Can a healthcare provider order karyotyping or refer to a genetic specialist?

Can Healthcare Providers Order Karyotyping or Refer to Genetic Specialists?

Yes, healthcare providers can and should order karyotyping or refer to genetic specialists when clinically indicated, provided they possess minimum competencies in genetic evaluation, or they should directly refer to genetics professionals when these competencies are lacking.

Provider Qualifications for Ordering Genetic Testing

According to the American College of Medical Genetics and Genomics (ACMG), a clinician can order genetic testing including karyotyping if they meet specific minimum knowledge requirements 1:

• Ability to perform basic clinical genetics evaluation including family history, genetics-focused medical history and physical examination, and critical summary of prior genetic evaluations 1
• Ability to determine whether karyotyping is the appropriate test for the specific clinical indication, considering other available tests (including genomic and non-genomic tests), the patient's age, and cognitive ability 1
• Ability to provide adequate pre-test counseling, including informed consent for primary and secondary findings 1
• Ability to interpret results and provide post-test counseling, or seek input from a genetics professional for this step 1

When to Refer to Genetic Specialists

Direct referral to genetics professionals is recommended when providers lack the above competencies or when clinical scenarios are complex 1. The ACMG guidelines emphasize that genetic testing should be accompanied by consultation with a genetics professional and adequate genetic counseling 1.

Specific Indications for Genetic Referral and Karyotyping

Neonates and Children:

• Children born to parents with known chromosomal abnormalities or rearrangements (balanced or unbalanced), especially with dysmorphic features and/or cognitive impairment 1
• Unexplained mental retardation or global developmental disorder 1
• Multiple major and/or minor congenital anomalies 1
• Dysmorphic features not familial, especially when accompanied by developmental delay or mental retardation 1
• Unexplained intrauterine growth retardation to rule out chromosomal or syndromic diagnosis 1
• Congenital hypotonia or hypertonia to rule out chromosomal, metabolic, or syndromic diagnosis 1

Adults:

• Recurrent pregnancy losses (more than 2) to rule out chromosomal rearrangements such as balanced translocations or inversions, which cause 5-7% of recurrent pregnancy losses 1
• Abnormal sexual maturation or delayed puberty to rule out intersex conditions, chromosomal abnormalities, or syndromic diagnoses 1
• Tall or short stature for genetic background to rule out skeletal dysplasia, chromosomal or syndromic diagnosis 1

Practical Considerations

Diagnostic Yield

Research demonstrates that karyotyping in prenatal samples with molecular or metabolic referrals yields abnormal results in approximately 3.8% of cases, including 2.4% with uncertain significance 2. This supports selective rather than universal karyotyping based on clinical indications 2.

Common Pitfalls to Avoid

• Do not assume all providers have adequate genetics training: Primary care providers and specialists may have limited knowledge regarding genetics and genetic tests 1. When in doubt, refer to genetics professionals 1.
• Avoid directive counseling: Nongeneticist providers tend to be directive in reproductive decision-making situations, which may not align with patient autonomy 1
• Ensure adequate time for counseling: Proper informed consent for genetic testing requires more than 1 hour 1, which may exceed typical appointment times for non-genetics providers
• Consider targeted testing first: When specific phenotypes suggest known genetic conditions, targeted gene panels may be more appropriate than karyotyping 1

Testing Algorithm

The recommended approach follows this hierarchy 1:

1. If phenotype is specific to a known genetic condition with optimized genetic panel testing available → order targeted gene panel first 1
2. If phenotype is nonspecific and family history does not indicate X-linked or autosomal recessive inheritance → consider chromosome microarray analysis before karyotyping 1
3. If clinical scenario is complex or family history is complicated → refer directly to genetics specialist 1