Transcript MATERNAL PKU AND OTHER METABOLIC DISORDERS

MATERNAL PKU: LONGER TERM
OFFSPRING OUTCOME RELATED
TO PRENATAL AND POSTNATAL
FACTORS
Harvey L. Levy, MD, Susan E. Waisbren, PhD,
Fran Rohr, MS, RD, Vera Anastasoaie, Stephanie Petrides
Boston Children’s Hospital
Harvard Medical School
Dr. Levy has the following disclosures
Maternal PKU Study, NPKUA
Maternal PKU Study, Milton Fund
Enzyme Therapy for PKU, BioMarin
Pharmaceuticals
GMP therapy for PKU, FDA
Urea Cycle Disorders, NIH
Dr. Charles E. Dent: Richards made a chance
observation from a phenylketonuric mother at
the mental defective colony in Caterham, near
London. She had three children …………….. All
three children were mentally retarded from
birth but had no abnormal amino acids in their
urine. We felt that it might well have been the
toxicity of the mother’s high blood
phenylalanine level that damaged their brains
in utero.
From Discussion at the 23rd Ross Pediatric
Research Conference 1957
PAH
Phenylalanine
Tyrosine
BH4
Phenylpyruvic Acid
Phenyllactic Acid
Phenylacetic Acid
MATERNAL PKU:
A PROBLEM
BORN OF SUCCESS
Aims of the Study
1. Longer term medical and intellectual
outcome of the offspring
2. Psychological-emotional-social
functioning of the offspring
3. Medical-nutritional-emotional status of the
mothers
4. Relative roles of metabolic control in
pregnancy and postnatal maternal
stimulation in offspring outcome
The Sample
27 mothers ranging from 23-48 (average
age is 40)
48 offspring ranging from 2 months-26
years (average age is 9 years)
0-2
10 subjects
3-6
15 subjects
7-11
8 subjects
12-18
12 subjects
>18
3 subjects
Measures Used In Study
 IQ (mothers and offspring)
 Executive functioning (mothers and offspring)
 Prevalence of Anxiety/Depression/ADHD
(mothers and offspring)
 Physical exam (mothers and offspring)
 Home Scale--measure of home environment
(offspring)
 Nutrition assessment (mothers)
 Labs—including blood Phe (mothers)
 Photos to look at dysmorphology (mothers,
offspring, and fathers if possible)
Offspring outcome was determined
by ABAS
ABAS- Adaptive Behavior Assessment System
(questionnaire completed by mother that includes
10 skills areas of offspring)
ABAS correlates with offspring IQ
n=27, r=0.73, p<0.0001
ABAS correlates with offspring DQ
n=11, r=0.77, p=0.005
Prenatal Metabolic Control
Started diet prior to pregnancy: 76%
In metabolic control prior to pregnancy: 41%
Control during pregnancy:
Excellent:
41% (11)
On diet prior, blood phe < 6 mg/dL throughout
Good
35% (9)
On diet prior, blood phe <6 mg/dL by 10 weeks
Fair
14% (4)
Blood phe < 10 mg/dL by second trimester
Poor
10% (3)
Blood phe in control in third trimester or never
Maternal Postnatal Diet
Mothers currently “on diet”: 52% (14/27)
On diet = taking medical food and restricting phe
Maternal Blood Phe
Average 1176 umol/L (19 mg/dL)
Range
(386-1934)
(6-32)
Prenatal Treatment vs.
Offspring Outcome
Maternal
Pre-conception
Post-conception
Offspring ABAS
98±16
92±22
Current Maternal Dietary Status vs.
Offspring Outcome
Dietary Status
On diet
Off diet
Offspring ABAS
103±16
97±12
Mother’s Prenatal and Postnatal
Diet vs. Offspring ABAS
Excellent Control
n=10
On
Diet
n=14
112±18
97±15
<85=0
<85=3
n=8
Off
Diet
Not Excellent Control
n=13
102±7
89±20
<85=0
<85=4
Conclusions
• Longer term follow-up of offspring from treated
maternal PKU pregnancies confirms that
outcome is usually within normal limits
• Offspring outcome is not only IQ but also
function (social, behavioral…) as measured by
ABAS
• Optimal offspring outcome requires not only
prenatal metabolic control but also postnatal
stimulation
• Good postnatal stimulation requires maternal
continuation of diet
Effects of Glycomacropeptide, Amino
Acid & Casein Diets on Osteopenia in
PKU Mice
Denise M. Ney, PhD, RD
Professor of Nutritional Sciences
Waisman Center
University of Wisconsin-Madison
Disclosure

