Chromosomal Abnormalities in Jacobs and Turner Syndromes

Introduction to Jacobs Syndrome

The European Association of Urology recommends that males with a 47,XYY karyotype, characterized by an extra Y chromosome, should be evaluated for potential fertility impairment and male hypogonadism 1.
Males with 47,XYY typically present with normal male external genitalia and may go undiagnosed unless fertility issues or other concerns prompt karyotype analysis, as suggested by the European Urology guidelines 1.
The American College of Medical Genetics and Genomics recommends that array-based testing should be used with caution, as it may miss XYY syndrome if the wrong gender control is used, highlighting an important technical limitation of chromosomal microarray analysis 2, 3.
The American Urological Association recommends that karyotype testing should be recommended for males with primary infertility and azoospermia or sperm concentration <5 million sperm/mL when accompanied by elevated FSH or testicular atrophy, as a diagnostic approach for Jacobs syndrome 4, 5.

The American College of Medical Genetics and Genomics states that Turner syndrome is characterized by complete or partial absence of one X chromosome (45,X karyotype) in phenotypic females, resulting in short stature and gonadal dysgenesis, with mosaic forms such as 45,X/46,XX mosaicism presenting with variable phenotypic severity 6.
Noninvasive prenatal screening (NIPS) for monosomy X has a positive predictive value of only 29.5%, lower than other sex chromosome aneuploidies, partly due to higher rates of placental mosaicism and maternal mosaicism for 45,X, according to the Genetics in Medicine guidelines 6.

The National Comprehensive Cancer Network recommends that the presence of Y chromosome material in 45,X/46,XY mosaicism confers significant gonadoblastoma risk, particularly in individuals with gonadal dysgenesis, with a risk exceeding 40% in individuals with 46,XY karyotype and gonadal dysgenesis 7, 8.
Prophylactic gonadectomy is generally recommended for dysgenetic gonads in 45,X/46,XY individuals, particularly those raised female or with intra-abdominal gonads, although this is not explicitly stated in the provided citations, it is a common recommendation in the medical community 7, 8.

The American College of Medical Genetics and Genomics recommends that conventional karyotyping remains superior to chromosomal microarray for detecting sex chromosome aneuploidies when rapid diagnosis is needed or when specific aneuploidies are suspected, highlighting the importance of karyotype analysis in diagnosis 2, 3.