Understanding Sperm DNA Fragmentation (SDF) and Karyotyping

31st July 2025/in Knowledge Hub, Pregnancy, Trying To Conceive/by Bryan Beattie

Understanding Sperm DNA Fragmentation (SDF) and Karyotyping in Recurrent Pregnancy Loss and Adverse Pregnancy Outcomes

Sperm DNA Fragmentation (SDF)

This article explains the importance of sperm DNA fragmentation (SDF) testing and karyotyping in couples affected by RPL, infertility, and genetic conditions in pregnancy. It also explores the impact of lifestyle and age-related male factors on reproductive outcomes and summarises current UK and European guidance.

Recurrent pregnancy loss (RPL), poor pregnancy outcomes, and fetal genetic abnormalities are commonly investigated through maternal factors. However, there is now increasing recognition that male factors, particularly sperm DNA integrity and paternal chromosomal abnormalities, may play a significant role.
Male Factor Contribution to Pregnancy Loss and Subfertility

Although historically under-investigated, male factors are now believed to contribute to:
– Up to 40–50% of couples experiencing infertility
– 20–40% of cases of unexplained recurrent pregnancy loss

A standard semen analysis only evaluates sperm count, motility, and morphology. However, it does not assess DNA integrity, which is essential for normal fertilisation, embryo development, and fetal genetic stability.

What Is Sperm DNA Fragmentation (SDF)?

Sperm DNA fragmentation (SDF) refers to structural damage in the DNA carried by sperm. High levels of fragmentation have been associated with:

– Increased risk of recurrent miscarriage
– Reduced embryo quality
– Failed implantation after IVF or ICSI
– Possible increased risk of fetal genetic abnormalities

Causes of Increased Sperm DNA Fragmentation

SDF can be caused by several factors:
– Advanced paternal age
– Smoking
– Obesity
– Excessive alcohol use
– Varicoceles
– Exposure to heat or toxins
– Genital tract infections
– Oxidative stress

What Does SDF Testing Involve?

Sperm DNA fragmentation can be assessed using several laboratory techniques, including:
– TUNEL assay
– SCSA (Sperm Chromatin Structure Assay)
– COMET assay
– SCD (Sperm Chromatin Dispersion)

These tests provide a DNA fragmentation index (DFI) or equivalent score. A high DFI is associated with an increased risk of pregnancy loss, particularly when no female cause is found.

The Importance of Karyotyping

Karyotype testing or chromosome testing is a laboratory test that analyses the number and structure of chromosomes. Structural rearrangements such as balanced translocations, inversions, or sex chromosome abnormalities in either partner can significantly increase the risk of miscarriage or fetal anomalies. Reporting time is typically around 3 weeks.

In couples with recurrent miscarriage, chromosomal abnormalities are found in around 2–6% of cases, more commonly in those with three or more losses.

Karyotyping is especially recommended when:
– There is a history of multiple pregnancy losses
– There has been a pregnancy affected by a chromosomal anomaly
– Embryo development has repeatedly failed or arrested
– There is a personal or family history of genetic conditions

Paternal Age

Advanced paternal age (>40 years) has been linked with:
– Increased sperm DNA fragmentation
– Higher risk of de novo genetic mutations
– Increased miscarriage rates
– Higher risk of neurodevelopmental conditions such as autism and schizophrenia

Lifestyle and Environmental Factors

Lifestyle factors can affect sperm quality and DNA integrity. These include:
Smoking – Increases DNA damage and oxidative stress
Obesity – Disrupts hormone balance and increases ROS
Alcohol – Affects sperm structure and motility
Poor Diet – Reduces antioxidant defences
Stress – Disrupts hormonal regulation
Heat/chemical exposure – Can damage DNA

The Role of Antioxidants in Sperm DNA Fragmentation (SDF)

As oxidative stress is a major contributor to DNA fragmentation, antioxidants are frequently used as a treatment strategy. Common supplements studied include:
– Vitamin C and E
– Zinc and selenium
– L-carnitine
– Coenzyme Q10
– N-acetylcysteine

Cochrane Review (2019) suggests antioxidants may modestly improve live birth and clinical pregnancy rates in subfertile men.

