Clinical Cytogenetics/Clinical Genetics A45 (0169) 13.1 (0170) 1.89 In situ hybridization shows direct evidence of skewed X inactivation in wo patients with 22q13.3 deletions have similar facies ard monozygotic twin females discordant for Duchenne muscular develcpental patterns. L. Ekie baum3, J. Singa dystrophy. S. M. Zneimer. N. R. Schneider and C. S. Richards . Btlt ,232 I. Tshima2 '3, _Cjinjj, Departments of Medical Jniversity of Texas Southwestern Medical Center at Dallas, and Genetics1 and Paediatrics2, University of Toronto, and GeneScreen, Dallas. Division of Clinical Genetics3. Hospital for Sick Ciildren, A novel combination of conventional and molecular cytogenetic Thronto, Canada techniques was used to examine the discordant expression of an X- inomy distal to 22q13 .3 due to a deletion is rarely linked recessive disorder in a set of monozygotic (MZ) twin females. described. We have recently seen two diildren with similar Both twins carry on their maternal X chromosome an approximately de novo del(22) (ql3.3) whose facial a oearare and 300 kb deletion within the dystrophin gene which is responsible for the neurodevelcpent-al progress are very similar. manifestation of Duchenne muscular dystrophy (DMD) in one MZ Both patients are only mildly dysmorphic. They both have twin (Richards CS et al. AJHG 1990;46:672). A unique 506 bp cDNA long narrow faces with prmninent protruling ears, prnen generated from exon 48 within this gene deletion was hybridized in situ chins, a flattened midface on profile, deep nasal labial to the twins' metaphase chromosomes, a probe which would grooves, a sneswhat praninent nose, frequent tongue presumably hybridize only to the normal X chromosome and not to the thrusting, and an increased carrying angle of their elbow. X chromosome carrying the gene deletion. Chromosomes were Slight terminal hypoplasia of the phalanges is also present identified by reverse-banding and by the addition of BrdUrd in culture in both children. Their height, weight, and head to distinguish early and late replicating X chromosomes that circumference are within normal limits. Both patients had correspond to active and inactive X chromosomes, respectively. This sacral dimples. strategy provided a direct means of determining the relationship Both patients were hypotonic in infancy, had brisk lower patterns and manifestation of an X-linked extremity reflexes, and learned to walk in the second half between X inactivation of the third year of life. Broad based gaits persisted at disease. age 5. Both children have expressive language delay which Hybridization experiments showed predominant inactivation of the is more severe than their global delay. Cognitive and fine normal X chromosome in the twin affected with DMD, which accounts motor skills are moderately delayed in both children. for this twin's manifesting the disease. Unexpectedly, the unaffected Patient A had additional features of a primary persistent twin also showed skewed, predominant inactivation of the X hyperplastic vitreous and Coats disease, as well as chromosome carrying the deletion within the dystrophin gene, superscapilar dimples. accounting for this twin's normal phenotype. Her skewed X Patient B had an umbilical hernia in infancy. inactivation pattern is not the random pattern predicted by the Lyon We conclude that del (22) (q13.3) causes a recognizable hypothesis that is seen in most carriers of X-linked recessive disorders. dysmorphic and developuental syndrome which is distinct from Further, the unaffected twin's X inactivation pattern is not only skewed, and more mild than rost cases of ring (22). but a mirror image of the pattern of her affected twin sister. is study The ring (22) syndrcme is more severe presumably because is the first to show direct evidence at the chromosome level of skewed in and opposite X inactivation of cytogenetically normal X chromosomes, addition to the deletion of 22q, cells with varying resulting in the manifestation of an X-linked recessive disorder in one numbers of rings can be present. of MZ twin females. These results support the suggestion that MZ twinning and skewed X inactivation may be associated events. Clinical Genetics (0171) 1.90 (0172) The relationship between lymphocyte cell surface markers and Syndrome of osteopetrosis associated with cerebro-oculo-facio- serotonin in autistic probands. R.K. Abramson, S. Self, P. skeletal changes: natural history in a patient with prolonged Genco, N. Smith, A. Pendleton, J.Valentine, H.H. Wright, M. survival. Cuccaro, and D.Powell. Univ. of S. Carolina Sch. Med., l.J. Anderson. S.R. Rosengren & R.M. Greenstein. Dept. of Columbia, SC and Med. Univ. of SC, Charleston, SC. Pediatrics, Univ. of Connecticut School of Medicine, Farmington. Familial hyperserotoninemia