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  • Journal ofMedical Genetics, 1983, 20, 276-279

    Thoracic-pelvic dysostosis: a 'new' autosomaldominant formAGNES BANKIER AND DAVID M DANKS

    From the Department ofGenetics, Royal Children's Hospital, Parkville, Victoria 3052, Australia.

    SUMMARY A form of thoracic and pelvic dysostosis is reported in a mother and her son. The shortribs caused respiratory distress in the baby and raised the possibility of asphyxiating thoracicdystrophy (ATD). The radiological features, however, distinguish this benign condition from ATDand other described skeletal dysplasias.

    A wide variety ofconditions may result in respiratorydistress in the neonatal period. Respiratory distressmay occur in skeletal disorders as a result of acollapsible larynx (campomelic dysplasia), or acollapsible chest wall (hypophosphatasia and osteo-genesis imperfecta), or because of very short ribs.The short rib syndromes can be divided into threegroups.One group comprises generalised skeletal

    dysplasias with marked shortening of all bonesincluding the ribs. These conditions have beenextensively reviewed.' Respiratory distress is aconstant feature in some of them, for example,thanatophoric dysplasia, achondrogenesis, and theshort rib-polydactyly syndromes. In others it is anoccasional problem in severe cases (for example,achondroplasia, diastrophic dysplasia). These con-ditions can be distinguished on the basis of specificradiological findings of the skull, spine, and limbs.' 2There are isolated reports of short ribs in other

    named generalised skeletal dysplasias, such asmetaphyseal chondrodysplasia,3 and isolated casesnot fitting into any named category, such as the caseof narrow thorax, mesomelic shortening, andhexadactyly.4

    Conditions in the second group show variablelimb reduction and short ribs with a normal skull andspine and include asphyxiating thoracic dysplasia(Jeune) McKusick 20850 (ATD) and chondro-ectodermal dysplasia. These have similar radiologicalfeatures, but can be distinguished clinically.5 6The third group contains cases of isolated thoracic

    dysostosis which do not fit into either of the othercategories.4 7 8We report another short rib syndrome showing

    autosomal dominant inheritance and a goodReceived for publication 28 October 1982.Accepted for publication 10 January 1983.

    prognosis. Thoracic and pelvic dysostosis waspresent in a mother and her son.

    Case report

    This male infant was the second child of unrelatedparents. Delivery was at 39 weeks' gestation byelective lower uterine caesarian section because of asmall pelvic inlet. Apgar scores were 9 at 1 minute and10 at 5 minutes. Birth weight was 2800 g. He had asmall chest and a protuberant abdomen. The liverand spleen were palpable 3 cm and 2 cm below thecostal margins respectively. The limbs appearednormal. There was no evidence of dental, gum, orcardiac anomalies.He developed mild respiratory distress which

    required supplemental oxygen for 12 hours. On day 5,following an episode of aspiration, there was furtherrespiratory distress; the respiratory rate was 70breaths/minute. Chest circumference was 28 cm(3rd centile) compared to the head circumference of36 5 cm (55th centile). The respiratory distressrequired observation in hospital for 6 weeks andtachypnoea persisted until 18 months. Despite thishe thrived and developed normally. His growthfollowed the 3rd centile.At 4 years of age he developed mild episodic

    asthma and still had a narrow pigeon chest deformity.At 5 years of age his chest circumference equalled hishead circumference. When reviewed at 8 years of agehe was of normal intelligence and had no residualrespiratory problems. His vital capacity was 1 .4 1with an FEV1 of 70%, indicating a combination ofmild obstructive airways disease and a reduced lungvolume. His blood pressure was 110/65 and therewas no evidence of renal disease. He was short(10th centile) and he had normal body proportions(upper segment: lower segment = 1 1:1). Chestcircumference was 60 cm and head circumference

