Expanded Newborn

Screening:

Clinical Impact

(Tandem ms/ms)

DR.AMIR ABDELAZIM

CLINICAL PATHOLOGY SPECIALIST

Newborn Screening

A state mandated public

health program that begins

with a “heel poke” for every

baby before hospital discharge

First screen must be taken 48-52

hours of life regardless of

feeding status or weight

Blood Sample on Guthrie Filter Paper Card

Who is screened?

Every newborn must be tested prior to discharge

from the hospital or within five days of age

Second screen strongly recommended between

7 and 14 days of age for sick and premature

baby

Third screen recommended for sick and

premature infants

Why do newborn screening?

Screen a presumably healthy

newborn population

Detect disease before

symptoms present clinically

Goal: Prevent or reduce

morbidity and mortality

Criteria for Newborn

Screening

Important condition

Acceptable treatment available

Facilities for diagnosis and treatment

Difficult to recognize early

Suitable screening test

Natural history known

Cost-effective to diagnose and treat

Wilson & Jungner, 1968

Tandem Mass Spectrometry

(MS/MS) High Impact and High

Throughput

Many diseases, one test is cost-effective

MS/MS allows for rapid, simultaneous analysis

and detection of many disorders of amino

acid, organic acid, and fatty acid metabolism

Tandem Mass

Spectrometer (MS/MS)

MS/MS Methodology

Blood spots punched (3/16th inch disc)

Stable isotope internal standards added

Butyl esters derivatives made (in derivatisedmethod)

Automatic injection into MS/MS via 96 well plates

Sample set up determines which masses and therefore which compounds are detected

2 minute analysis time

Automated data processing for results

MS/MS Methodology –

continued

Compounds analyzed are amino acids and acylcarnitines

Amino acids – to identify PKU, MSUD, homocystinuria , cittrulinemia ,ASA , Tyrosinemia

Acylcarnitine –for identification of organic acidurias and fatty acid oxidation disorders

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* ** *

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C2

100%

Inte

ns

ity

* internal standards

Control

Inte

ns

ity

100%

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MCAD

C2

C16

C8

C10:1C6

MS/MS Plasma Acylcarnitines

MS/MS Plasma Amino Acids

What is the scope of newborn

screening?

Screen ~60,000 newborns

Track ~ infants with abnormal results

Prevent ~ babies from death or disability

Which disorders should be

identified?

Kuwait National NBS screen for 22 disorders

Screen tests done for all newborn inside Kuwait

New disorders plan to test in the future

Amino Acid Disorders

AA that are not used to make proteins are recycled by their specific metabolic pathways.

Enzymatic deficiencies in these pathways lead to various clinical phenotypes.

Diagnosed by plasma amino acids, urine amino acids, and/or urine organic acids (takes 2-5 days)

PKU: severe, permanent ID

MSUD: ID, hallucinations, ataxia

HCY: connective tissue damage (joints, heart), ID, psychiatric disturbances

CIT: risk of hyperammonemia ID, coma, death

ASA: brittle hair, liver disease ID

TYR I: acute or chronic liver disease, liver cancer, neurologic pain crises

Organic Acid Disorders

Organic acids are breakdown products of protein and fatty acid metabolism. Defects in their breakdown lead to (generally): Vomiting, metabolic

acidosis, elevated ammonia in crises

ID, motor delay, ataxia, cardiac/renal/pancreatic problems

Diagnosed by urine organic acids and/or plasma acylcarnitines

IVA: Isovaleric acidemia

GA I: Glutaric acidemia type I

HMG: 3-OH 3-CH3 glutaric aciduria

MCD: Multiple carboxylase deficiency

MUT: Methylmalonic acidemia (mutase deficiency)

3MCC: 3-Methylcrotonyl-CoA carboxylase deficiency

Cbl A,B: Methylmalonic acidemia

PROP: Propionic acidemia

BKT: Beta-ketothiolase deficiency

Fatty Acid Disorders

Fatty acid disorders lead to impaired energy production

Hypoglycemia, cardiomyopathy, muscle weakness can be seen

Diagnosed by plasma acylcarnitines, and urine organic acids can be helpful

MCAD: Medium-chain acyl-CoA dehydrogenase deficiency

VLCAD: Very long-chain acyl-CoA dehydrogenase deficiency

LCHAD: Long-chain L-3-OH acyl-CoA dehydrogenase deficiency

TFP: Trifunctional protein deficiency

Who is identified?

1. Patients who need active management

Symptomatic at diagnosis

Strong evidence of pathology if untreated

Examples: PKU, classic galactosemia, MSUD,

PROP, etc.

Who is identified?

2. Patients with disorders known to pose risk but

reduced penetrance

i.e., probably not everyone needs to be treated

HPHE, MCAD

Both are/have mild ends of the spectrum that

have only been identified through NBS

MCAD mutation c.199 C>T

Never seen in patients picked up clinically

Who is identified?

3. Patients who may not need any management

Disorders considered extremely rare but seen in

large numbers via NBS programs

Reported cases have significant morbidity

NBS pickups are mostly mild

3MCC, SCAD

Biochemical phenotype

What are we screening

for?

8 OA 4 FAO 6 AA4 Others

IVA

GA I

HMG

MCD

MUT

3MCC

Cbl A,B

PROP

BKT

MCAD

VLCAD

LCHAD

TFP

PKU

MSUD

HCY

CIT

ASA

TYR I

CH

BIOT

CAH

GALT

Components of Newborn

Screening

Sampling

hospital NSO

Screening

Tandem & DELFIA Labs

Reporting

to NSOs

Referral

to endocrine&metabolic sp.

for follow up and monitoring

Effective NBS requires a

close working relationship

between hospitals NSOs,

newborn screening labs,

co-ordinators ,endocrine

specialist and metabolic

specialist .