Indications for chromosome analysis in clinical genetics

Chromosomal analysis

• prenatal
• postnatal

Indications for prenatal analysis of chromosomes

• advanced maternal age
• higher than 35 ys in the date of delivery (increased risk of chromosomal aneuploidies, namely M. Down)
• positive screening of congenital anomalies (1st or 2nd trimester maternal serum screening test + increased NT - higher risk of chromosomal abnormalities)
• positive family history
• affected child/fetus in previous pregnancy (with chromosomal abnormality)
• parent - carrier of balanced chromosomal aberration (e.g. translocation)
• patological or atypical ultrasound finding (IUGR – intrauterine growth retardation, microcephaly, hyperechogenic bowel, hydronephrosis, Fallot tetralogy, club foot, polyhydramnios/oligohydramnios, hygroma colli cysticum,...)
• important for differential diagnosis (ultrasound finding could be solitary – usually without chromosomal abnormality or syndromologic – in many cases caused by chromosomal abnormality)
• others (e.g. mother after chemotherapy, in vitro fertilisation pregnancy, …)

Indications for postnatal analysis of chromosomes

1. children:
   • craniofacial dysmorphy (flat occiput, epicantus, hypertelorism, cleft lip, cleft palate, malformed ears, craniosynostosis, macroglossia,...)
   • congenital anomalies (heart defects, cryptorchism, NTD – neural tube defects, urogenital defects, agenesis corpus callosum,...)
   • psychomotoric retardation
   • developmental delay, failure to thrive
   • growth retardation, short stature
   • hypotonia
2. puberty:
   • amenorhoea
   • gynecomastia
   • developmental defects of secondary sexual features
3. adults:
   • infertility/sterility
   • recurrent spontaneous abortions
   • abnormal spermiogram in men
   • positive family history (reproduction loss, affected child, chromosomal aberration in relatives,…)
   • gamete donors