants preserve some protein function

Certain deletions or altered splicing permit synthesis of shorter dystrophin.

The residual protein retains at least partial function.

Residual function is associated with later onset and slower disease progression.

DMD variant compatible with protein

Truncated dystrophin

Partial mechanical function

Milder course

Slide 19 · Dystrophin deficiency has a broader phenotype

Some individuals develop predominant cardiomyopathy.

Others are identified through asymptomatic CK elevation.

Exercise intolerance, cramps and myalgias can also occur.

Limb weakness

Cardiomyopathy

HyperCKemia

Exercise symptoms

Slide 20 · Female DMD carriers may be symptomatic

Female carriers are not invariably free of manifestations.

Skewed X-chromosome inactivation can increase the effect of a pathogenic allele.

A symptomatic carrier may show relatively mild muscular manifestations.

Heterozygous DMD variant

Unfavorable X-inactivation

Reduced effective dystrophin

Possible symptoms

Slide 21 · Dystrophic pathology reflects chronic destruction and repair

Segmental myofiber necrosis coexists with attempts at regeneration.

Atrophic and hypertrophied fibers can occur in the same specimen.

Progressive injury eventually leads to connective tissue and fatty replacement.

Necrosis

Regeneration

Fiber-size variation

Fibrofatty remodeling

Slide 22 · Segmental necrosis is an active injury pattern

Only portions of individual muscle fibers may undergo necrosis.

Necrotic fiber segments are removed by phagocytic cells.

This process indicates active myofiber injury rather than denervation alone.

Necrotic fiber segment

Simplified tissue schematic — not a histologic specimen

Slide 23 · Regeneration accompanies ongoing necrosis

Regenerating fibers appear among injured and atrophic myofibers.

Basophilic regenerating fibers in an early Duchenne biopsy.

Regeneration does not necessarily keep pace with repeated injury.

Simplified tissue schematic — not a histologic specimen

Slide 24 · Fiber-size variation marks the dystrophic process

Small atrophic fibers coexist with enlarged surviving fibers.

Differences in caliber become increasingly striking as disease progresses.

Size heterogeneity is important but not by itself disease specific.

Simplified tissue schematic — not a histologic specimen

Slide 25 · Early fascicular architecture can be preserved

An early Duchenne biopsy can retain recognizable fascicles.

Fiber necrosis and regeneration may still be evident within the fascicle.

A deceptively preserved overall pattern does not exclude active dystrophy.

Early stage

Recognizable fascicles

Focal degeneration and regeneration

Later stage

Architectural disruption

Prominent fibrosis and fat

Slide 26 · Myophagocytosis is not diffuse inflammatory myositis

Macrophage removal of necrotic fiber material is expected after injury.

Little inflammation beyond myophagocytosis in typical early Duchenne biopsies.

Inflammatory cells must be interpreted alongside the overall pattern.

Necrotic fiber

Macrophage cleanup

Myophagocytosis

Repair / remodeling

Slide 27 · Fibrosis and fatty replacement are progressive

Collagen and adipose tissue replace lost functional muscle.

Endomysial expansion increasingly separates surviving myofibers.

Replacement drives irreversible architectural distortion.

Simplified tissue schematic — not a histologic specimen

Slide 28 · Advanced disease disorganizes fascicular architecture

Myofibers are unevenly distributed among collagen and adipocytes.

Normal muscle organization becomes markedly abnormal.

Remaining fibers range from small and atrophic to enlarged and hypertrophic.

Simplified tissue schematic — not a histologic specimen

Slide 29 · Muscle biopsy findings depend on disease stage

Early biopsy: Necrosis and regeneration with fairly preserved organization.

Intermediate biopsy: Increasing fiber-size variation and connective tissue.

Late biopsy: Extensive fibrofatty replacement may dominate the field.

Early: Active injury

Intermediate: Remodeling

Late: Replacement

Slide 30 · Dystrophin immunostaining assesses membrane expression

Dystrophin is normally demonstrable at the myofiber membrane.