D Ney is a co-inventor on US Patent
Application US-2010-0317597, GMP Medical
Foods for Nutritional Management of PKU,
which is held by the Wisconsin Alumni
Research Foundation and licensed to
Cambrooke Foods, LLC. A percentage of all
royalty payments is awarded to the inventors.

D Ney has received consulting income from
Cambrooke Foods and BioMarin.
UW-Madison PKU Bone Research Team
Denise Ney
Robert Blank
Sangita Murali
Patrick Solverson
Funding: National PKU Alliance & USDA Hatch Grant
Background

PKU is associated with low bone mass, or
osteopenia, and fractures in early adulthood.
– 57% of 28 patients had osteopenia/osteoporosis
• Perez-Dueñas et al. Acta Paediatr 91:800, 2002

Reduced bone mineral density (BMD) in PKU
is present from an early age onward and it
cannot be predicted by plasma phe levels.
– 20% of 53 patients studied had osteoporosis
• de Groot et al. Mol Genet Metab 101:566, 2012
What causes skeletal fragility in PKU?
The fundamental question is whether
reduced BMD is inherent to PKU or
secondary to its dietary management.
 In order to isolate the contributions of the
PKU genotype itself and dietary treatment of
PKU we have conducted a factorial
experiment in PKU mice.

Objective & Design

To determine how the PKU genotype and the
source of dietary protein affect growth, body
composition and bone development.
♂
♀
High Phe
WT
PKU
Low Phe
Casein
AA
GMP
PKU & WT Mice
Housed With Same
Sex Littermates
↓phe GMP
↓phe AA
↑phe Casein
GMP is a natural whey protein
produced when making cheese.
Pure GMP contains no phe.
Growth
Males
35
Females
25
Body Weight (g)
Body Weight (g)
30
25
20
15
Genotype x Diet p = 0.0053
10
WT CAS (15)a
PKU CAS (16)b
WT AA (13)b
PKU AA (12)b
WT GMP (17)b
PKU GMP (11)b
20
15
Genotype x Diet p = 0.0257
10
WT CAS (19)a
WT AA (14)ab
WT GMP (20)b
5
PKU CAS (14)c
PKU AA (18)bc
PKU GMP (11)bc
5
3
6
9
12
15
Age (Week)
18
21
24
3
6
9
12
15
18
21
Age (Week)
Solverson, P et al Am J Physiol Endocrinol Metab 302:E885-95, 2012
24
Metabolic Phenotyping Platform
●Food & water intake
●O2 consumption &
CO2 production
PKU mice show increased energy
expenditure with casein diet
a
120
ab
110
PKU
b
VO2 (ml/hr)
100
c
c
c
3-15%
WT
90
80
WTCAS (16)
PKUCAS (21)
WTAA (23)
PKUAA (18)
WTGMP (26)
PKUGMP (16)
70
60
12
14
16
18
20
Lean Body Mass (g)
22
24
26
GMP Diet Normalizes Food
Intake in PKU Mice
genotype x diet p = 0.0193
5
sex p = 0.0404
males - a
females - b
a
a
4
b
b
b
3
GMP (17)
AA (18)
Casein (21)
GMP (30)
1
AA (23)
2
Casein (17)
Food Intake (g/day)
b
0
Wild Type
PKU
Values with different letter superscripts are significantly different, p<0.05
AA Diet Increases Kidney Workload
in both WT and PKU Mice
Kidney Mass
24 Hour Water Intake
8
2.0
0.0
Wild Type
PKU
2
b
b
b
GMP (16)
GMP (22)
AA (30)
Casein (30)
GMP (36)
0.4
AA (27)
0.8
4
a
a
AA (18)
1.2
6
Casein (21)
c
GMP (30)
c
AA (23)
c
ab
Casein (20)
b
Casein (34)
g/100gBW
1.6
24 hr Water Intake (ml)
a
a
0
WT
PKU
Values with different letter superscripts are significantly different, p<0.05
Does PKU increase energy needs?

