### Abstract

The incidence of Down syndrome (DS) families where one of the parents is an heterozygous carrier of pericentric inversion of the heterochromatic region of chromosome 9-inv (9) (qh)-was determined in 3 independent groups of 100 families each. The total number of 17 such families found in the sample is significantly greater than the expected number of 5.73 for a sample of non-DS families of equal size. Consequently, the statistical association of the presence of inv (9) (qh) in one parent with the birth of a DS offspring, and the correlative 3-fold increased risk of a DS child for such families, seem to be demonstrated. A study of the origin of nondisjunction, using restriction fragment length polymorphism (RFLP) segregation analysis with a sufficient number of chromosome 21 specific probes, has provided complete information in 7 of 8 available families. Although the statistical interpretation of the results is not straight-forward, due to the small size of the sample, the observed data do not contradict the assumption that the presence of inv (9) (qh) in a parent increases, by a factor of about 3, the chance that the offspring will inherit an extra chromosome 21 from that parent. Nevertheless, gathering further data appears desirable because stronger evidence would have relevance both for clinical implications and for the understanding of the function of heterochromatin, particularly with respect to meiotic and mitotic processes.

Original language | English (US) |
---|---|

Pages (from-to) | 162-168 |

Number of pages | 7 |

Journal | American Journal of Medical Genetics |

Issue number | SUPPL. 7 |

State | Published - 1990 |

Externally published | Yes |

### Fingerprint

### Keywords

- heterochromatin
- meiosis
- pericentric inversion
- RFLP

### ASJC Scopus subject areas

- Genetics(clinical)
- Medicine(all)

### Cite this

*American Journal of Medical Genetics*, (SUPPL. 7), 162-168.

**Pericentric inversion of chromosome 9 : Prevalence in 300 Down syndrome families and molecular studies of nondisjunction.** / Serra, A.; Brahe, C.; Millington-Ward, A.; Neri, G.; Tedeschi, B.; Tassone, Flora; Bova, R.

Research output: Contribution to journal › Article

*American Journal of Medical Genetics*, no. SUPPL. 7, pp. 162-168.

}

TY - JOUR

T1 - Pericentric inversion of chromosome 9

T2 - Prevalence in 300 Down syndrome families and molecular studies of nondisjunction

AU - Serra, A.

AU - Brahe, C.

AU - Millington-Ward, A.

AU - Neri, G.

AU - Tedeschi, B.

AU - Tassone, Flora

AU - Bova, R.

PY - 1990

Y1 - 1990

N2 - The incidence of Down syndrome (DS) families where one of the parents is an heterozygous carrier of pericentric inversion of the heterochromatic region of chromosome 9-inv (9) (qh)-was determined in 3 independent groups of 100 families each. The total number of 17 such families found in the sample is significantly greater than the expected number of 5.73 for a sample of non-DS families of equal size. Consequently, the statistical association of the presence of inv (9) (qh) in one parent with the birth of a DS offspring, and the correlative 3-fold increased risk of a DS child for such families, seem to be demonstrated. A study of the origin of nondisjunction, using restriction fragment length polymorphism (RFLP) segregation analysis with a sufficient number of chromosome 21 specific probes, has provided complete information in 7 of 8 available families. Although the statistical interpretation of the results is not straight-forward, due to the small size of the sample, the observed data do not contradict the assumption that the presence of inv (9) (qh) in a parent increases, by a factor of about 3, the chance that the offspring will inherit an extra chromosome 21 from that parent. Nevertheless, gathering further data appears desirable because stronger evidence would have relevance both for clinical implications and for the understanding of the function of heterochromatin, particularly with respect to meiotic and mitotic processes.

AB - The incidence of Down syndrome (DS) families where one of the parents is an heterozygous carrier of pericentric inversion of the heterochromatic region of chromosome 9-inv (9) (qh)-was determined in 3 independent groups of 100 families each. The total number of 17 such families found in the sample is significantly greater than the expected number of 5.73 for a sample of non-DS families of equal size. Consequently, the statistical association of the presence of inv (9) (qh) in one parent with the birth of a DS offspring, and the correlative 3-fold increased risk of a DS child for such families, seem to be demonstrated. A study of the origin of nondisjunction, using restriction fragment length polymorphism (RFLP) segregation analysis with a sufficient number of chromosome 21 specific probes, has provided complete information in 7 of 8 available families. Although the statistical interpretation of the results is not straight-forward, due to the small size of the sample, the observed data do not contradict the assumption that the presence of inv (9) (qh) in a parent increases, by a factor of about 3, the chance that the offspring will inherit an extra chromosome 21 from that parent. Nevertheless, gathering further data appears desirable because stronger evidence would have relevance both for clinical implications and for the understanding of the function of heterochromatin, particularly with respect to meiotic and mitotic processes.

KW - heterochromatin

KW - meiosis

KW - pericentric inversion

KW - RFLP

UR - http://www.scopus.com/inward/record.url?scp=0025579568&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0025579568&partnerID=8YFLogxK

M3 - Article

C2 - 1981475

AN - SCOPUS:0025579568

SP - 162

EP - 168

JO - American Journal of Medical Genetics

JF - American Journal of Medical Genetics

SN - 1552-4825

IS - SUPPL. 7

ER -