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We have investigated the daughter of a woman with Kearns-Sayre syndrome. The woman had a high percentage of deleted mtDNA in muscle, but no deleted mtDNA was detected in fibroblasts, bone marrow, and peripheral blood cells by Southern blot analysis. With PCR, analytical sensitivity was significantly increased, and deleted mtDNA was detected in all examined tissues from this patient. The patient had healthy parents and nine healthy siblings. No deleted mtDNA was detected in blood from the mother of the patient. The patient had an uneventful pregnancy and delivered at term. Deleted mtDNA could not be detected in placenta by Southern blot analysis. With PCR, deleted mtDNA was detected in the majority of placental specimens. This finding may, however, be due to contamination with maternal DNA. The patient's daughter was healthy at age 5 mo, and morphologic examination of muscle was normal. No transmission of deleted mtDNA to the daughter could be detected by Southern blot and PCR analysis of peripheral blood cells, bone marrow, fibroblasts, and muscle. The presence of deleted mtDNA was excluded at a fractional level of less than 1:100,000 in all examined tissues from the daughter.

RFLPs in the phenylalanine hydroxylase (PAH) gene locus were determined in 47 Norwegian nuclear families that had at least one child with phenylketonuria (PKU). The PKU haplotype distribution differed somewhat from that of other European populations. Mutant haplotype 7 is relatively rare in other populations but constituted 20% of all mutant haplotypes in Norway. In 14 of the 17 mutant haplotypes 7, a previously unreported deletion of the BamHI restriction site in exon 7 of the PAH gene was observed. The abrogation of the BamHI site was shown to be due to a G-to-T transversion, changing Gly 272 to Ter 272 in exon 7 of the gene, thus directly identifying the PKU mutation. Unlike the families of the other PKU patients, the families with this mutation clustered along the southeastern coast of Norway, suggesting a founder effect for this mutation.

A presumed monospecific isoantibody to a β -lipoprotein antigen was found by the passive hemagglutination technique in the serum of a young man suffering from hemophilia A, who had r

Analysis of DNA from archival, paraffin-embedded muscle tissue allowed tracing of the mutated dystrophin gene in two families with Duchenne muscular dystrophy. There were no living patients in these families. In one family this diagnosis contributed to the birth of a normal male, in the other family to the demonstration of carrier status. These analyses, based on the polymerase chain reaction, are relatively rapid and simple, and lend increased value to old tissue samples stored in pathology departments.

In typical cases, the diagnosis of fragile X syndrome can be made clinically, but has so far been based on cytogenetic detection of a fragile site on the X chromosome at Xq27.3. Cytogenetic analyses are time-consuming, and false negative results have been a problem. Following the successful molecular cloning of the gene causing the fragile X syndrome, a novel genetic principle was discovered: the "dynamic" DNA mutation. DNA analyses have now the power to distinguish between normal copies of the gene, carrier mutations and fragile X mutations. We have performed both cytogenetic and DNA analyses in an extended fragile X family. DNA fragment length variations in the gene were identified by Southern blot analysis, and the results were used diagnostically in the family. Instability of the mutation (dynamic mutation) occurred between generations and within individuals. DNA analysis, as performed here, improves diagnostic accuracy and genetic counselling in fragile X families.

The diagnosis cystic fibrosis was made in a three years old girl. Her older brother and her mother's sister both had minor symptoms and signs suggestive of this disease. None of 17 mutations in the gene locus for cystic fibrosis was identified in the patient by DNA-analyses. By haplotype analyses her brother, but not her aunt, was shown to share the proband's haplotypes. This family is used as an example of the general diagnostic potential of indirect diagnosis of genetic disease by haplotype analysis. The prerequisite for haplotype analysis is the availability of DNA from both the patient and the patient's relatives, stressing the need for a DNA bank of material from persons with inherited disorders, for future use.

Cold-induced sweating syndrome type 1 (CISS1) is a rare disorder characterized by profuse sweating in a cold environment, determined by mutations in cytokine receptor–like factor 1 ( CRLF1 ).1 Its pathogenesis is not fully understood. It has been demonstrated in vitro that CRLF1 may be involved in inducing differentiation from a noradrenergic to a cholinergic transmitter phenotype. During development, catecholaminergic and cholinergic neurotransmission is required for the induction of secretory function, whereas cholinergic transmission becomes crucial for the maintenance of the secretory responsiveness.2 The abnormal sweat response in CISS1 could be also related to alterations in temperature signals acting on hypothalamus and preoptic areas.1 We report clinical, molecular, skin biopsy, and temperature monitoring data of an Italian boy with CISS1. ### Case report. A 16-year-old boy had come to our observation at 1 year of age. His parents were healthy and unrelated. A brother, with facial dysmorphisms and hypotonia, had died at age 3 months from bronchopulmonary infection. Our patient was hypotonic at birth and experienced severe feeding difficulties. He had elongated face, high-arched palate, weak cry, large pinnae, short hands, tapering fingers, clinodactyly, and reduced tendon reflexes. Concentric needle EMG, nerve conduction velocity (NCV) studies (ulnar, median, peroneal, tibial, and sural nerves), and repetitive nerve stimulation testing excluded a …