Hum. Genet. 38, 7--13 (1977) © by Springer-Verlag 1977
Partial Trisomy 6p due to Familial Translocation t(6;20)(p21;p13) A New Syndrome? Martijn H. Breuning, Jan B. Bijlsma, and Henny F. de France Department of Human Genetics, University of Amsterdam, Sarphatistraat 217, Amsterdam, The Netherlands
Summary. Cytogenetic findings in a case of partial trisomy 6p due to a translocation t(6;20)(p21 ;p13) and eleven balanced translocation heterozygotes are described. The clinical data of the proposita are compared with those of five other published cases. A partial trisomy 6p syndrome is postulated, characterized by: low birth weight, psychomotor retardation, craniofacial abnormalities (such as high prominent forehead, large fontanel, wide sagittal suture, blepharoptosis, low-set and/or malformed ears), congenital heart malformation, small kidneys, and proteinuria. Linkage studies have shown that the breakpoint in chromosome 6 involved in this translocation is close to the HLA gene cluster.
Introduction Since the introduction of banding techniques, several malformation syndromes caused by partial trisomy and/or monosomy have been delineated. Unbalanced structural aberrations involving the short arm of chromosome 6 are uncommon. Therkelsen et al. (1971) described four cases with an unbalanced C / F translocation which subsequently were shown to have been segregants of a familial translocation t(6;20)(p21;p12 or p13) (Therkelsen and Mikkelsen, personal communication, 1977). Chiyo et al. (1975) presented a case of partial trisomy 6p derived from a translocation t(6;15)(p21;p12 or p13). The purpose of this communication is to report another 6p trisomic caused by a reciprocal translocation between chromosomes 6 and 20 segregating in a large Dutch kindred; the clinical features of our case will be compared with those of the above-mentioned cases. Address for offprint requests: Department of Human Genetics, University of Amsterdam,
Sarphatistraat 217, Amsterdam, The Netherlands
8
M . H . Breuning et al.
Case Report The proposita V, 3 (pedigree: Fig. 2) was the third child of healthy unrelated parents; the mother IV, 40 was 24 years old, the father IV, 39 was 26. She had one older sister V, 1, who suffered from mild epileptic attacks but who otherwise developed normally. Between these two children the mother had one prematurely born male child, who died at the age of 6 weeks, one stillbirth after 6 months of gestation, and one spontaneous abortion. The proposita was born after a pregnancy of 38 weeks; this pregnancy was complicated by repeated moderate vaginal blood loss from the second to the sixth month, for which the mother was treated with uterine spasmolytics, gestagens, and vitamins. After the sixth month the mother suffered from severe pruritus for which she received hypnotics and sedatives. During birth there was double enlancement by the umbilical cord. The child started to cry after 10min, following initial breathing difficulties. Her birth weight was 2100 g, length 43 cm, head circumference 30 cm. Two days after birth the child was admitted to hospital because of feeding difficulties. She was discharged after 8 months; frequent readmissions were necessary due to chronic feeding problems and recurrent respiratory and gastrointestinal infections. Both somatic and psychomotor development was retarded. Clinical features at age 2~/2years (Fig. 1): weight 7020g (
Partial Trisomy 6p due to Familial Translocation t(6;20)(p21;p13) A New Syndrome? Martijn H. Breuning, Jan B. Bijlsma, and Henny F. de France Department of Human Genetics, University of Amsterdam, Sarphatistraat 217, Amsterdam, The Netherlands
Summary. Cytogenetic findings in a case of partial trisomy 6p due to a translocation t(6;20)(p21 ;p13) and eleven balanced translocation heterozygotes are described. The clinical data of the proposita are compared with those of five other published cases. A partial trisomy 6p syndrome is postulated, characterized by: low birth weight, psychomotor retardation, craniofacial abnormalities (such as high prominent forehead, large fontanel, wide sagittal suture, blepharoptosis, low-set and/or malformed ears), congenital heart malformation, small kidneys, and proteinuria. Linkage studies have shown that the breakpoint in chromosome 6 involved in this translocation is close to the HLA gene cluster.
Introduction Since the introduction of banding techniques, several malformation syndromes caused by partial trisomy and/or monosomy have been delineated. Unbalanced structural aberrations involving the short arm of chromosome 6 are uncommon. Therkelsen et al. (1971) described four cases with an unbalanced C / F translocation which subsequently were shown to have been segregants of a familial translocation t(6;20)(p21;p12 or p13) (Therkelsen and Mikkelsen, personal communication, 1977). Chiyo et al. (1975) presented a case of partial trisomy 6p derived from a translocation t(6;15)(p21;p12 or p13). The purpose of this communication is to report another 6p trisomic caused by a reciprocal translocation between chromosomes 6 and 20 segregating in a large Dutch kindred; the clinical features of our case will be compared with those of the above-mentioned cases. Address for offprint requests: Department of Human Genetics, University of Amsterdam,
Sarphatistraat 217, Amsterdam, The Netherlands
8
M . H . Breuning et al.
Case Report The proposita V, 3 (pedigree: Fig. 2) was the third child of healthy unrelated parents; the mother IV, 40 was 24 years old, the father IV, 39 was 26. She had one older sister V, 1, who suffered from mild epileptic attacks but who otherwise developed normally. Between these two children the mother had one prematurely born male child, who died at the age of 6 weeks, one stillbirth after 6 months of gestation, and one spontaneous abortion. The proposita was born after a pregnancy of 38 weeks; this pregnancy was complicated by repeated moderate vaginal blood loss from the second to the sixth month, for which the mother was treated with uterine spasmolytics, gestagens, and vitamins. After the sixth month the mother suffered from severe pruritus for which she received hypnotics and sedatives. During birth there was double enlancement by the umbilical cord. The child started to cry after 10min, following initial breathing difficulties. Her birth weight was 2100 g, length 43 cm, head circumference 30 cm. Two days after birth the child was admitted to hospital because of feeding difficulties. She was discharged after 8 months; frequent readmissions were necessary due to chronic feeding problems and recurrent respiratory and gastrointestinal infections. Both somatic and psychomotor development was retarded. Clinical features at age 2~/2years (Fig. 1): weight 7020g (
