OP-11 Prenatal diagnosis of a fetus with 45,X47,XYY mosaicism

Objective

45,X/47,XYY mosaicism is quite rarely reported in fetuses, children and adults. Therefore, the true prevalence of the condition is still not well documented.[1] The first case was described by Jacobs et al. in 1961.[2] It is considered to be a type of mixed gonadal dysgenesis and most of the cases are diagnosed postnatally. The phenotype is highly variable ranging from Turner stigmata to normal male. Sonographic phenotypic characteristics are usually too subtle to identify making the condition difficult to diagnose prenatally. Although ambiguous genitalia signs such as cliteromegaly, labial fusion, hipospadias, micropenis may be the major findings, some other associated anomalies like increased nuchal translucency or hypoplastic nasal bone have been reported.

 Case

27 years old mother with her fourth pregnancy after an abortion and a termination because of body stalk anomaly was referred for counselling due to an increased combined risk of for Trisomy 21. No other significant maternal risk factor except for iron, vitamin D, folate deficiency, history of nephrolithiasis, recurrent urinary tract infections and group B streptococcus carriage was detected. Ultrasound scan at 17 weeks revealed shortness of fetal femur, bilateral choroid plexus cysts and hyperechogenic bowel. Prenatal diagnosis via amniocentesis was offered and the parents accepted the procedure.

 Results

Second trimester fetal anatomic scan at 22 weeks detected increased nuchal fold thickness, cardiac left ventricular echogenic focus, muscular ventricular septal defect and relative micrognathia in addition to aforementioned findings (Figure1). QF PCR Analysis of amniotic fluid for 13, 18, 21, X, Y chromosomes determined 35% X0, 14% XYY mosaicism. Definitive karyotype analysis accordingly confirmed 45,X0/47,XYY mosaic chromosomal pattern. The parents were provided with detailed and extensive genetic - prognostic counselling and finally opted for the termination of pregnancy at 23rd week. Feticide was performed and 450 gr externally normal male fetus was delivered subsequently. Parental karyotype analysis was later revealed to be normal.

 Conclusion

Coexistence of several prenatal minor sonographic fetal findings and elevated trisomy risks of standard serum biochemical tests should lead to further evaluation of the pregnant patient. Keeping in mind the relative lower sensitivity of non-invasive prenatal tests for gonosomal anomalies, the option of invasive prenatal diagnostic procedures may be offered to parents after satisfactory genetic counselling. Some of these subtle signs may come out as rare karyotype abnormalities of varying severity and significance. 

Keywords

Genetic, ultrasound, prenatal diagnosis, syndrome

1. Ostrow V, De Luca F. Long term follow-up of a child with ambiguous genitalia, mixed gonadal dysgenesis, and unusual mosaicism. J Pediatr Endocrinol Metab. 2009 Sep;22(9):863-6.
2. Jacobs PA, Harnden DG, Buckton KE, Brown WM, Kıng MJ, Mcbrıde JA, Macgregor TN, Maclean N. Cytogenetic studies in primary amenorrhoea. Lancet. 1961 Jun 3;1(7188):1183-9.  
3. Lin CY, Wang PH, Yang MJ, Chen CY. A case of 45,X/47,XYY mosaicism in a male fetus with a hypoplastic nasal bone. J Ultrasound Med. 2015 Feb;34(2):353-4. 

	File/Dsecription
	Figure 1
	Figure 2