Complete loss is characteristic of many Duchenne biopsies.

Reduced or altered expression can support a Becker phenotype.

Normal

Duchenne

Becker

Idealized schematic membrane staining patterns

Slide 31 · Immunostaining must be interpreted with genetics

Protein expression varies with underlying pathogenic variants.

Abnormal dystrophin labeling supports the molecular diagnosis.

Genetic testing remains the definitive confirmatory investigation.

Clinical suspicion

CK and related tests

DMD molecular analysis

Selected biopsy / IHC if needed

Slide 32 · Duchenne disease begins after a normal neonatal appearance

Affected boys usually appear normal at birth.

Earliest motor milestones may be attained despite underlying disease.

Delayed walking and later weakness may be the first recognizable indications.

Apparently normal at birth

Possible walking delay

Clumsiness / slow pace

Progressive weakness

Slide 33 · Early functional symptoms reflect proximal weakness

Clumsiness and difficulty keeping up with peers are common early complaints.

Weakness initially involves pelvic-girdle muscles.

Shoulder-girdle muscle weakness appears as the disease progresses.

Pelvic-girdle weakness

Difficulty with mobility

Additional shoulder involvement

Slide 34 · Pelvic-girdle muscles are affected before the shoulder

The distribution is initially proximal rather than purely distal.

Anatomic pattern is an important clinical clue.

Pattern recognition alone does not establish a molecular genotype.

Pelvic girdle: Early weakness

Shoulder girdle: Later involvement

Generalized functional decline

Slide 35 · Calf pseudohypertrophy masks tissue loss

Enlarged lower-leg muscles may coexist with marked weakness.

Progressive replacement by fat and connective tissue increases bulk.

Apparent muscle size is therefore not a measure of contractile strength.

Apparent enlargement

Increased calf volume

May seem well developed

Functional pathology

Lost contractile myofibers

Fibrofatty replacement

Slide 36 · Contractures and scoliosis reflect advancing disease

Progressive weakness contributes to reduced joint mobility and deformity.

Joint contractures can develop with increasing muscle involvement.

Spinal deformity and scoliosis compound functional disability.

Weakness

Contractures

Postural / spinal deformity

Further mobility limits

Slide 37 · Respiratory complications become consequential

Respiratory muscle involvement progressively reduces reserve.

Sleep-related hypoventilation can occur in advanced disease.

Respiratory insufficiency and pulmonary infections contribute to mortality.

Respiratory muscle weakness

Reduced reserve

Sleep hypoventilation

Respiratory complications

Slide 38 · Cardiomyopathy is a major dystrophinopathy manifestation

Dystrophin is normally expressed in cardiac muscle.

Deficiency can produce cardiomyopathy and arrhythmias.

Cardiac involvement may dominate survival even in milder skeletal phenotypes.

Cardiac dystrophin deficiency

Myocardial dysfunction

Cardiomyopathy / arrhythmia

Potential heart failure

Slide 39 · Dystrophin expression in the CNS has clinical correlates

Dystrophin is expressed beyond muscle, including the brain.

Learning disability and cognitive impairment may accompany Duchenne disease.

These findings vary and should not be presumed in every patient.

Dystrophin

Skeletal muscle

Cardiac muscle

CNS

Slide 40 · Duchenne prognosis involves multiple organ systems

Progressive weakness eventually limits ambulation and independence.

Pulmonary infection, respiratory insufficiency and heart failure are important threats.

Major mortality in young adulthood despite support; Individual outcomes vary.

Mobility loss

Respiratory failure

Infection

Heart failure

Slide 41 · Serum CK reflects active muscle membrane injury

Creatine kinase becomes markedly elevated during active early injury.

Leakage of muscle enzymes accompanies necrosis.

A high CK supports a muscle injury process but is not dystrophinopathy-specific.

Myofiber damage

Enzyme leakage

Marked CK elevation

Molecular work-up

Slide 42 · CK can decline as muscle mass is lost

CK often peaks during the first decade, when active destruction is prominent.

