Turner syndrome is a chromosomal abnormality linked to the total or partial absence of the X chromosome. Its prevalence is 1/2500 female newborns. It constantly associates a stature delay and ovarian failure, with an increased risk of various malformations. The objectives of this study are to show the importance of the cytogenetic study in the management of patients with delayed height and / or primary amenorrhea, and to search for a possible correlation between cytogenetic abnormalities and the clinical expression of Turner syndrome.
Patients and methods
We report the medical observations of two patients followed at the medical genetics department of the Ibn Rochd University Hospital in Casablanca for Turner syndrome, with a mosaic karyotype, carrying a structural anomaly and a monosomy of the X chromosome.
Results and discussion
Stature delay and primary amenorrhea were the indications for the achievement of the constitutional karyotype. There are other circumstances in which Turner syndrome is discovered : prenatal on ultrasound signs, at birth in cases of lymphedema, or in adulthood in case of infertility. In addition to the delay in height, the clinical examination may find in 2/3 of cases a non-specific facial dysmorphia, as well as other associated anomalies, mainly coarctation of the aorta, which can be associated with arterial hypertension. or left heart failure in the perinatal period. The typical karyotype is characterized by a homogeneous X monosomy (45, X), but this cytogenetic type accounts for only 42 to 48% of the chromosomal abnormalities described in Turner syndrome. The homogeneous structural abnormalities of the X chromosome are found in 20 to 25% of cases, and the mosaic karyotype is responsible for 25% of cases, and it consists of a normal cell population and a cell population carrying a monosomy of the chromosome X. The originality of these two observations is that the cytogenetic study revealed a mosaic Turner syndrome, consisting of in the two reported cases of two abnormal cell populations, one carrying an anomaly in number and the another an anomaly in the structure of the X.
Keywords: Turner syndrome, mosaic, isochromosome, stature delay, primary amenorrhea.
22 May 2021 - 26 May 2021