Short-Rib Thoracic Dysplasia 9 with or without Polydactyly

Alternative Names

  • SRTD9
  • Mainzer-Saldino Syndrome
  • MZSDS
  • Conorenal Syndrome
  • Renal Dysplasia, Retinal Pigmentary Dystrophy, Cerebellar Ataxia, and Skeletal Dysplasia
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WHO-ICD-10 version:2010

Congenital malformations, deformations and chromosomal abnormalities

Other congenital malformations

OMIM Number

266920

Mode of Inheritance

Autosomal recessive

Gene Map Locus

16p13.3

Description

SRTD9 is an extremely rare autosomal recessive skeletal ciliopathy.  It is characterized by phalangeal cone-shaped epiphyses, chronic renal disease, early-onset retinal dystrophy, and developmental delay. Some patients have short stature, craniosynostosis, cerebellar ataxia, and hepatic fibrosis.  Affected children typically present with renal failure.  Retinal dystrophy is varied.  In some patients, vision loss begins in early infancy and progresses rapidly to complete blindness, while in some cases, adults may retain partial vision.

The syndrome follows an autosomal recessive pattern of inheritance.  It is caused by homozygous or compound heterozygous mutations in the IFT140 gene, which encodes one of subunits of the intraflagellar transport (IFT) complex A.  In primary cilia, numerous processes involve IFT such as cilia formation and signaling.  IFT140, thus, plays a very important role in the proper functioning of ciliated cells.  It is also required for the proper assembly of these ciliated cells, especially the cells in the retina.

Epidemiology in the Arab World

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Subject IDCountrySexFamily HistoryParental ConsanguinityHPO TermsVariantZygosityMode of InheritanceReferenceRemarks
266920.1Saudi ArabiaMaleYes Global developmental delay; Abnormality ...NM_014714.4:c.1990G>A, NM_014714.4:c.1525-1G>AHeterozygousAutosomal, RecessiveMaddirevula et al. 2018
266920.2.1Saudi ArabiaMaleYesYes Global developmental delay; Agenesis of ...NM_014714.4:c.1990G>AHomozygousAutosomal, RecessiveMaddirevula et al. 2018
266920.2.2Saudi ArabiaMaleYesYes Global developmental delay; Agenesis of ...NM_014714.4:c.1990G>AHomozygousAutosomal, RecessiveMaddirevula et al. 2018 Relative of 266920.2...
266920.3Saudi ArabiaFemaleYesYes Limb undergrowth; Narrow chest; Polydact...NM_015662.3:c.4630C>THomozygousAutosomal, RecessiveMaddirevula et al. 2018
266920.G.1Saudi ArabiaUnknownYesYes Visual impairmentNM_014714.4:c.1990G>AHomozygousAutosomal, RecessivePatel et al, 2018 3 family members
266920.G.2Saudi ArabiaUnknownYesYes Visual impairment; Renal ciliopathyNM_014714.4:c.1990G>AHomozygousAutosomal, RecessivePatel et al, 2018 5 family members

Other Reports

Saudi Arabia

Bifari et al. (2016) studied eleven probands that presented with infantile nystagmus and poor vision.  Eight subjects had developmental delay.  Four subjects were clinically normal other than their retinal dystrophy.  During infancy, nine were noted to stare at lights and four were noted to have a happy demeanor.  They all had infantile photophilia.  All were hyperopic at the time of cycloplegic refraction, except one older subject, who had keratoconus.  Two of the children had short stubby fingers, and one had renal disease, but four had no evident extraocular disease, including one aged 18-years who also had two older affected siblings in their twenties who remained non-syndromic and were excelling academically.  All patients, except one were found to have the same homozygous mutation in the IFT140 gene.  The exception was found to harbor a different homozygous mutation in the same gene.  

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