Levels can fall later despite clinically worsening disease.

Serial CK must be interpreted with stage and remaining muscle mass.

Earlier disease

More intact muscle undergoing injury

Marked CK elevation

Advanced disease

Less remaining muscle mass

CK may decrease

Slide 43 · Clinical pattern and testing are complementary

History and examination establish the pattern of weakness and progression.

Serum CK indicates active muscle damage.

Molecular testing confirms a pathogenic dystrophin alteration.

Clinical phenotype

Serum CK

Genetic testing

Integrated diagnosis

Slide 44 · Biopsy is most valuable when genetics is unresolved

Genetic testing as the ultimate confirmation.

Muscle biopsy can be informative for difficult-to-identify alterations.

Morphology and dystrophin staining provide additional protein-level evidence.

Unclear molecular result

Muscle biopsy

Dystrophic morphology / IHC

Correlate with genotype

Slide 45 · Becker dystrophy typically progresses more slowly

Symptoms may appear in later childhood, adolescence or adulthood.

Some affected individuals maintain function for much longer than in classic Duchenne.

Residual dystrophin function is a major molecular explanation.

Later recognition

Proximal weakness

Slower progression

Often longer survival

Slide 46 · Cardiac disease may dominate Becker outcome

Less severe skeletal muscle weakness does not eliminate cardiac risk.

Heart failure remains a common life-limiting complication in Becker disease.

Clinical comparisons must consider cardiac as well as skeletal phenotype.

Becker dystrophy

Milder skeletal disease

Cardiomyopathy

Heart failure

Slide 47 · Duchenne versus Becker: Integrated comparison

Dimension

Duchenne

Becker

Dystrophin

Usually absent

Usually shortened / partly functional

Onset

Typically early childhood

Later childhood to adult life

Clinical course

Severe; rapid progression

Typically milder; slower progression

Cardiac disease

Common and serious

Can be major life-limiting feature

Molecular diagnosis

DMD pathogenic variant

DMD pathogenic variant

Slide 48 · Limb-girdle muscular dystrophy is heterogeneous

A broad collection of autosomal dominant and recessive disorders.

Age of onset and clinical severity differ widely.

The shared clinical pattern is preferential proximal muscle weakness.

LGMD

Autosomal inheritance

Variable onset

Proximal weakness

Slide 49 · Limb-girdle weakness is a phenotype, not a genotype

Many molecular lesions can produce similar proximal weakness.

Clinical distribution alone cannot identify the causative gene.

Protein compartment and molecular analysis organize the differential.

Proximal weakness

Multiple gene families

Molecular diagnosis

Specific subtype

Slide 50 · LGMD genes affect several cellular compartments

Sarcoglycans: Dystrophin-associated membrane complex.

Glycosylation enzymes: α-dystroglycan processing.

Z-disk, trafficking and signaling proteins: Other mechanisms.

Sarcoglycans

α-dystroglycan glycosylation

Z-disks

Trafficking / signaling

Other proteins

Slide 51 · Sarcoglycan defects disturb structural linkage

Sarcoglycans participate in the sarcolemmal protein complex.

Pathogenic variants provide a structural route to proximal dystrophy.

The affected protein is not necessarily dystrophin itself.

Sarcoglycan mutation

Altered membrane complex

Myofiber vulnerability

LGMD phenotype

Slide 52 · Dystroglycan glycosylation modifies matrix binding

α-Dystroglycan requires post-translational glycosylation.

Genes affecting this processing can cause limb-girdle dystrophy.

Some related defects cause congenital muscular dystrophy with broader involvement.

Glycosylation gene defect

Abnormal α-dystroglycan processing

Weakened matrix interaction

Muscle disease

Slide 53 · Other LGMD pathways broaden the differential

Associated genes encode Z-disk proteins and vesicle-traffic machinery.

Additional examples include calpain-3 and lamin A/C.

A single unifying pathogenesis is not established across all LGMDs.