Resting energy expenditure is ~5-10% higher
in adolescent females with PKU than that
predicted by standard equations.
– J Am Diet Assoc 110:922-25, 20101
– Am J Clin Nutr 62:797-804, 1995

Reduced growth occurs in children with PKU
– Mol Genet Metab 101:99-109, 2010
– J Pediatr 26:1-11, 2002
Dual Energy X-Ray Absorptiometry (DXA)
PKU mice show reduced whole-body bone
mineralization compared to WT mice
BMD (mg/cm2)
60
a
b
WT (98)
PKU (86)
50
40
30
20
10
0
Femur Strength: 3 Point Loading Test
Load (F)
Displacement
Loading force being
applied to a mouse femur
Load-Displacement Curve
Max Load
16
14
Load, N
12
10
Yield
Point
Post-Yield Displacement
8
Fracture
6
4
2
-0.1
0.1
-2
0.2
0.3
0.4
0.5
Elastic
Deformation
Displacement, mm
0.6
0.7
0.8
PKU mice show bones that are brittle and
break easily
Yield Load
20
18
Wild Type
PKU
Fracture
14
12
0.5
a
b
0.4
0.3
0.2
0.1
0.0
10
WT (116)
8
PKU (101)
6
4
2
Post-Yield Displacement
0
0.0
0.2
0.4
0.6
Displacement (mm)
0.8
Yield Load (N)
Load (N)
16
PYD (mm)
0.6
16
a
14
b
12
10
8
6
4
2
0
WT (116)
PKU (101)
PKU mice show reduced femoral bone
mineralization compared to WT mice
Bone Mineral Content
Bone Mineral Density
2
a
30
b
50
40
30
20
25
20
15
10
10
5
0
0
WT (116)
PKU (101)
a
b
BMC (mg)
BMD (mg/cm )
60
WT (116)
PKU (101)
How the casein, AA and GMP
diets affect bone size and
strength?
GMP Increases Bone Size in PKU & WT Mice
Cross Sectional Area
Casein
1.4
(mm2)
1.2
AA
a
1.0
b
a
AA
GMP
0.8
0.6
0.4
0.2
0.0
Casein
GMP
WT Mice
Fed Casein
GMP Improves Bone Strength in PKU
and WT Mice Compared with AA Diet
18
ab
b
a
AA
GMP
Max Load (N)
16
14
12
10
8
6
4
2
0
Casein
WT Mice
Fed Casein
Summary

PKU mice have femora that are
brittle and weak. This suggests
defects in both collagen synthesis
and mineralization.

GMP increases bone size and strength; femora
tolerate a higher max load before fracture
compared with the AA diet.
– How does GMP work to improve bone strength in mice?
What causes skeletal fragility in PKU?
Inherent to PKU genotype and/or
 Secondary to management with an AA diet.


Conclusion
 Skeletal
fragility is inherent to the PKU
genotype and is attenuated by a GMP
compared with an AA diet in mice.
 Future research is needed to determine
if improved low-phe diets containing
GMP reduce skeletal fragility in human
PKU.
Take Home Message: How can bone
health be improved in PKU?
 Follow
a low-phe diet to improve
growth and bone development
 Include
weight bearing exercise
each day