Maternal uniparental disomy 7--review and further delineation of the phenotype.
Uniparental disomy (UPD) is defined as the inheritance of both homologous chromosomes from only one parent. So far, maternal UPD 7 has been described in 28 cases. Here, we report 4 new cases, present clinical information of 5 cases previously reported by us, and review the clinical and molecular findings of all 32 cases. We found a phenotype characterized by pre- and postnatal growth retardation, occipitofrontal head circumference in the lower normal range, a triangular face, and retarded bone maturation. Findings of the facial gestalt included a high and broad forehead and a pointed chin. A broad mouth with down-turned corners, prominent ears, café-au-lait spots, hemihypotrophy, or clinodactyly were rarely present. Psychomotor development was delayed in 6 cases. The clinical findings strikingly resemble the phenotype of the heterogeneous Silver-Russell syndrome (SRS). Other anomalies were less frequently found than in SRS. Molecular investigations revealed 11 cases with isodisomy and 17 cases with heterodisomy. In 4 cases this information was not available. From the allelic distribution of the microsatellites investigated, 9 cases might be the consequence of an error at maternal meiosis I, and 6 cases might be due to non-disjunction at maternal meiosis II. Three of the 17 heterodisomic cases had trisomy 7 in chorionic villi, in the remaining cases no prenatal diagnosis through chorionic villus sampling was reported.


CONCLUSIONS
Maternal UPD 7 should investigated in children with pre- and postnatal growth retardation anda facial gestalt characterized by a high and broad forehead and a pointed chin, as well as in cofined placental mosaicism for trisomy 7.
Kotzot
D
D
Institute for Medical Genetics, University of Zurich, Switzerland. Kotzot@medgen.unizh.ch
Balmer
D
D
Baumer
A
A
Chrzanowska
K
K
Hamel
B C
BC
Ilyina
H
H
Krajewska-Walasek
M
M
Lurie
I W
IW
Otten
B J
BJ
Schoenle
E
E
Tariverdian
G
G
Schinzel
A
A
D000015:Abnormalities, Multiple / Q000235:genetics*; D002648:Child; D002869:Chromosome Aberrations; D002897:Chromosomes, Human, Pair 7 / Q000235:genetics*; D002658:Developmental Disabilities / Q000235:genetics; D019066:Facies; D005260:Female; D005317:Fetal Growth Retardation / Q000235:genetics; D006801:Humans; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D010641:Phenotype; D011597:Psychomotor Performance; D013577:Syndrome