Sarcomere-associated proteins

Trafficking / cell signaling

Calpain-3

Lamin A/C

Slide 54 · Emery–Dreifuss dystrophy has a clinical triad

Slowly progressive humeroperoneal weakness.

Early contractures of the Achilles tendon, spine and elbows.

Cardiomyopathy associated with conduction abnormalities.

Humeroperoneal weakness

Early contractures

Conduction disease

Slide 55 · EDMD targets the nuclear-envelope apparatus

The X-linked form is associated with emerin variants.

An autosomal form is associated with lamin A/C variants.

Both proteins are associated with the inner nuclear membrane.

Emerin

Lamin A/C

Nuclear-envelope schematic

Slide 56 · Cardiac conduction defects are diagnostic clues

The combination of contractures and conduction disease is particularly suggestive.

Cardiomyopathy can coexist with muscular weakness.

Muscular severity alone does not describe the cardiologic phenotype.

Early contractures

Humeroperoneal weakness

Conduction abnormality

Consider EDMD

Slide 57 · How nuclear-envelope defects cause EDMD remains unclear

Nuclear shape and mechanical stability during contraction may be affected.

Altered chromatin organization and gene expression are plausible mechanisms.

Robbins explicitly characterizes the full disease mechanism as unknown.

Proposed mechanical model

Fragile nuclear envelope

Stress during contraction

Proposed regulatory model

Changed chromatin organization

Altered expression

Slide 58 · FSHD has a characteristic distribution of weakness

Facial muscles and the shoulder girdle are prominently involved.

FSHD is described as an autosomal dominant muscular dystrophy.

The pattern differs from the more general limb-girdle phenotype.

Facial weakness

Shoulder-girdle weakness

Autosomal dominant inheritance

Slide 59 · Facioscapulohumeral dystrophy involves DUX4

DUX4 encodes a transcription factor normally silenced in most somatic tissues.

Abnormal expression in skeletal muscle is associated with toxicity.

The fundamental defect is epigenetic derepression rather than sarcolemmal protein loss.

Loss of DUX4 repression

DUX4 transcription

Toxic myofiber effects

FSHD phenotype

Slide 60 · Chromatin relaxation permits DUX4 expression

Normal somatic DUX4 silencing depends on repressive chromatin state.

Altered regulatory sequences can reduce DNA methylation and relax chromatin.

The resulting DUX4 derepression drives muscle pathology.

Repressive chromatin

Altered methylation / relaxation

DUX4 expression

Myofiber injury

Slide 61 · Different regulatory routes converge on DUX4

Most cases involve changes in regulatory sequences affecting repression.

A smaller fraction involve mutations in chromatin repressors such as SMCHD1.

The common mechanistic endpoint is inappropriate DUX4 transcription.

Regulatory-sequence changes

Chromatin repressor variants

(e.g., SMCHD1)

Reduced epigenetic repression

Abnormal DUX4 expression

Slide 62 · The clinical pattern helps rank dystrophy diagnoses

Entity

Characteristic clues

Key molecular mechanism

Duchenne

Early progressive proximal weakness; pseudohypertrophy

DMD; dystrophin usually absent

Becker

Later onset; slower skeletal course

DMD; residual dystrophin

LGMD

Preferential proximal weakness; variable course

Multiple structural / enzymatic pathways

Emery–Dreifuss

Early contractures; cardiac conduction disease

Emerin / lamin A/C

FSHD

Facial and scapular weakness

DUX4 derepression

Slide 63 · Congenital dystrophy is a related—but distinct—category

Unlike the major noncongenital dystrophies, onset is during infancy.

The parent Robbins section includes extracellular matrix and α-dystroglycan defects.

Some congenital entities also feature eye or CNS developmental abnormalities.

Congenital onset

Progressive muscle damage

Matrix / receptor defects

Variable extra-muscular disease

Slide 64 · Congenital matrix disorders include collagen VI and merosin

Ullrich congenital muscular dystrophy is linked to collagen VI genes.