Current Clinical GuidanceRoyal College of Obstetricians and Gynaecologists (RCOG)
Green-top Guideline No. 17: Recurrent Miscarriage (2023 update)
– Recommends parental karyotyping when there are three or more miscarriages
– Notes emerging evidence for sperm DNA damage, not yet recommended for routine use
Full text: http://www.rcog.org.uk/media/mqpkob5r/gtg_17.pdf

European Society of Human Reproduction and Embryology (ESHRE)
– Advises parental karyotyping for unexplained RPL
– SDF testing may be considered where no female cause is found
Full text: https://www.eshre.eu/Guidelines-and-Legal/Guidelines/Recurrent-Pregnancy-Loss.aspx

Summary Table

Investigation | Purpose | When to Offer
————-|———|—————
Sperm DNA Fragmentation Test: Evaluates hidden DNA damage in sperm. Consider if Recurrent miscarriage, poor embryo quality, IVF failure
Karyotype: Detects structural chromosome anomalies. Consider if Recurrent loss, fetal anomalies, infertility
Lifestyle Review: Identifies modifiable risk factors: Consider if All male partners in fertility workup
Antioxidants: May reduce oxidative sperm damage. Consider if High DNA fragmentation, poor semen parameters

Conclusion

Male factors are often under-recognised contributors to reproductive failure and genetic conditions. Sperm DNA fragmentation and chromosomal abnormalities may play a role in up to 40% of RPL cases and are increasingly considered in modern fertility evaluation.

At Innermost Healthcare, we offer:
– Parental karyotyping
– Sperm DNA fragmentation (SDF) testing (by arrangement)
– Personalised male fertility assessments
– Support with lifestyle optimisation and antioxidant supplementation

For more information, visit: https://innermosthealthcare.com

Understanding NIPT and Microdeletions

29th July 2025/in Genetics, Knowledge Hub, Pregnancy/by Bryan Beattie

Understanding NIPT and Microdeletions

What are Microdeletions?

Microdeletions are very small missing pieces of DNA on a chromosome. While large chromosomal differences like Down syndrome involve entire chromosomes, microdeletions affect much smaller regions. Depending on which genes are affected, they can sometimes cause learning difficulties, developmental delays, or other health issues — but this varies widely.

How Are Microdeletions Detected?

Some non-invasive prenatal tests (NIPT) include optional screening for a limited number of microdeletion syndromes. This is done by analysing fragments of placental DNA in the mother’s blood.

Although NIPT is very accurate for detecting common conditions like Down syndrome, it is much less accurate for rare conditions such as microdeletions.

What Microdeletions Can Be Screened?

Condition	Region Affected	Approximate Frequency	Associated Features
22q11.2 deletion (DiGeorge)	Chromosome 22	1 in 4,000	Heart defects, immune problems, learning difficulties
1p36 deletion syndrome	Chromosome 1	1 in 5,000–10,000	Developmental delay, seizures
Cri-du-chat syndrome	Chromosome 5p15	1 in 20,000–50,000	Cat-like cry, intellectual disability
Wolf–Hirschhorn syndrome	Chromosome 4p16	1 in 50,000	Facial features, severe delays
Prader–Willi / Angelman	Chromosome 15q11–13	1 in 10,000–20,000	Feeding problems, behaviour differences

Not all NIPT providers screen for every microdeletion listed here — and some only include them as optional add-ons.

Why Is Screening for Microdeletions Controversial?

• These conditions are extremely rare.

• The tests are prone to false positives.

• Positive Predictive Value (PPV) is low.

• This causes real distress for families.

Should I Screen for Microdeletions?

If you are considering NIPT, you may be offered the option to include microdeletion screening — but it’s worth pausing to consider the pros and cons carefully.

Ask yourself:

“If a test says my baby is at high risk of a rare condition, but there’s a very low chance it’s true – and the ultrasound scan looks completely normal – how will that make me feel?”

For many families, a ‘high risk’ microdeletion result leads to significant stress and anxiety, with invasive testing needed to confirm or exclude the diagnosis. In most cases, the baby turns out to be perfectly healthy.

Unless there is:
– a known family history of a specific microdeletion syndrome,
– or a structural abnormality seen on ultrasound,

…many women choose not to screen for microdeletions, especially given the low accuracy, low PPV, and high emotional burden.

