Double Aneuploidy 48,XXY,+21 Associated with a Congenital Heart Defect in a Neonate

Down-Klinefelter Syndrome (48,XXY,+21) in a Saudi Neonate: A Case Report and Literature Review

Aneuploidy is a category of chromosomal abnormalities involving a numerical abnormality of the chromosomes. The most common type seen in live-born babies is trisomy. Double aneuploidy that leads to trisomy of two different chromosomes occurs due to accidental meiotic nondisjunction events; both can have the same or a different parental origin. Other frequently found double aneuploidies include 48,XXX,+21; 48,XXY,+18, and 48,XXX,+18. Here, we report the case of double aneuploidy (Down-Klinefelter syndrome) in a Saudi newborn with the clinical features of Down syndrome, along with hypothyroidism and congenital heart disease, who was admitted to our neonatal intensive care unit. To our knowledge, this is the first case of its kind reported from the Kingdom of Saudi Arabia.

Double aneuploidy 48,ХХХ,+21 of a Bulgarian newborn with Down phenotype: a case report

Background

Aneuploidy is one of the most important chromosomal aberrations, which involves an abnormal number of the chromosomes. Trisomy 21 (Down syndrome) and numerical aberrations of the sex chromosomes have a relatively high prevalence in the general population. However, the patients usually have one of the above genetic disorders and combined cases of two different trisomies are unusual.

Case presentation

We report a case of a patient with double aneuploidy—a combination of trisomy 21 and triple X syndrome. The proband had typical features of Down syndrome and did not manifest any symptoms of polysomy X. The patient had hypotonia, a cardiac defect, and an annular pancreas. A clinical diagnosis of Down syndrome was established, but the cytogenetic analysis found two free full trisomies—trisomy 21 (Down syndrome) and triple X.

Conclusion

Cases of double aneuploidy, combining trisomy 21 and trisomy of a sex chromosome, could be challenging because the patients manifest only symptoms, typical for Down syndrome. The discovery of a second complete free trisomy X in our case was an incidental finding. This illustrates the importance of the cytogenetic analysis, despite the evident phenotype of trisomy 21.

Double Trisomy 48,XXY,+21 in a Neonate with Congenital Heart Disease

Double trisomy 48, XXY, +21 or Down-Klinefelter syndrome is a rare occurrence and presents clinical manifestation of trisomy 21 in early life and of Klinefelter syndrome after 10 months of age. The phenotypic and karyotyping characteristics of a 2-month-old boy were reported. He had mild clinical feature of Down syndrome and echocardiographic features of atrioventricular (AV) septal defects with severe pulmonary valve stenosis.

A Rare Double Aneuploidy Case (Down-Klinefelter)

Down's syndrome has its own dysmorphic findings and is accompanied by mental retardation and hypotonia. Klinefelter's syndrome is a syndrome caused by a numerical abnormality that affects male physical and cognitive development. This case reports a unique finding of 48,XXY, + 21 and a current literature review. A 4-month-old male patient presented with typical clinical features of Down's syndrome with hypothyroidism, atrial septal defect, ventricular septal defect, and patent ductus arteriosus without any phenotypic signs of Klinefelter's syndrome.