Merosin deficiency is linked to LAMA2.

These defects involve extracellular matrix components surrounding muscle fibers.

Collagen VI defects

Ullrich congenital muscular dystrophy

Hypotonia; Contractures; Distal hyperextensibility

LAMA2 defects

Merosin-deficient dystrophy

Extracellular matrix linkage abnormality

Slide 65 · α-Dystroglycan defects can affect muscle, brain and eye

Glycosylation of α-dystroglycan supports its extracellular interactions.

Severe dysfunction can cause congenital muscle disease with CNS and eye defects.

Milder defects may be predominantly skeletal-muscle disease.

Abnormal α-dystroglycan glycosylation

Dysfunctional matrix receptor

Myopathy ± CNS / ocular defects

Slide 66 · Case A: Early pelvic weakness and calf enlargement

Illustrative scenario: A boy has delayed walking, poor pace with peers and enlarging calves.

Clinical examination suggests progressive proximal weakness.

Marked serum CK elevation strengthens suspicion of dystrophinopathy.

CLINICAL CLUES

Delayed walking

Pelvic-girdle weakness

Calf pseudohypertrophy

Marked CK

Which disorder should lead the genetic differential?

Slide 67 · Case A: Connect genotype to pathologic consequences

A severe Duchenne phenotype is the leading clinical consideration.

DMD molecular testing is needed for diagnostic confirmation.

The predicted mechanism is loss of dystrophin-mediated membrane stability.

DMD variant

Absent dystrophin

Myofiber damage

Progressive weakness

Slide 68 · Case B: Weakness plus early elbow contractures

Illustrative scenario: Slowly progressive weakness accompanies early elbow and Achilles contractures.

Cardiac assessment shows conduction abnormality.

The combination is characteristic of Emery–Dreifuss dystrophy.

CLINICAL CLUES

Humeroperoneal weakness

Early joint contractures

Conduction abnormality

Which nuclear-envelope proteins are implicated?

Slide 69 · Case B: Recognize nuclear-envelope pathogenesis

Emerin and lamin A/C are principal proteins in the source description.

Mechanical and transcriptional consequences are both proposed.

The detailed causal link from mutation to phenotype remains unresolved.

Nuclear envelope

Mechanical stability

Chromatin organization

Cardiac / muscle phenotype

Slide 70 · Case C: Prominent facial and scapular weakness

Illustrative scenario: Weakness mainly affects facial and shoulder-girdle muscles.

The phenotype raises consideration of FSHD.

The distinctive mechanism involves inappropriate DUX4 expression.

CLINICAL CLUES

Facial muscle weakness

Shoulder-girdle weakness

Autosomal dominant pattern

What is the molecular endpoint?

Slide 71 · Five mechanistic anchors

Disease group

Mechanistic anchor

Duchenne / Becker

Quantity and residual function of dystrophin

LGMD

Diverse structural, metabolic and signaling protein defects

Emery–Dreifuss

Emerin / lamin A/C; nuclear-envelope dysfunction

Facioscapulohumeral

Epigenetic derepression of DUX4

Congenital dystrophy

Matrix or α-dystroglycan linkage defects

Slide 72 · Diagnostic synthesis: Phenotype, tissue and gene

Distribution and age of onset guide the initial clinical differential.

Serum CK supports active muscle injury but is not gene specific.

Molecular analysis generally confirms dystrophinopathies; Biopsy adds value selectively.

Never ignore cardiac or respiratory involvement when assessing severity.

Pattern recognition

Biochemical evidence

Molecular confirmation

Multisystem assessment

Slide 73 · Primary source and evidentiary limits

Robbins, Cotran & Kumar: Pathologic Basis of Disease, 11th ed. (2026).

Chapter 27, Peripheral Nerves and Skeletal Muscles, pp. 1120–1123.

Conceptual diagrams and muscle schematics are original editable teaching illustrations.

No authentic biopsy photograph was embedded; original textbook plates were not available for direct verification.