Transcript Dealing with carriers of hemophilia

Dealing with carriers
of hemophilia
Alison Street
Alfred Health, Melbourne,
Australia Oct 2011
The most famous
hemophilia carriers in
history

Genotype of the Royal
Disease recently
identified as
IVS 3-3A>G
in the Factor IX gene

If he were born today
what would we advise
his female relatives
about their own health
and carrier status?
She needs to know
 It
has been estimated that for each male with Factor
VIII or IX deficiency that there may be from two up to
five female carriers of the responsible genetic
mutation which has impact on
 her
male offspring (50% chance of being affected)
 her
female offspring (50% chance of being a carrier
AND
and implications for herself
She may have symptoms of mild hemophilia
and risks of bleeding if she has low factor
levels
Reduced factor levels are found in up to 80%
of carriers and 20% have levels in the “mild
hemophilia” range (5-30% activity, ref range
50-150%)
Who are the carriers
and how should we identify and advise them,
particularly in relation to
 understanding hemophilia and their own risks
of bleeding
 understanding their genetic risk of being a
carrier and learning about
 peri -delivery care?
Bleeding problems in women
 The
woman may have bleeding problems
(particularly with menses) and needs clinical
assessment and measurement of the
coagulation factor that is reduced in her male
relatives
 Definitive testing is by genetic analysis
 Remember
that a normal level of factor
does NOT mean that she is not a carrier
Obligatory carrier
The daughter of a man with hemophilia
Proven carrier
A woman with both an antecedent and a
descendent relative with hemophilia. The
gene must have passed through her.
Probably carrier or
possible carrier
The mother of an isolated case of hemophilia
Potential carrier
A female whose position in a family suggests
that she might have an inherited the mutant
gene, e.g. the sister of a male with
hemophilia
Genetics of hemophilia A and B, An Introduction for Clinicians 2009. Carol K Kasper, M.D., Carolyn H. Buzin, Ph.D.
WFH Publications
Genetics of Haemophilia
Anne Goodeve
Sheffield Molecular Genetics Service
[email protected]
available on WFH website www.wfh.org
 Anne’s
presentation introduces hemophilia and its
inheritance pattern
 It describes the mutations responsible for F VIII and
IX deficiency and their analysis
 It provides an algorithm for testing and web-based
and literature resources
 Principally directed at molecular biology services
 Updated lab manuals (2010) also now available on
WFH website
GENETICS
OF HEMOPHILIA A AND B
An Introduction for Clinicians,
2009
by
Carol K. Kasper, M.D.
and
Carolyn H. Buzin, Ph.D.
What information is critical to
potential carriers?

Advice that phenotype (plasma factor level)
information (and its management where support is
required,) is essential for procedures to be safely
performed

Emphasis, that although factor levels may be
reduced in carriers (up to 80%), normal factor levels
do NOT exclude carrier status

Provision of current information about hemophilia
including DNA analysis where appropriate
AND LISTENING TO CONCERNS
Reasons for potential carriers to
seek information, including DNA
analysis

Gives knowledge of their status including phenotype
assessment and personal risks of bleeding

Allows informed reproductive options where
culturally appropriate

Permits preparation for delivery

Permits preparation for raising a child with
hemophilia
Reasons for potential hemophilia
carriers to NOT seek clinical advice
or testing

Result may not be thought necessary for
personal decision making.

Encouragement required to seek knowledge
of personal risks

Fear of altering relationships/family concerns
Consultation with other specialists may be
sought by a carrier and can be very valuable.

Carriers at risk of bleeding require
“comprehensive care”

Hematologists, who know the problems of
hemophilia, should support other consultants to
understand the inheritance and clinical
consequences of haemophilia as well as
addressing the carrier’s own health issues.
Care and treatment of Carriers

With improved care and longevity of men with
haemophilia, more carriers are being born

We can define carriers by


Obligate/possible/phenotype status
DNA analysis
Genetic testing, where available, is performed
as part of a supportive clinical encounter with

Informed clinicians

Genetic counsellors

Excellent laboratory scientists
When should women know of their
carrier status?


Aim to have discussions about the possibility
and consequences of being a carrier before
marriage and pregnancy
so that women are tested and aware of their
bleeding risks and where appropriate their
genetic status and reproductive options
beforehand
Options for carriers
 Depend
on personal choices
 Cultural, religious, family and societal inputs
 Depend on availability of genetic and prenatal
services.
Management of pregnancy

Important to co-ordinate services of obstetrician,
anesthetist and hematologist and to keep patient
and her family informed

Factor level measurement at 34 weeks (Factor VIII
levels may rise but not F IX) informs safety of
invasive procedures in mother (eg epidural)

Knowledge of the gender of the fetus from
ultrasound prepares obstetrician (and parents who
wish to know) for delivery options
Management of delivery
 Multidisciplinary
planning including factor
support…WRITE THAT PLAN…
 Delivery in a centre of obstetric expertise
 Avoidance of invasive fetal monitoring
 Avoidance of instrumental delivery
 Vaginal vs Caesarean,
and read the latest debate in Haemophilia!!
Management of the newborn
 Neonatal
review for boys at risk
 Heightened suspicion for bleeding including
intra-cranial hemorrhage and early
investigation
 Timing of testing for hemophilia
 Preparation for procedures e.g. circumcision
Use of DDAVP in pregnancy in
symptomatic carriers of FVIII
deficiency

Prescribers’ Information advises precaution in
pregnancy and contra-indication in lactation

Intermittent use to cover procedures in first and
second trimesters of pregnancy has not been
associated with harm to pregnancy or fetus

Has been used safely to support epidural blockade

Post partum use of DDAVP or factor
replacement in von Willebrand disease is
recommended to reduce post-delivery fall in
vWF/FVIII levels which usually occurs in the
first week but may be delayed

Ensure that mother does not become
hyponatremic with DDAVP
Support for Carriers

Needs recognition and management by
clinicians

Should be an important issue for program
development by national hemophilia societies

World Federation of Hemophilia resources for
clinicians and carriers available at www.wfh.org
Many helpful sites for
clinicians too
MASAC Recommendation #192
MASAC GUIDELINES FOR PERINATAL MANAGEMENT OF WOMEN WITH
BLEEDING DISORDERS AND CARRIERS OF HEMOPHILIA A AND B
National Hemophilia Foundation, USA, 2009
The main message is to liaise with all “interested” parties (especially the
patient and her family)…and have a written plan
Prince Leopold says

Please encourage
your daughters,
sisters and anyone
else in your family
who may be a
carrier to learn
about hemophilia
and have her factor
level measured
THANKYOU