Maj Hulten

Supernumerary chromosomes in six patients

Cytogenetic investigations on five constitutional supernumeraries are presented and correlated to the clinical picture of carriers. Two severely mentally retarded, unrelated patients had similar but not identical inv dup (15) chromosomes and one mildly retarded patient had a small centric fragment, probably a ring chromosome; one infertile man, and a normal father and daughter had double NOR‐stained metacentric markers, interpreted to be entirely heterochromatic.

17. Physical Malformation and Mental Retardation in Association with Structural Autosomal Aberrations

mosomal aberrations be demonstrated. The DNA-content of the sex chromatine was histophotometrically measured in case 2 and 3. No difference from the result found in normal women was demonstrated. Judging from autoradiographic investigations case 2 and 3 had an X-chromosome of normal size. A few cases of the same type have previously been described in the literature. I t seems most likely that in these patients a mosaicism is present where it has not been possible to demonstrate cells with an Y-chromosome, or that during the development of the individual the Y-chromosome has been eliminated. At present a more complicated mechanism for the sexual differentiation can not on the other hand be excluded.

The gene for incontinentia pigmenti: failure of linkage studies using DNA probes to confirm cytogenetic localization

Probes for restriction fragment length polymorphisms mapping between Xp21 and Xq22.3 have been used in a linkage study of incontinentia pigmenti (IP). Six independent sporadic cases of disorders resembling IP with X‐autosome translocations involving the same X chromosome breakpoint (Xp11) have been reported. These observations suggest that the IP gene may be located in the Xp11 chromosomal region. However, the linkage study with DNA probes has failed to confirm this localisation.

Evidence-based information guides to rare chromosome disorders for families and professionals

The purpose of this project is to develop reliable, relevant, accurate leaflets for affected families and health (and other) professionals that fill an information gap about rare chromosome disorders. In 2003 Unique surveyed information materials published in the UK about specific rare chromosome disorders: for over 93% of members, no accessible disorder-specific information was available. Unique asked families what they most wanted to know at diagnosis and what questions remained unanswered. Unique prioritised 66 disorders according to frequency on its database (7,140 member families at February 2010) and absence of existing information accessible to families. Information was compiled from the medical literature, from Unique’s database and from detailed surveys sent to member families. Draft texts were reviewed for accuracy by Unique’s medical adviser and by medical and genetics professional experts in the specific disorders. Photographically illustrated draft leaflets were vetted for content by families. By early 2010, leaflets have been developed on 113 rare chromosome disorders including numerical and structural disorders, subtelomere deletions, mosaic disorders, emerging microdeletion and microduplication syndromes and a broad range of less common diagnoses. Twenty-one leaflets have been translated into at least one European language. Many more leaflets are in preparation or planned. Leaflets are available free to families and the professionals who work with them either in print format or online from Unique’s website at http://www.rarechromo.org. The leaflets improve families’ understanding and acceptance of a rare chromosome disorder and help diminish the acute stress and anxiety associated with diagnosis. They are also proving to be a useful resource for professionals, including health professionals in clinic.