What Happens If a Microdeletion is Suspected?

If your NIPT result suggests a possible microdeletion:
1. You will be referred for counselling with a specialist or genetic counsellor.
2. Further testing such as CVS or amniocentesis may be offered to check the baby’s chromosomes directly.
3. A detailed scan will be reviewed to look for structural abnormalities that may support or challenge the finding.

Summary: What You Should Know

Key Fact	What It Means
Microdeletions are rare	Most pregnancies are unaffected
NIPT is less reliable for microdeletions	Results often need confirmation
High false positive rate	Many ‘high risk’ results are wrong
Low PPV	Even if your result is high risk, baby is very likely to be healthy
Testing can cause anxiety	Consider the emotional impact before deciding
Scans are important	A normal ultrasound reduces the chance of a true condition even further

Final Advice

Before deciding to include microdeletions in your NIPT, it’s worth speaking to your healthcare provider. Think about:
– Your personal or family history
– Whether you’d want further tests if a result came back ‘high risk’
– How you might feel managing uncertainty during pregnancy

You are always in control — and making an informed choice is what matters most.

Understanding NIPT and Sex Chromosome Aneuploidy

29th July 2025/in Genetics, Knowledge Hub, Pregnancy/by Bryan Beattie

Understanding NIPT and Sex Chromosome Aneuploidy

What is Sex Chromosome Aneuploidy?

Sex chromosome aneuploidy (SCA) refers to conditions where there are too many or too few sex chromosomes (X or Y) in a baby’s cells. Normally, females have two X chromosomes (XX) and males have one X and one Y (XY). Changes in the number of sex chromosomes can lead to conditions with varying effects on development, fertility, learning, and physical features.

How is SCA Detected?

Some non-invasive prenatal tests (NIPT) include optional screening for sex chromosome aneuploidies. This is done using a sample of the mother’s blood to analyse placental DNA fragments. While NIPT is highly accurate for common conditions like Down syndrome, the accuracy for detecting SCA is lower.

Common Sex Chromosome Aneuploidies

Condition	Karyotype	Estimated Frequency	Possible Features
Turner Syndrome	45,X	1 in 2,000–2,500 girls	Short stature, infertility, heart/kidney problems
Klinefelter Syndrome	47,XXY	1 in 600 boys	Learning difficulties, infertility, tall stature
Triple X Syndrome or Trisomy X	47,XXX	1 in 1,000 girls	Often no symptoms; sometimes learning/behavioural difficulties
XYY Syndrome or Jacob Syndrome	47,XYY	1 in 1,000 boys	Taller than average, some may have learning difficulties

Should I Screen for SCA?

Many people with SCA live healthy lives and may not be diagnosed until adulthood — or not at all.

It’s important to understand that a ‘high risk’ result from NIPT for a sex chromosome condition often causes significant anxiety, but frequently turns out to be a false alarm. This is especially true when ultrasound scans are completely normal.

What are the Limitations of NIPT for SCA?

• These conditions are often mild or silent, and do not always require medical intervention.

• Positive Predictive Value (PPV) is low — false positives are common.

• Mosaicism and confined placental differences can affect results.

• Follow-up invasive tests may be offered to confirm the result — which carry a small risk.

What Happens If a Sex Chromosome Aneuploidy is Suspected?

If NIPT suggests a possible SCA:
1. You will be offered counselling to explain the result and its uncertainty.
2. Diagnostic testing (CVS or amniocentesis) may be offered.
3. A review of the baby’s scan will help determine if any features support the finding.

Summary: What You Should Know

Key Fact	What It Means
SCAs are not rare	But often have mild or no symptoms
NIPT is less reliable for SCAs	High false positive rate
Low PPV	Many ‘high risk’ results are not confirmed on testing
May cause anxiety	Important to consider emotional impact
Scans may be normal	No visible abnormalities often present

Final Advice

Before choosing to screen for sex chromosome conditions, consider whether knowing this information will help your decision-making. If there is no family history and the scans are normal, many parents choose not to screen for SCAs, especially due to the high false positive rate and uncertainty involved.

As with all prenatal screening, making an informed decision is the most important step.