Prenatal diagnosis and genetic screening : community and service implications / a report of the Royal College of Physicians.

  • Royal College of Physicians of London.
Date:
1989
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Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Prenatal diagnosis and genetic screening : community and service implications / a report of the Royal College of Physicians. Source: Wellcome Collection.

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    Table 1. Approximate annual incidence of births of infants with congenital and genetically- determined disorders in the UK (Total annual births about 700,000). Disorder Annual births per 1,000 Total annual births in the UK Congenitally malformed infants: Sporadic abnormalities 15-20 10,500-14,000 Inherited abnormalities ~ 2 ~ 1,400 Chromosomal disorders: Sporadic (parental chromosome non-disjunctions) 2 1,400 Inherited (familial chromosome rearrangements) 0.6 420 Mendelian single gene defects: Dominant ~ 4 ~ 2,800 X-linked 1-2 700-1,400 Recessive ~ 2 ~ 1.400 TOTAL 27-33 18,600-22,800 Total ‘sporadic’ disorders = 17-22 per 1,000; 65% of total Total inherited disorders = 10-11 per 1,000; 35% of total ‘Multifactorial’ conditions, other than congenital malformations, are not included. Table 2. Incidence of different types of congenital malformations 3 System involved Rate per 10,000 Percentage of all Proportion births malformations correctable Central nervous system 18-50 >10 Very few Eye 3-12 < 2 Some Ear 7 2.6 Some (often minor) Heart 40-96 >20 Many Respiratory system 4 1.4 Some Lip and palate 14 4.9 Most Digestive system 12-38 6.3 Most External genitalia 11-24 5.9 Most Urinary tract 9-16 3.5 Many Limbs Reduction deformity 3-9 1.5 None Other 40-80 20 Many Abdominal wall 5-6 2 Many Other - 19.4 Many not severe TOTAL 287 100 a Based on EUROCAT Study [52] detecting them is to screen pregnant women using mass methods such as routine ultrasound scanning, maternal serum alphafetoprotein (AFP) screening or, for older mothers, amniocentesis and fetal chromosome analysis (karyotyping). 1.8 Some of the commoner inherited disorders are listed in Table 4 and their Mendelian modes of inheritance are summarised in Fig 2. Almost everyone carries one or more recessively inherited genetic defects and about 3% of couples have a high and recurrent risk of bearing a child with a specific inherited disorder. The fact that about 4,000 such ‘single gene disorders’ are listed in McKusicks’s Mendelian inheritance in man [2] shows on the one hand the collective frequency, and on the other the diversity and individual infrequency of these conditions.