Diagnosis:
Possibly in-utero (ultrasound/amniocentesis), at birth by physical
characteristics, pre-school entry by growth failure and
subsequently by delay of puberty
Treatment: GH,
anabolic and sex steroids (& combinations of these)
Females normally
have two X-chromosomes. The lack, partial lack, or abnormal
formation of the second X chromosome produces the condition called
Turner Syndrome. It is one of the most common chromosome disorders
and occurs in 1 in 2500 live female births.
Girls with
Turner Syndrome have normal intelligence, though in some cases it
is associated with specific learning difficulties. They also have
short stature with or without some physical characteristics such
as puffy hands and feet soon after birth, webbing of the neck,
broad chest, small nipples and characteristic face. Bone age is
delayed only slightly or not at all.
The diagnosis is
confirmed through examination of the chromosomes from blood cells
(karyotype) and occasionally other body tissues such as skin. In
early childhood, feeding difficulties may occur as well as
frequent ear infections.
Short stature is
the most common feature of Turner Syndrome and girls with this
syndrome are often slightly small at birth. The average adult
height is about 147cm, although a few may reach 152cm (5ft.
2ins). Parental height plays the most important role in
determining the adult height of girls with Turner Syndrome and a
girl with tall parents is likely to be taller than a girl with
short parents.
Lack of sexual
maturation during adolescence is another feature of Turner
Syndrome. This occurs in the majority of girls because the ovaries
do not develop normally to produce oestrogen. The missing, or
abnormal, X chromosome affects ovarian function and this has to be
explained to the parents and child.
Although growth
hormone secretion is nearly always normal, many studies have
demonstrated that by giving additional growth hormone, there is a
dramatic increase in growth rate and GH treatment is licensed for
the treatment of short stature in girls with Turner Syndrome. The
increase in final stature is variable and is dependent on the age
of starting treatment. The mild anabolic steroid, oxandrolone, in
combination with growth hormone, is under investigation, as is the
optimum age to start low doses of oestrogen treatment.
At the
appropriate age, girls with Turner Syndrome are given oestrogen
replacement therapy, in gradually increasing doses, to stimulate
breast and pubic hair development. In due course regular uterine
withdrawal bleeds that are important for keeping the uterus
healthy are introduced and girls with Turner Syndrome commonly
wish to start their periods at the same time as their friends.
These withdrawal bleeds can be produced by giving oestrogen and
progestogen for 3 weeks, followed by a week without treatment. It
is important that these girls, and their parents, understand that
the uterus and vagina are normal and so with the new techniques of
in-vitro fertilisation (“test-tube”), and with an egg donated from
another woman, there is the potential for fertility.
The previous
page describes the situation in the full Turner Syndrome karyotype,
written XO. Sometimes, only a proportion of cells has this
chromosome compliment, the remaining cells have the normal female
XX chromosomes. This condition is referred to as Mosaic Turner
Syndrome. Girls with mosaic forms of Turner Syndrome often have
fewer of the physical features and may be more likely to show
signs of sexual development without treatment, although they are
unlikely to develop fully and to menstruate. The extent of the
short stature, however, is not related to the specific karyotype.
It follows that any girl with short stature of unknown
cause should have a chromosome analysis done.
