Severe psychomotor retardation in a boy with a supernumerary derivative chromosome resulting in partial trisomy 21 and partial trisomy 7p.

We report on a 12-year-old boy with a supernumerary chromosome der(21)t(7; 21)(p21; q21.3)mat, resulting in a partial trisomy 21 and a partial trisomy 7p. The patient has a severe psychomotor retardation.

Linkage analysis identifies the thyroglobulin gene region as a major locus for familial congenital hypothyroidism.

Congenital hypothyroidism affects 1/3000-4000 newborns and it has been estimated that 10-20% are familial cases with an autosomal recessive mode of inheritance. Previous studies of mostly individual cases have led to the identification of mutations in a number of genes, indicating that it is a genetically heterogeneous disease, but no major gene has been identified. In the present investigation, a population-based sample of 23 families with autosomal recessive congenital hypothyroidism, but no signs of goitre, were subject to linkage analysis.

Linkage analysis excludes familial congenital hypothyroidism from chromosome 21.

Congenital hypothyroidism (CH) is a heterogeneous disorder with largely unknown causes, affecting 1/3000-1/4000 new-borns. Individuals with Down syndrome have a much higher incidence of CH than the normal population, probably due to the extra copy of chromosome 21. Moreover, a girl has recently been described with CH and an interstitial deletion of proximal 21q, possibly revealing a recessive disease allele on the undeleted chromosome.

Genetic and linkage analysis of familial congenital hypothyroidism: exclusion of linkage to the TSH receptor gene.

Congenital hypothyroidism affects 1/3000-4000 newborns. The causes of this group of disorders are still largely unknown. Although most cases are sporadic some families have several affected children and/or consanguineous parents, suggesting autosomal recessive inheritance.

Deletion of chromosome 21 in a girl with congenital hypothyroidism and mild mental retardation.

We report on a girl with a large interstitial deletion of the long arm of chromosome 21 and with mild mental retardation, congenital hypothyroidism, and hyperopia. The deletion [del(21)(q11.1-q22.

Molecular analysis of chromosome 21 in a patient with a phenotype of Down syndrome and apparently normal karyotype.

Down syndrome (DS) is caused in most cases by the presence of an extra chromosome 21. It has been shown that the DS phenotype is produced by duplication of only a small part of the long arm of chromosome 21, the 21q22 region, including and distal to locus D21S55. We present molecular investigations on a woman with clinically typical DS but apparently normal chromosomes.

Noonan syndrome with café-au-lait spots and multiple lentigines syndrome are not linked to the neurofibromatosis type 1 locus.

Noonan syndrome, multiple lentigines syndrome (LEOPARD syndrome), Watson syndrome and neurofibromatosis type 1 share certain clinical manifestations. We present a linkage analysis using microsatellite markers located in the neurofibromatosis type 1 region at 17q11 in a family with Noonan syndrome and café-au-lait spots and in another family with multiple lentigines syndrome. No linkage of the disease to the neurofibromatosis type 1 locus was found in the families investigated.