GeNeViSTA Genetic Counseling of Prenatally Detected Sex Chromosome Anomalies Haseena Sait, Shubha R Phadke Department of Medical Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India, 226014 Correspondence to: Dr Shubha R Phadke Email: [email protected] Abstract: genetic counselor in terms of counseling and dilemma for the family. The outcome varies greatly Prenatal screening tests are being universally from normal phenotype to those with significant employed in the current era to identify women phenotypic abnormalities. Individuals with SCA at risk of fetal aneuploidies. This unveils usually do not have significant intellectual a high proportion of unanticipated findings disability. Hypogonadism and infertility remain the amongst which sex chromosome abnormalities major issues; both of which have solutions in are frequently encountered. It is imperative that the form of hormone replacement therapy (HRT) geneticists and fetal medicine specialists have and assisted reproductive techniques (ART). The sufficient knowledge about these anomalies in difficulties in decision making are obvious as order to provide appropriate genetic counseling uncertainties about the phenotype are not strong and assist the couples in decision making during enough to consider termination of pregnancy. pregnancy. In the article, we briefly discuss the The decision depends upon parents’ family outcomes and counseling approach for the history and their perspectives to look at the prenatally detected common sex chromosome problem. The parents’ thinking gets influenced abnormalities. by what is conveyed to them by health care professionals involved in prenatal diagnosis and Keywords: Sex chromosome anomalies, prenatal counseling. Hence, it is essential that accurate and screening,Turner syndrome, Klinefelter syndrome, up-to-date information about the likely outcomes genetic counseling. is communicated to the family in a simplified manner. Through this article, we describe the Introduction outcomes of various prenatally detected SCAs and the issues in counseling for the same. Sex chromosome abnormalities (SCAs) are The following case scenarios present some the most frequently encountered chromosomal common problems faced by the clinicians and abnormalities both prenatally and at birth. These families and perspectives in approaching them: are due to the presence of an extra or missing X or Case scenario 1: A 32-year-old G2P1+0L1 mother Y chromosome and most commonly include 45,X; who has a previous child with Down syndrome 47,XXX; 47,XXY; and 47,XYY. The prevalence of (Trisomy 21) visits us at 16 weeks of gestation SCAs is estimated to be around one in 500 for prenatal counseling. After pre-test counseling newborns, twice as common at birth as trisomy regarding the risk of recurrence of 1% for trisomy 21 21. The frequency at prenatal diagnosis is much in the current pregnancy, she opts for prenatal greater and ranges from 1 in 250 to 300 (Linden testing. Amniocentesis followed by quantitative et al., 2002). Though not a primary target for fluorescent polymerase chain reaction (QFPCR) detection in prenatal diagnosis, incidental findings reveals 47,XXY and this finding is confirmed by like SCAs cannot be avoided. With expanding use karyotyping. of population wide screening for chromosomal anomalies by novel genomic technologies like Case scenario 2: A 35-year-old G3P0+2, with non-invasive prenatal screening (NIPS), such previous two abortions, presents with history of two problems will be more commonly seen in the near IVF (in vitro fertilisation) failures and consults us in future. Being an unexpected finding in prenatal view of non-invasive prenatal screening (NIPS) test testing, SCAs pose significant challenge to the showing high risk for monosomy X. This finding is Genetic Clinics 2021 | July - September | Vol 14 | Issue 3 14 GeNeViSTA confirmed by chromosomal analysis from amniotic the occurrence of SCAs is a random event; fluid. Ultrasonography evaluation at 18 weeks is incidentally detected sex chromosome normal. • aneuploidies are more often associated with Case scenario 3: A 30-year-old G3P2 mother with • normal to mildly affected phenotypes than previous two healthy children, visits us at 17 weeks postnatally detected SCAs (Pieters et al., for counseling regarding high risk for trisomy 21 2011); (1:151) on quadruple marker testing. Pre-test the possibility of spontaneous abortion of counseling is provided. Options of NIPS and invasive pregnancy especially in fetuses with 45,X testing are given and she opts for invasive testing. • should also be mentioned; Amniocentesis followed by QFPCR and karyotype is variability in the phenotype of the condition suggestive of 47,XXX chromosome complement. can exist and the inability