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  • Thoracic-pelvic dysostosis: a 'niew' auitosotnal domlinantform 7

    small and shallow sciatic notch and poor develop-ment of the acetabulum. The acetabular rim waspoorly defined, in striking contrast to the acetabularspurs which give the trident appearance seen in ATD.At 7" years of age his chest was normal in size, butstill bell-shaped (fig 2). The upper chest was relativelynarrow and there was a mild pigeon chest deformity.The acetabulum was normal, but the ilium remainedsmall, rounded, and irregular with small sciaticnotches (fig 3). The hands, spine, and skull werenormal.The mother's chest was bell-shaped like her son's,

    with a narrow upper chest (fig 4). Her pelvic x-rayswere more unusual than her son's (fig 5). The iliumwas short and had a tapered neck above the aceta-bulum. Sciatic notches were small resulting in a

    FIGI1Radiographs of the chest on day 5 showing FIG 2 Chest radiograph at 5 years ofage showing thehighi clav'icles and shott iibs. bell-shaped configuration. The chest was nornial in

    size.

    53.9 cm. There were no dysmorphic features. Hewore corrective lenses for hypermetropia with noevidence of retinal dysplasia.

    His mother's height was 151 cm (3rd centile).Her body proportions were normal (upper segment:lower segment =1:1) and she had narrow hips.Her head circumference was 55 cm. She gave nohistory of respiratory problems in childhood andthere was no information about the size of her chestas a child.The neonatal x-ray of the chest confirmed the

    presence of short ribs and high clavicles (fig 1). FIG 3 Radiograph ofthe pelvis at 5yearsofage.There was very little flaring of rib ends and no The appearance is more normal but the ilium small,cupping. The ilium was rounded and small with a rounded, and irregular with shallow sciatic notches.

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    , |~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~_: ..~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~iFIG 4 Radiograph ofthe mother's chest showing abell-shaped configuration.

    FIG 5 Radiograph ofthe mother'spelvis showing thesmall heart-shapedpelvic inlet andshort ilium with anarrow neck above the acetabulum.

    very small heart-shaped pelvic inlet, the featurewhich necessitated delivery by lower uterinecaesarian section. Her hands, spine, and skull wereradiologically normal.

    Discussion

    We believe that this condition is distinct from

    Agnes Bankier and DavidM Danks

    previously described skeletal dysplasias. The abnor-mality was confined to the ribs and pelvis and therewere no cardiac or ectodermal changes. The onlynamed dysplasia requiring serious consideration isATD (Jeune).9ATD is a heterogeneous syndrome.4 9 10-14 There

    are specific radiological changes in the chest andpelvis (similar to those seen in chondroectodermaldysplasia) and in the hands. In one of the reports ofATD the appearance of the pelvis is not described15and in others it is reported as normal.4 7 16 It can beargued that cases without pelvic changes should notbe classified as ATD. Indeed, one of these cases16was subsequently republished as metaphysealchrondrodysplasia.3

    Respiratory failure occurred in the majority ofreported cases of ATD and the degree of respiratorydifficulty has not always been proportional to thedegree of narrowness of the chest, raising thepossibility of pulmonary hypoplasia.12 17 Renalfailure has developed in mid-childhood in a numberof patients who survived the respiratory insufficiencyor never suffered respiratory difficulty." 12 15 18 Therenal changes probably progress during childhood;normal kidney histology has been reported inchildren dying of respiratory complications in theneonatal period.10 12 However, renal involvementhas been described even in the first few days afterbirth.'2 The renal pathology is reminiscent of thatseen in nephronophthisis and includes glomerularand tubular cysts as well as an increase in 'embryonic'connective tissue.12 15 18 Other associated anomalieshave included portal fibrosis with bile duct proli-feration'12 18 and retinal aplasia.19 Two sibs describedas ATD with pancreatic insufficiency16 were sub-sequently reclassified as metaphyseal chondro-dysplasia.3 A few patients have survived into latechildhood or adult life7 1220 and some of thesepatients have shown marked improvement inpulmonary function and radiological appearance ofthe chest and pelvis.2 21 These patients may have acondition which is different from that in the babieswho die early in life.ATD is recessively inherited. There was an

    isolated claim of dominant inheritance in a motherand her child.7 However, the baby in this family had asmall larynx. This is probably a different condition.

    In the baby we have described the degree ofrespiratory distress was less than expected con-sidering the shortness of the ribs. The child made agood recovery and appears to have a lung capacityjust below normal limits at the age of 8. He has noevidence of retinal or renal disease and the radio-logical appearance of his hands is normal. Thechanges in the pelvis were not those ofATD.

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