29 Med. Sci. & L. 1 (1989)

handle is hein.journals/mdsclw29 and id is 1 raw text is: 


Med. Sci. Law (1989) Vol. 29, No. 1 Printed in Great Britain


Editorial


C. M.  JAMES, G. C. JENKINS AND A. D. STEPHENS


SICKLE   CELL  TRAIT
Sickle cell trait is one of  the haemoglobin-
opathies, a group  of inherited defects in the
quantity and quality of haemoglobin  synthesis.
They are found predominantly in people who are
not of northern European extraction, and patho-
logists will increasingly encounter these condi-
tions at post mortem.  Their  influence on the
cause of death will become relevant in forensic
cases.
  Sickle cell trait occurs when  an  abnormal
haemoglobin  gene  is inherited from one parent
and a normal  haemoglobin  gene from the other
parent. This  results in a mixture  of normal
haemoglobin   (HbA)   and  sickle haemoglobin
(HbS)  being produced. Sickle haemoglobin  is a
variant of haemoglobin formed by an amino acid
substitution in the beta chain. This disrupts the
structure of the haemoglobin molecule so as to
cause crystallization when the red cell is stressed
by hypoxia, acidosis, high oncotic pressure or a
combination  of the three. This crystallization,
which is initially reversible, causes the character-
istic sickling of the red cells.
  Sickle haemoglobin   is found  in Equatorial
Africa, India, Southern Turkey,  Saudi Arabia,
Sicily, Cyprus and Greece.  It is also found in
areas to  which these  people have  emigrated,
notably the West  Indies, the United States and
Great  Britain. The  geographical incidence of
sickle cell trait in the UK varies widely and it is
becoming   increasingly common   in our  major
cities. Its incidence in the UK has been reported
at 3.3%   of blacks (Brozcovic  and  Anionwu,
1984). A  screening programme  in Hackney  has
shown  an incidence of over 12%  for sickle cell
trait in the child-bearing population. In the USA
the incidence has been reported in a number of
studies and is about 8% of blacks and 0.08% of
non-blacks (Myerson  et al, 1959).
  Sickle cell anaemia (HbSS) is the homozygous


state for haemoglobin  S and  people with this
condition are liable to considerable morbidity
and  mortality. Sickle cell disease is the name
given to a group of inherited conditions having
similar clinical consequences   to sickle  cell
anaemia,  but which are due  to different geno-
types such as SS, SC,  SD,  SO, S/Beta  thalas-
saemia,  S/Hereditary   Persistence of  Foetal
haemoglobin  (S/HPFH).
  The  most common  question asked of a forensic
pathologist in these cases must be whether the
possession of  sickle cell trait contributed to
death. Defence counsel may attempt to show that
the haemoglobinopathy   was, at least partially,
responsible for the death of, for instance, the
victim of an assault. There has been much con-
flict in the literature on this point.
  Undoubtedly   some  of the early reports sug-
gesting a strong association between death and
sickle cell trait were based upon patients who
may  well have had the much  more  serious con-
ditions of sickle cell disease - sickle C disease,
sickle D disease, sickle 0 disease or sickle-beta
thalassaemia -  the exact diagnosis often being
made   on empirical  grounds before  diagnostic
haemoglobin  electrophoresis was available.
  Epidemiological surveys have revealed no re-
duction in the incidence of sickle cell trait with
increasing age, suggesting that there is no excess
mortality associated with the condition. In addi-
tion surveys of post mortems in those with sickle
cell trait have shown no difference in the mean
age of death between those with sickle cell trait
and  normal controls. A twelve-year longitudinal
survey of 119 Jamaican adults with sickle cell trait
and 856 control subjects showed no difference in
mortality rates between the two groups (Ashcroft
and  Desai, 1976). A study of  120 autopsies in
those with sickle cell trait compared with 1,104
normals showed  no difference in the mean age of
death between  the two groups (McCormick   and


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