Book reviews

Journal of Medical Genetics, 1979, 16, 238-244

Medical Genetic Studies of the Amish.
Selected Papers
By V. A. McKusick. (Pp. x + 525; Figures +
Tables. £19-25.) Baltimore and London:
Johns Hopkins University Press. 1978.

To read this edited collection of papers is both a
fascinating experience and, for one already familiar
with the Amish, a pleasurable reminder of the
persistence and success of their remarkable way of
life in 20th century America. A visitor to the Moore
Clinic at Johns Hopkins Hospital in the late 1960s
might have been excused if he had thought that the
Amish formed a majority of the Baltimore popula-
tion, but this book shows clearly how worthwhile the
intensive study of this group has proved in both
medical and population genetics.
The papers are reproduced unchanged, but their

value is greatly increased by the addition of notes on
subsequent developments. They are grouped into
those dealing with general and population genetics,
studies of previously recognised Mendelian syn-
dromes, and (the largest section) 'new recessively
inherited entities, many of which would have been
difficult, if not impossible, to recognise outside the
setting of a defined, closed, and well documented
community as provided by the Amish'. Among these
delineations of new disorders, that of 'cartilage hair
hypoplasia' still stands out for its clarity and its
masterly combination of clinical and genetic
information.
The value of the studies in this book extends far

beyond the demonstration that the disorders in
question are recessively inherited. The range of
clinical expression produced by what clearly must
be a single gene is something that is difficult to
document in the more heterogeneous patients seen
in most populations. The studies of autosomal
recessive limb-girdle muscular dystrophy and of the
'Troyer syndrome' provide excellent examples of
this. Another particularly impressive feature of the
Amish studies is the detail and accuracy of the
genealogical and demographic work which underlies
them, much of it due to the attachment of Amish
people themselves to this type of documentation. It
is of interest that a number of the main contributors
to the book are themselves of Amish origin, and it is
fortunate that the Amish antipathy to further
education has not prevented the emergence of those
individuals to transmit the unique aspects of Amish
culture to the world in general.

Anyone working in medical genetics to whom the
Amish are unfamiliar should read this book without
delay; it will be a revelation as to the value of
studying genetic isolates. Those who do know of the
Amish will not need encouragement to refresh their
memory of the subject and gain new ideas. It should
also serve as a stimulus for people to study their own
equivalents of the Amish. Though few of us have
access to such an ideal population, there are many
minority groups which would repay much closer
investigation, where studies of genetic diseases have
not been attempted. Many of these groups, less
robust than the Amish, may soon disappear for ever
if the opportunity is not taken soon.

P. S. HARPER

British Medical Bulletin: The HLA System
Vol. 34, No. 3, September 1978. Scientific Editor,
W. F. Bodmer. (Figures + Tables. £5O00.)
London: The British Council. 1978.

Medical journals are now replete with articles on
HLA and, though weary voices have been heard to
exclaim 'not HLA again', we should take heart.
Cytogenetics had similarly inauspicious beginnings
when, 20 years ago, pictures of 'squashed spiders'
began to appear in medical journals. There are many
aspects of HLA which are relatively simple, though
others seem comprehensible only to experienced
travellers in the exotic lands of lymphomania. The
latest issue of the British Medical Bulletin provides
an excellent overview of the HLA system and will do
much to enlighten the weary. It is a convenient
introductory package for this fascinating genetic
system. I recommend reading 'Evolution and
Function of the HLA System' at an early stage as, in
it, central issues relating to the system are dealt with
succinctly and comprehensibly. The other articles
can be divided into several categories. Firstly, the
'technology' of HLA: serology, cellular typing, the
chemistry of HLA antigens, and the 'new' HLA-
DRW locus are considered in 4 articles. Secondly,
the role of HLA as part of the major histocom-
patibility system (MHS) is discussed in 2 articles
devoted to complement genetics and to the immune
response. Thirdly, the somewhat variable importance
of HLA in human organ transplantation is described
objectively. The fourth category, that of the associa-
tion between HLA and various diseases, takes up a
large part of the Bulletin in a total of 8 papers

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