has been described recently Osteopetrosis is a rare metabolic bone disorder characterized by in about 30-40% of families with an autistic proband. Abnorm- a generalized increase in skeletal density and abnormalities of al immune function, a consistent finding in autistic probands, includes reduced lymphocyte proliferative response to mito- bone modeling. Inherited forms include the autosomal dominant gens, decreased E-rosette forming lymphocytes, and an altered benign type and the autosomal recessive congenita type. In both T /T8ratio. Some probands have absent rubella hemagglutina- forms, osteopetrosis and its complications are the sole tion inhibition antibody responses to rubella vaccine and abnormalities. In 1987, Lerman-Sagie et al. reported a new significantly reduced herpes simplex virus antibodies. syndrome of osteopetrosis associated with cerebro-oculo-facio- In the present study, whole blood serotonins(5HT) were skeletal changes in two male siblings who died by age 4 months. completed on 11 autistic probands. Three probands had 5HT We report a 23 month old girl who was similarly affected during values . 2SD above the mean, 3 had 5HT valuesA 1SD above the infancy but who has exhibited a prolonged clinical course. mean and 5 had normal mean values. Immune function studies She was born at 36 weeks to nonconsanguinous parents after a included B4, T., T4 T8, T11, the T4/T8 ratio, Mo-2, TAC, I3, pregnancy complicated by an elevated MSAFP and decreased and a series og lymphocyte activation markers. The mean fetal movement. Amniocentesis was normal. At birth she was percentage of T cell markers was significantly depressed for noted to have microcephaly, micrognathia, large, low set ears, T [X - 57+10.7, t-3.8, df-55, p-0.0002], T4[X-36t8, t-3.8, bulbous nose, multiple flexion contractures and rocker bottom feet. dr-55, p-0.002], T1, [X-76±7.7, t-3.2, df-55, p-0.001], and I3 Skeletal x-rays showed diffuse osteopetrosis. Laboratory studies [X-16±5, t-2.4, df-55, p-0.0l]. The absolute number of T cell performed at age 4 months showed calcium, phosphorus, markers was normal. and hematocrit within normal limits. At age 5 months, Correlational analysis of T and B cell subsets versus electrolytes 5HT level was completed using Pearson's correlation coefficent. she demonstrated intractable seizures and was diagnosed as Significant negative correlations were observed between 5HT having Lennox-Gastaut syndrome and cortical blindness. and the mean percentage of T3 [r - -0.62, p - 0.039] and T4 Normocytic anemia, hepatosplenomegaly and hypocalcemia [r - -0.61, p - 0.042]. The TAC marker was absent in 20% of became apparent at age 21 months. Renal ultrasound showed probands, had a value of 1 for 60% of probands, and a value of bilateral renal calculi and skeletal x-rays demonstrated marked 2 for 20%. The TAC marker was absent in probands with high osteopenia. Parathyroid hormone levels were normal. 5HT and had a value of 2 in probands with normal 5HT. Our patient is unique in that neither of the previously reported These preliminary data document a relationship between siblings exhibited metabolic abnormalities, anemia, seizure 5HT and abnormal immune function in certain autistic probands. disorder or osteopenia. This patient's course may represent the This might explain the presence of abnormal immune function in natural progression of this disorder in children who survive beyond certain probands and not others. It also emphasizes the infancy. importance of serotonin as a marker in autism. A46 Clinical Genetics (0173) 1.91 (0174) 1.207 A caxpauerized approach to X-linked Prental retardation Toluene Embryopathy Syndrome. G.L. Arnold(l) and Univ. of Colorado Health (XIZ). L. Wilkens-Haug(2). J.F. Arena and H.A. ilubs. University of Miami School of Sciences Center, Denver, CO(1) and Denver General Medicine, The Mailman Center for Child Development, Miami, FL. Hospital, Denver CO(2). Data fron the 34 syrdranes which are currently emerging fian the category of "non-specific XIM'R" were used to develop Inhalation of toluene based solvents in glue and this systen. Clinical and pedigree data, photographs of spray paint continues to be a popular form of norrmal and abnormal family members, literature references, and recreational substance abuse. Toluene vapor summaries fran both the McKusick catalogue and Birth Defects sniffing can induce reversible renal tubular E~nylopedia are entered into a Macintosh II computer system acidosis (RTA). Toluene abuse during pregnancy can through a flatbed scanner, keyboard, or modem. The primary result in significant perinatal morbidity for both advantages of the system include minimal learning time, mother and neonate. A few reports in the excellent quality of pbotographs, easy interaction