to provide a precise Counseling for the above-mentioned cases • individual prognosis must be discussed; requires in-depth knowledge about the clinical phenotypes of SCAs, variability in presentation uncertainty and complexity in providing and availability of management options for counseling in case of mosaicism for SCAs hypogonadism and infertility. As these situations • should be discussed; are not infrequent, it is important that role of other autosomal genes and clinical geneticists, fetal medicine specialists and environmental factors altering a child’s counselors acquire adequate knowledge to • prognosis should be stressed upon; provide prospective parents with sufficient and unbiased information regarding these SCAs and written material providing comprehensive guide them in decision making. information about the relevant karyotype will • be useful; Pre-test Counseling if possible, showing selected photographs of individuals with SCAs and talking to other Pre-test counseling for prenatal procedures • parents of children with SCAs can be done for varied indications should always reassuring and helpful; include discussion about the various disorders finally, the issue of disclosure ofSCA which can be detected by the test. A brief diagnosis by parents to others and the discussion on the outcome of these disorders • consequences of the same should be in general which would result in mental addressed at the time of diagnosis; or physical abnormalities should be discussed. if the couple decides to continue with The counseling must include the possibility of the pregnancy, they should be adequately detection of unrelated abnormalities including • counseled regarding when and how to SCAs, unbalanced autosomal abnormalities other anticipate the problems and to seek medical than the intended ones, and mosaic forms. Many care; of these may have variable outcomes. Some groups even suggest that obtaining consent from the couple should be informed of couples, as to whether to include or exclude the the available postnatal interventions. The results of these incidental findings, is essential • potential benefit of knowledge of the (Herlihy et al., 2010). condition to facilitate early intervention should be highlighted; and Post-test counseling it is important to be aware that in addition to phenotypic outcome, the obstetric history of Post-test counseling should mainly focus on the • the woman will play an important role in specific disorder which has been diagnosed. The taking decision about the fate of the current following points have to be kept in mind when pregnancy. This can be perceived in the case providing information and counseling to the scenarios discussed above. couples: Apart from the above-mentioned points for couple should be made aware of the general counseling, the major point that has frequency of the condition in the general to be highlighted in the discussion of these • population; SCAs should be its impact on the reproductive Genetic Clinics 2021 | July - September | Vol 14 | Issue 3 15 GeNeViSTA Table 1 The prenatal and postnatal outcome of few of the commonly detected sex chromosome anomalies. 45,X 47,XXY 47,XXX 47,XYY (Morgan, 2007) (Girardin & Van (Wigby et al., (Bardsley et al., Vliet, 2011) 2016) 2013) Prevalence 1:2500-3000 live born 1:500-1000 live born 1:1000 live born 1:1000 live born girls males females males Risk factor None Advanced maternal None None age Prenatal 99% get aborted High rates of preterm No specific No specific outcome spontaneously; deliveries; no specific antenatal antenatal increased nuchal antenatal malformations malformations translucency (NT), malformations cystic hygroma or hydrops Intelligence Normal but 15-20 Normal but 15-20 Normal but 15-20 Normal points below controls points below controls points below and siblings and siblings controls and siblings Characteristic Short stature (>95%), Tall stature, small Tall stature Tall stature, features webbed neck, low testes, gynecomastia macrocephaly, posterior hairline, in late puberty, macrodontia, narrow palate with sparse body hair scoliosis crowded teeth, broad chest with widely spaced nipples, cubitus valgus, multiple pigmented nevi Associated Cardiac Diabetes, metabolic Rare Hand tremors or abnormalities malformation syndrome, other (coarctation of aorta osteoporosis and involuntary or bicuspid aortic cardiovascular movements valve in 75%) diseases in (motor tics), sensorineural adulthood seizures, and hearing loss, asthma recurrent otitis media, renal malformation (e.g., horseshoe kidney, duplicated or cleft renal pelvis), autoimmune thyroiditis, celiac disease, scoliosis Development At risk of mild delay Reduction in speech, Mild motor delay, At risk for mild in acquiring language abilities,