Tag Archives: #SexChromosomalAbnormalities

45,X (Turner Syndrome)

 © 2018, GENASSIST, Inc.

By Keith S. Wexler, MBA, Maternal Fetal Medicine, Prenatal Diagnosis and Biotech/Life Sciences Consultant, GENASSIST, Inc.

Paul Wexler, M.D., F.A.C.O.G., Medical Director, GENASSIST, Inc.

Clinical Professor, Department of OB/GYN, University of Colorado Health Sciences Center

Clinical Professor, Division of Genetics/Dept. of Pediatrics, Univ. of Colorado/The Children’s Hospital

The breakdown of fetal cells in the maternal circulation make it possible for laboratories to screen for Fetal DNA during pregnancy.

When fetal cells break down Cell Free DNA (cf DNA) is released. It is possible to duplicate many copies of this DNA so that testing is possible. This prenatal non-invasive testing can be performed as early as the 10th week of pregnancy.

45X – Turner Syndrome is characterized by a missing X chromosome in females instead of the expected two X chromosomes.

http://www.turnersyndromefoundation.org/

If a Maternal Fetal DNA test result comes back as “High Risk” for a chromosomal abnormality, the recommendation(1) is to confirm the diagnosis by amniocentesis.

Ultrasound performed in pregnancy after 15 weeks gestation can help identify some babies with 45X.

45X Ultrasound “Markers”:

  • Increased Nuchal Translucency – NT
  • Cystic Hygroma
  • Micrognathia (small jaw)
  • Short 4th metacarpal
  • Differential diagnosis: Noonan Syndrome
  • Differential diagnosis: 4p+ Syndrome

(1)The American College of Obstetricians & Gynecologists, Committee Opinion Number 545 December 2012, Publications Committee, “NonInvasive Prenatal Testing for Fetal Aneuploidy”.  The American College of Obstetricians and Gynecologists Committee on Genetics, The Society For Maternal-Fetal Medicine

 

47,XXY (Klinefelter Syndrome)

© 2018, GENASSIST, Inc.

By Keith S. Wexler, MBA, Maternal Feta Medicine, Prenatal Diagnosis and Biotech/Life Sciences Consultant, GENASSIST, Inc.

Paul Wexler, M.D., F.A.C.O.G., Medical Director, GENASSIST, Inc.

Clinical Professor, Department of OB/GYN, University of Colorado Health Sciences Center

Clinical Professor, Division of Genetics/Dept. of Pediatrics, Univ. of Colorado/The Children’s Hospital

47,XXY (Klinefelter Syndrome) is characterized by two X chromosomes and one Y chromosome in males instead of the expected one X and one Y chromosome.

Maternal Fetal DNA testing is Not absolutely diagnostic and testing does Not distinguish mosaicism.

Approximately 80% of male fetuses with a 47,XXY male karyotype show no mosaicism and 20% of males with 47,XXY demonstrate mosaicism.

The finding of normal cells with a 46,XY karyotype in addition to 47,XXY cells might reduce the impact of the 47,XXY karyotype but is not assured to do so.

The incidence of 47,XXY males in the general population is approximately 1:500 to 1:1000 live births.

47,XXY (Klinefelter Syndrome) males may show:

  • Accelerated height beginning at approximately 5-6 years of age with an average adult height of 6’3”
  • Problems with behavior and anger management
  • Mild developmental delay, although often intelligence is normal
  • Acne
  • Small testes
  • Decreased fertility with decreased or absent sperm
  • Gynecomastia (breast development) at puberty (10-12% of children)
  • Less muscular development
  • Decreased facial hair

Testosterone therapy may be recommended.

Spontaneous pregnancies and pregnancies achieved with assisted reproductive technologies are possible especially with males with mosaicism.

Sperm numbers have been reported to decrease with age and possibly testosterone.

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