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2001-01-05-10 Answer to the case of the week #41 © Mu?oz Rojas www.TheFetus.net

Answer to case #41

January 05-19, 2001

Submitted by Maria Verônica Mu?oz Rojas, MD, Lu?s Fl?vio Gonçalves, MD, Rodrigo Dias Nunes, MD, Jorge Abi Saab Neto, MD and discussed by Philippe Jeanty

Cl?nica Materno-Fetal, and Maternidade Carmela Dutra, Florian?polis, Brazil

A 18-year-old, G1P0 patient with a HIV positive virus carrier, drug addicted father presented at 37 weeks 3 days.

The following are 2 views of the brain that demonstrated some degree of ventriculomegaly and on the coronal image a large communication between the lateral ventricles, but no separation of the interhemispheric fissure as one would have expected in dysgenesis of the corpus callosum. This is an unusual form of holoprosencephaly: this is semi or lobar holoprosencephaly.

  

The chest demonstrated nicely an pectus excavatum.

The hand demonstrated a simian crease and a clenched fist (actually on one image this is a hard call, but the baby images were provided too).

The baby was very quiet during the examination. This was a sign of alert that the baby was not moving properly, and this is confirmed by the odd position of the limbs and hands. This fetus suffers from arthrogryposis or has is more commonly called akinesia.

An amniocentesis (46, XY) and serum screening for congenital infectious diseases were all normal.

Findings

At the level of the head one can thus observe:

  • lobar/semilobar holoprosencephaly
  • microcephaly

possibly also:

  • micrognathia
  • abnormal nose

Other findings included:

  • pectus excavatum at the level of the chest
  • akinesia/contracture/arthrogryposis

  The difficulties of this case was two-folded:.

  1. First we have all seen so many dysgenesis of the corpus callosum that we think about this diagnosis even when the typical separation of the hemispheres is not present.

  2. Second, this baby had too many findings ! Entering all the keywords in OMIM resulted in no answers. The tactic in those cases is to isolate the least common findings which in this case were:

  • lobar/semilobar holoprosencephaly
  • microcephaly
  • pectus excavatum at the level of the chest
  • akinesia/contracture/arthrogryposis

When all these criteria are used, again no diagnosis is provided by OMIM. So combinations of fewer criteria should be used.

Actually my first impression was the pectus was a significant observation. Although this is a fairly common anomalies, it is rarely reported prenatally and thus to me it appeared significant. However, no combinations with pectus seemed to conform to the findings.

If you are in doubt about which is an important or significant criterion, you can also use OMIM for the information. Simply type the keyword you search and see how many articles there is that include the keyword. Here is a table of those criteria:

Keyword

Number of syndromes

Pectus
Pectus excavatum

90
60

Holoprosencephaly

47

Microcephaly

300

Akinesia

18

This is actually a neat use of OMIM that I had not though before (I know, I know I have been using OMIM for years I should have thought about this before !!!)

With the above table in mind it is clear that the most discriminative keywords will be Holoprosencephaly and Akinesia. Using these 2 criteria provide the following responses:

306990 Holoprosencephaly with fetal akinesia/hypokinesia sequence
300073 Fetal akinesia syndrome, x-linked

Note however that this use of OMIM if far from fool-proof. For instance using Holoprosencephaly and Contracture or Arthrogryposis which would have been valid alternative does not yield any correct diagnosis, and using Holoprosencephaly and Pena-Shokeir only yield the second diagnosis.

This is due to the fact that OMIM is a free text database and that if synonyms are not used in the text (and probably by the authors of the original articles) they are not necessarily included in the text of OMIM. So with this in mind, do your searches with many possible synonyms.

When Veronica and Luis had this baby originally they recognized the diagnosis using the London Dysmorphology Database  (1996), another nice tool, but pricey (and I like how OMIM is thorough).

Checking the first diagnosis shows that this is indeed what the baby has: Holoprosencephaly-fetal akinesia sequence also called Morse syndrome.
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