132

brothers, one unborn, the chance of neither showing recombinationwhen the recombination fraction is t is 1-2t when t is small: withthree brothers the more substantial data may cause confusion sinceno opinion can be given if the first two are discrepant. The figureshows the error rate, compensated for errors which cancel out, for 2,3, and 4 meiotic separations (e.g., brother, uncle, cousin).Meanwhile, all that can be done is to ensure that after death, or if

death seems close, DNA is preserved for the benefit of relatives. Anytissue, buffy coat, or even whole blood will be stable if deeply frozen.How deep is unclear, but -20°C is sufficient for a month and- 80°C for years. Prepared DNA is stable at room temperature.Preparation is not difficult and is a reasonable request to a clinicallaboratory on the rare occasions when indicated. The alternative ofestablished cell lines is more expensive and less reliable. 1 g of tissueshould be more than adequate. For whole blood 1 ml has sufficientDNA for about one track, and 20 ml should be adequate, assumingsubstantial amounts are available from potential female carriersseeking advice.

Genetics Laboratory,Department of Biochemistry,University of Oxford,Oxford OX 1 3QU J. H. EDWARDS

HEMISPHERIC ORGANISATION IN 47,XXY BOYS

SiR,-Dr Netley and Dr Rovet (July 31, p. 267) noted an increasein non-righthandedness in their sample of 33 unselected males witha supernumerary X chromosome and suggested that this, incombination with a previously published visual field study, reflectsfailure to establish left hemisphere dominance for language in menwith a supernumerary X chromosome. In our sample of fourteenunselected 47,XXY boys we do not find similar evidence.The fourteen boys (mean age 12 years) were identified by

X-chromatin examination on 40 000 consecutive births over a ten

year period.’ The fourteen chromosomally normal male controlswere matched for age and socioeconomic status. In both groups,thirteen of the boys were righthanded as measured on six hand uses.Thus, there is no increase of non-right-handedness in the 47,XXYboys. Dichotic listening studies were done by an audiologist; thechild had to repeat correctly a message heard in one ear while

ignoring a different message heard in the other ear. The significantright ear advantage of the 47,XXY boys (p<0-05) was consistent

with the pattern in the controls (figure), presumably reflectingcontralateral left hemisphere dominance for language.

3

Mean % correct responses on dichotic listening.

These data on handedness and dichotic listening do not support a

1. Robinson A, Goad WB, Puck TT, Harris J. Studies on chromosomal nondisjunction inman III Am J Hum Genet 1969; 21: 466-85.

2. Willeford JA Assessing central auditory behavior in children. a test battery approach.In: Keith RW, ed. Central auditory dysfunction. New York: Grune & Stratton,1977. 43-72.

3. Kimura D. Cerebral dominance and the perception of verbal stimuli. Can J Psychol1961; 15: 166-71.

conclusion that the functional organisation of the hemispheres in47,XXY boys is different from that of euploid males. Others havequestioned the validity of inferences about hemispheric organisa-tion made on the bases of handedness, visual field studies, ordichotic listening.4 Direct measurement of evoked brain potentialsduring cognitive processing may provide better evidence for therelative involvement of the left and right hemispheres in individualswith sex chromosome anomalies.5 5

National Jewish Hospitaland Research Center,

Denver, Colorado 80206, U.S.A.;and University of ColoradoHealth Sciences Center, Denver

BRUCE G. BENDERMARY H. PUCK

JAMES A. SALBENBLATTARTHUR ROBINSON

PRENATAL DIAGNOSIS OF HARLEQUIN FETUS

SIR,-We have diagnosed a Harlequin fetus at 22 weeks’

gestation. Harlequin syndrome is a fatal, congenital disorder ofkeratinisation whose biochemical basis is unknown.’ The parentswere second cousins and had had four children-two with the

Harlequin syndrome who had died at birth and two normalchildren. During the fifth pregnancy the parents asked us to find outif the fetus was affected. Multiple skin biopsies were done byfetoscopy during the 22nd week of gestation.On binocular loupe examination the skin appeared thickened and

fragile to the touch; light and electron microscopy revealed aremarkably thickened stratum corneum with involvement of bothfollicular and interfollicular epidermis, a feature characteristic of aHarlequin fetus at term. 1

Harlequin fetus.

The pregnancy was terminated in the 24th week of gestation: thefetus had all the characteristic clinical features (figure) withectropion, eclabion, flattened nose, non-patent nares, thickenedskin, and multiple fissures around the mouth and on the neck andforehead. Hands and feet were oedematous.

Dermatology Clinic andCentral Pathological Anatomy Laboratory,

H&ocirc;pital Saint-Louis,75475 Paris, France;Port Royal Gynaecologyand Maternity Clinic;and Pathological Anatomy and

Cytology Service, H&ocirc;pital Cochin, Pans

CLAUDINE BLANCHET-BARDONYVES DUMEZ

FRAN&Ccedil;OIS LABB&Eacute;MARVIN A. LUTZNERANTOINE PUISSANTROGER HENRIONALAIN BERNHEIM

4 Bryden MP. Laterality, funcitonal asymmetry in the intact brain. New York: AcademicPress, 1982

5. Shucard D, Shucard J, Dean K, Pennington B. Electrophysiological and neuropsycho-logical indices of visuo-spatial deficits in Turner syndrome adults. Read at AmericanPsychological Association meeting (August, 1982)

1. Hess JH, Schultz OT. Keratosis diffusus fetalis (ichthyosis congenita) Am J Dis Child1921; 21: 357-88.